,transcriber's note3 ,italics text is denoted with underscores1 boldface text with equals signs4 ,other notes are at the end of this e,book4 ,,evolution ,,its ,,nature1 ,,its ,,evidences1 ,,and ,,its ,,relation ,,to ,,religious ,,thought ,,by ,,joseph ,,le ,,conte ,,author ,,of 8,,religion ,,and ,,science10 ,,etc4 ,,and ,,professor ,,of ,,geology ,,and ,,natural ,,history ,,in ,,the ,,university ,,of ,,california ,,second ,,edition1 ,,revised ,,new ,,york3 ,d4 ,,appleton ,,and ,,company1 #gb ,,fifth ,,avenue4 #ahig4 ,,copyright1 #ahhh1 #ahia1 ,,by ,d4 ,,appleton ,,and ,,company4 ,,preface ,,to ,,the ,,second ,,edition4 ,the three years which have elapsed since the publication of the first edition of this work have been years of great activity of thought on many of the subjects treated therein4 ,some changes and additions seemed therefore imperatively called for4 ,for example3 ,there has sprung up recently among the foremost writers on evolution a warm discussion on the factors of evolution1 their number and relative importance4 ,i have therefore added a chapter 7,chap4 ,,iii1 ,part ,,ii7 on this subject--not1 indeed1 to discuss it fully 7for this would be impossible in the limits of a chapter71 but to put the mind of the reader in position to understand it and to judge for himself4 ,again3 ,every reader of the first edition must have remarked that there are many fundamental religious questions which ,i have not touched at all in ,part ,,iii4 ,i had avoided these because my own mind was not yet fully clear4 ,i regarded what ,i then wrote as only a little leaven in a very large lump4 ,i was willing to wait and let it work4 ,in the mean time it has worked in my own mind1 and ,i hope in the minds of others4 ,i have therefore added two chapters to this part4 ,in one ,i simply carry out to their logical consequences the doctrine of the ,divine ,immanency4 ,this brings up the questions of ,first and ,second ,causes2 of ,general and ,special ,providence2 of the ,natural and the ,supernatural2 of ,mind vs4 ,mechanics in ,nature1 etc41 and shows the necessary changes of view which are enforced by the theory of evolution4 ,in the other ,i take up very briefly 8,the ,relation of ,evolution to the ,doctrine of the ,christ40 ,in the discussion of this ,i restrain myself strictly within the limits of the subject as stated above4 ,the only other important changes are in ,chapter ,,iv1 ,part ,,iii1 8,on the ,relation of ,man to ,nature40 ,as ,i regard this as the most important chapter in the whole book1 ,i have endeavored still further to enforce my view of the origin of man's spirit1 and especially to make it clearer by means of several additional illustrations4 ,,joseph ,,le ,,conte4 ,,berkeley1 ,,cal41 ,july #a1 #ahia4 ,,preface ,,to ,,the ,,first ,,edition4 ,the subject of the following work may be expressed in three questions3 ,what is evolution8 ,is it true8 ,what then8 ,surely1 there are no questions of the day more burning than these4 ,much has been written on each of them1 addressed to different classes of minds3 some to the scientific1 some to the popular1 and some to the religious and theological2 but nothing has yet appeared which covers the whole ground and connects the different parts together4 ,much1 very much has been written1 especially on the nature and the evidences of evolution1 but the literature is so voluminous1 much of it so fragmentary1 and most of it so technical1 that even very intelligent persons have still very vague ideas on the subject4 ,i have attempted to give 7#a7 a very concise account of what we mean by evolution1 7#b7 an outline of the evidences of its truth drawn from many different sources1 and 7#c7 its relation to fundamental religious beliefs4 ,i have determined1 above all1 to make a book so small that it may be read through without much expense of time and patience4 ,but the subject is so large that in order to do so it was necessary to sacrifice all but what was most essential1 and to forego all redundancy 7the bane of so-called popular science7 even at the risk of baldness and obscurity4 ,nevertheless1 ,i hope that the first and second parts will be found not only interesting to the intelligent general reader1 but even profitable to the special biologist4 ,i have tried to make these parts as untechnical as possible1 but ,i hope not on that account the less scientific4 ,for ,i am among these who think that it is not necessary to be superficial in order to be popular--that science may be adapted to the intelligent popular mind without ceasing to be science4 ,the third part seems to me still more important just now4 ,there is a deep and widespread belief in the popular mind1 and even to some extent in the scientific mind1 that there is something exceptional in the doctrine of evolution as regards its relation to religious thought and moral conduct4 ,other scientific theories have required only some modifications of religious conceptions1 but this utterly destroys the possibility of all religious belief by demonstrating a pure materialism4 ,now this1 ,i believe1 is a complete misconception4 ,thinking men are fast coming to see this2 some1 indeed1 have mistaken the change for a reaction against evolution4 ,it is a reaction not against evolution1 but only against its materialistic implication4 ,evolution is more and more firmly established every year4 ,the tide of conviction is one which knows no ebb4 ,some clear statement1 in brief space1 of its true relation to religious thought seems1 therefore1 very important at this time4 ,,berkeley1 ,,cal41 ,may1 #ahhg4 ,,contents4 ,,part ,i4 ,,what ,,is ,,evolution8 ,,chapter ,i4 ,,its ,,scope ,,and ,,definition4 ,,page ,a type of evolution--,development of an egg #c ,universality of evolution--,pervades all nature and concerns all departments of thought--,one half of all science-- ,illustrated 7#a7 by human body1 7#b7 by solar system1 7#c7 by society1 7#d7 by earth1 7#e7 by organic kingdom--,the term evolution usually1 but not rightly1 confined to this last #c ,definition of evolution--,i4 ,progressive change--,shown in the animal body1 or the ,ontogenic series--,in the animal scale1 or the ,taxonomic series--,in the geological1 or ,phylogenic series--,the three series similar1 though not identical #h ,,ii4 ,change according to certain laws--,three laws of succession of organic forms #aa 7a7 ,law of differentiation--,early forms are generalized2 afterwards separated into specialized forms--,illustrated by fishes1 by birds--,whole process of differentiation illustrated by growth and branching of a tree #aa 7b7 ,law of progress of the whole--,mistake of confounding evolution with upward progress--,how far true1 and how far false--,illustrated by branching tree--,examples of this mistake in the popular mind--,in the scientific mind #ac 7c7 ,law of cyclical movement--,shown in geological history-- ,age of mollusks1 fishes1 reptiles1 mammals1 man--,illustrated again by a branching tree--,increasing complexity as well as height--,illustrated by diagram #af ,the above three laws are laws of evolution--,differentiation --,shown in the development of an egg1 the type of evolution #ai ,progress of the whole--,not progress of all parts--,shown in the development of an egg #bb ,cyclical movement--,less fundamental than other two--,shown in ,ontogeny of body1 of mind--,increasing complexity--,necessity of continued advance--,otherwise deterioration--,all these laws shown in progress of society---,differentiation shown-- ,progress of the whole but not of all parts shown--,cyclical movement shown--,in social evolution1 however1 there is another element1 viz41 conscious voluntary progress---,this kind of evolution contrasted with the other #bb ,,iii4 ,change by means of resident forces--,this is the point of dispute--,sense in which we use term resident forces--,does not touch question of origin of natural forces #bg ,the two views of the origin of organic forms briefly contrasted --,as to whether natural or supernatural--,as to variability1 definite or indefinite--,as to change from one species to another by transmutation or substitution--,as to universality of law of continuity #bi ,,chapter ,,ii4 ,,the ,,relation ,,of ,,louis ,,agassiz ,,to ,,the ,,theory ,,of ,,evolution4 ,general misunderstanding on this subject--,necessary to give sketch of history of the idea--,greeks1 ,lucretius1 ,swedenborg1 and ,kant--,first scientific presentation by ,lamarck--,general character of ,lamarck's views--,failed1 and rightly so--,next1 ,chambers's 8,vestiges of ,creation0--,its general character-- ,failed1 and rightly so--,some think this unfortunate--,why not so--,an obstacle must be removed and a basis laid #cb ,the obstacle removed--,old views in regard to forces-- ,correlation of forces established--,but vital force considered exception--,therefore living forms also supposed exception to mode of origin of other forms--,then vital forces also correlated--,therefore1 a priori probable that living forms also correlated with other forms as to mode of origin--,thus obstacle removed #ce ,the basis laid--,agassiz laid inductive basis of evolution1 although he refused to build--,he established the laws of evolution and perfected the method of comparison--,importance of method discussed--,the method of notation--,the method of experiment--,the difficulty of applying these to life phenomena--,method of comparison shown--7#a7 ,in ,taxonomic series--7#b7 ,in ,ontogenic series--7#c7 ,in ,phylogenic series --,cuvier the great worker by comparison in the ,taxonomic series--,agassiz in the ,ontogenic and ,phylogenic--,agassiz also established the three laws of evolution given in previous chapter--,thus he laid foundation--,why he did not build-- ,supposed identity of evolution and materialism--,the obstacle being removed and the basis laid1 when evolution again brought forward it was universally accepted1 because the world was prepared--,place of ,agassiz and ,darwin compared--,formal science vs4 physical science--,illustrated by relation of ,kepler to ,newton--,relation of ,agassiz to time cosmos similar to that of ,kepler to space cosmos--,so ,darwin to ,newton-- ,some reflections on the above--,gravitation is the law of space cosmos--,evolution of time cosmos--,of the divine spheral music gravitation is the chordal harmony and evolution the melody #cg ,,part ,,ii4 ,,evidences ,,of ,,the ,,truth ,,of ,,evolution4 ,,chapter ,i4 ,,general ,,evidences ,,of ,,evolution ,,as ,a ,,universal ,,law4 ,evolution is continuity1 causal relation1 gradual becoming --,increasing acceptance of this idea--,first accepted for inorganic forms1 mountains1 continents and seas1 rocks and soils1 earth as a whole1 heavenly bodies--,therefore acknowledged for all inorganics--,influence of geology in bringing about this change--,organic forms3 acknowledged for individuals1 true for classes1 orders1 families1 genera --,races and varieties also formed gradually--,artificial species formed gradually--,examples of gradual changes in wild species--,hyatt's researches--,other examples--,summing up of general evidence--,sufficient ground for induction-- ,but evolution is not only inductively probable but certain1 axiomatic--,it is the law of causation applied to forms1 and therefore a necessary truth #ec ,,chapter ,,ii4 ,,special ,,proofs ,,of ,,evolution4 ,introductory4 ,special proofs necessary--,evolution1 though certain1 is not yet accepted by the popular mind--,different departments from which proofs are drawn #fg ,origin of new organic forms2 the old view briefly stated-- ,necessary to give a brief statement of theories--,old view-- ,permanency of specific types--,supernatural origin of species --,centers of creation--,explanation of facts of geographical distribution--,of geological distribution--,modification of extreme view--,variability1 but within limits--,illustrated #fh ,the new view briefly stated--,indefinite variability of organic forms--,effect of environment on rigid forms--,on plastic forms--,taxonomic groups represent degrees of kinship #gb ,factors of evolution--7#a7 ,physical environment--7#b7 ,use and disuse of organs--7#c7 ,natural selection--7#d7 ,sexual selection--7#e7 ,physiological selection--,its necessity shown --,its operation explained--,compared with natural selection --,cause of variation unknown--,explanation of this is the next great step in the theory of evolution #gc ,,chapter ,,iii4 ,,the ,,grades ,,of ,,the ,,factors ,,of ,,evolution ,,and ,,the ,,order ,,of ,,their ,,appearance4 ,factors of evolution restated2 their grades and the order of their introduction shown--,lamarckian factors1 first in order because they precede sexual reproduction--7#a7 ,environment--7#b7 ,use and disuse--,with sexual reproduction selective factors introduced--7#c7 ,natural selection--7#d7 ,physiological selection--7#e7 ,sexual selection--,with man was introduced 7#f7 the rational factor--,in this process two striking stages--viz41 the introduction of sex and the introduction of reason--,effect of each to hasten the steps of evolution--,the last by far the greater change #ha ,contrast between organic and human evolution--7#a7 ,the meaning of term fittest in each--7#b7 ,destiny of the weak and helpless in each--7#c7 ,the nature of evolutionary transformation in each--7#d7 ,the law of strait and narrow way applied in each--7#e7 ,human evolution is a different kind and on a higher plane #hh ,application to some questions of the day4 ,i4 ,neo-,darwinists1 their position explained--,reasons for dissenting--7a7 ,lamarckian factors preceded all others-- 7b7 ,though now subordinate1 they still underlie and condition all other factors--7c7 ,shown by comparison of phylogeny with ontogeny #ib ,,ii4 ,human progress not identical with organic evolution--,mistake of the materialists--,but neither is it wholly different1 as some suppose #if ,,iii4 ,neo-,darwinism is fatal to hopes of human progress--,reason may use freely ,lamarckian factors1 but can not use natural selection in the same way as ,nature does #ig ,,chapter ,,iv4 ,,special ,,proofs ,,from ,,the ,,general ,,laws ,,of ,,animal ,,structure1 ,,or ,,comparison ,,in ,,the ,,taxonomic ,,series4 ,general ,principles4 ,analogy and homology--,defined and illustrated by examples-- ,wings and limbs--,lungs1 gradual formation of1 traced in the ,taxonomic series--,traced in the ,ontogenic series--,examples of homology in plants3 tuber1 cactus-leaf1 acacia-leaf-- ,definitions repeated and further explained--,common origin is the only explanation of homology #ii ,primary divisions of the animal kingdom--,true ground of such divisions is ability to trace homology--,we take examples only from vertebrata and articulata--,compare to styles of architecture--,to machines--,to branching stem #ajg ,,chapter ,v4 ,,proofs ,,from ,,homologies ,,of ,,the ,,vertebrate ,,skeleton4 ,common general plan--,in several respects--,strongly suggestive of common origin--,details of structure demonstrative of the same #aaa ,special homology of vertebrate limbs #aac ,fore-limbs--,comparison of fore-limbs of mammals1 birds1 reptiles1 and fishes1 part for part--,gradual changes in collar-bone and coracoid--,in position of elbow--,in bones of forearm--,in position of wrist--,in the tread--,the term manus--,number of toes--,modifications for flight in various animals--,for swimming in whales and fishes #aac ,hind-limbs--,comparison of hind-limbs of several mammals-- ,position of knee--,of heel--,plantigrade and digitigrade --,degrees of the latter--,number of toes--,general law in regard to number of similar parts--,order of toe-dropping in artiodactyles--,in perissodactyles #aba ,genesis of the horse--,changes in foot-structure--,same true of other parts of skeleton--,only natural explanation is derivation--,nature compared with man in mode of working-- ,angels--,griffins--,centaurs--,muscular and nervous systems --,visceral organs #abf ,,chapter ,,vi4 ,,homologies ,,of ,,the ,,articulate ,,skeleton4 ,illustrations from this type--,plan of structure entirely different--,general plan of structure explained and modifications shown--,shrimp--,modification of segments and of appendages for various purposes3 swimming1 walking1 eating1 sense--,illustrated by other crustaceans--,by myriapods-- ,by marine worms--,crabs--,embryonic development of crabs-- insects--,modification of segments and appendages--,mouth parts of insects #acb ,illustration of the law of differentiation--,cells--,segments --,individuals--,homologies in other departments of animals1 but these are less familiar--,between primary groups1 homology untraceable in adult forms--,but these also probably connected by common origin--,different views as to origin of vertebrates #add ,,chapter ,,vii4 ,,proofs ,,from ,,embryology1 ,,or ,,comparison ,,in ,,the ,,ontogenic ,,series4 ,resemblance of the three series--,frog1 in ,ontogeny passes through main stages of ,taxonomy and ,phylogeny--,resemblance only general--,many steps dropped out in ,ontogeny #adh 7#a7 ,ontogeny of tailless amphibians--,the frog3 fish stage1 perennibranch stage1 caducibranch stage1 aneural stage--,same stages in ,phylogeny #aej 7#b7 ,aortic arches--,those of lizard described--,origin from gill-arches of fish--,change from one to the other in ,ontogeny of a frog--,same changes in ,phylogeny of lizard--,embryonic condition of mammalian heart and vessels--,gradual change and final condition in birds--,in mammals--,gradual decrease in number of aortic arches as we go up the vertebrate scale-- ,cogency of the argument from aortic arches #aea 7#c7 ,vertebrate brain--,fish brain--,brain of reptiles1 birds1 mammals1 man compared--,human brain passes through similar stages--,changes in complexity of structure in ,taxonomy-- ,same changes in ,ontogeny of mammals--,same in ,phylogeny of reptiles1 birds1 mammals #afb ,cephalization--,explanation of1 in body1 in mind #aga 7#d7 ,fish-tails--,homocercal and heterocercal--,vertebrated and non-vertebrated--,order of change in ,ontogeny--,same in ,phylogeny--,similar changes in birds' tails in ,ontogeny and ,phylogeny--,in other tailless animals--,examples from articulates1 insects1 crustaceans1 etc4 #agb ,illustration of the differentiation of the whole animal kingdom --,development of eggs of all kinds of animals--,this a type of changes in ,phylogeny--,why ,ontogeny repeats ,phylogeny-- ,law of acceleration #agf ,proofs from rudimentary and useless organs--,examples from whale3 ,teeth--,limbs--,hair--,olfactive organs--,examples from man3 muscles1 ccal appendage--,significance of useless organs #agi ,,chapter ,,viii4 ,,proofs ,,from ,,geographical ,,distribution ,,of ,,organisms4 ,geographical faunas and floras--,conditions which limit #ahc ,temperature-regions--,illustrated by plants--,in latitude and in elevation--,same in animal species #ahd ,more perfect definition of regions--,range of different ,taxonomic groups--,gradual shadings on borders of range-- ,shadings out of individuals in number and vigor1 but not in specific character--,as if centers of origin--,effect of east and west barriers--,temperature regions repeated south of the equator1 but not species--,as if centers of origin #ahf ,continental faunas and floras--,temperature zones continuous1 but not species--,reason3 ocean barriers--,as if centers of origin--,polar regions3 one4 ,why--,temperate zone-- ,different species in different continents--,species of ,united ,states and of ,europe almost wholly different--,as if origin local--,exceptions--7#a7 ,introduced species--7#b7 ,hardy or else wide-migrating species--7#c7 ,alpine species--,tropical zone of two continents still more different--,same true of south temperate zone #ahh ,subdivisions of continental faunas and floras--,illustrated by fauna and flora of ,united ,states #aia ,special ,cases--,australia--,madagascar--,galapa gos--,river mussels #aib ,marine species--,same principles applicable--,therefore organic forms grouped in regions1 sub-regions1 provinces1 etc4-- ,primary regions according to ,wallace--,according to ,allen #aib ,theory of the origin of geographical diversity--,specific centers of creation--,objections to4 ,the element of time left out--,progressive change in unlimited time1 or evolution the only rational explanation--,this connects with geographical changes in geological times1 especially the ,glacial epoch-- ,geographical diversity in other times #aic ,most probable view of the general process--,last great period of change was the ,glacial epoch--,this1 therefore1 is the key to geographical distribution--,condition of things during the ,glacial epoch---,in ,america--,changes in temperature--,in physical geography and in species--,in ,europe--,application of principles #aif 7#a7 ,australia--,characteristics of its fauna--,explanation of--,isolation very early--,position of marsupials and monotremes in the ,taxonomic scale--,australia isolated before the ,tertiary--,effect of competition on evolution #bjj 7#b7 ,africa--,african region defined--,two groups of its mammals1 indigenes1 and invaders--,effect of the invasion #bjd 7#c7 ,madagascar--,characteristics of its fauna--,relation to ,african indigenes--,separated before the invasion-- ,significance of its lemurs #bje 7#d7 ,island life--,two kinds of islands--,defined and illustrated by examples--7a7 ,continental islands-- ,general character of fauna--,illustrated by ,madagascar1 ,new ,zealand1 ,british ,islands1 coast-islands of ,california --,characteristics of the faunas of these explained--7b7 ,oceanic ,islands--,defined--,characteristics of faunas and their origin #bjg 7#e7 ,alpine species--,characteristics of and their origin explained--,migrations of ,arctic species during ,glacial times1 and their isolation on mountains #bae ,objection--,mode of change of species on borders of ranges-- ,examples--,sweet-gum--,sequoia #bag ,answer--,distribution of these forms in time1 and their migrations--,they are remnants--,intermediate forms are extinct #bai ,,chapter ,,ix4 ,,proofs ,,from ,,variation ,,of ,,organic ,,forms1 ,,artificial ,,and ,,natural4 ,limitation of the use of experiment in morphology--,unconscious experiments in breeding1 and their results--,principles involved--,inheritance1 immediate and ancestral--,effect of true breeding long continued--,method of selection illustrated by diagram--,formation of a race--,process the same in nature --,show selective effect of physical environment--,of organic environment--,of migrations--,of unlimited time--,other factors of change1 and their effects shown in nature and in domestication--,differences between artificial and natural species #bbb ,first difference1 reversion--,the tendency to reversion described--,the reason explained--,illustrated by the case of the pointer #bbi ,second difference1 intermediate forms--,reason is1 these are eliminated in nature #bcb ,third difference1 cross-fertility--,natural species are usually cross-sterile--,degrees of cross-sterility--,two bases of species1 morphological and physiological--,two kinds of isolation1 sexual repugnance and cross-sterility--,latter most essential--,illustrated by plants and hermaphrodite animals-- ,former only higher animals--,natural laws interfered with by domestication--,illustrated by plants and animals #bcb ,law of cross-breeding--,effect of close breeding--,of crossing varieties to a limit--,the law investigated--,reproduction in lowest organisms--,fission--,gemmation--,intern al gemmation --,sex introduced--,effect of1 is funding of differences in offspring and tendency to variation--,sexual and non-sexual reproduction compared--,separation of sex elements-- ,of sex-individuals--,introduction of sex-attraction-- ,funding of greater differences in offspring--,crossing of varieties--,diagram illustrating effect in vigor--,effect also in plasticity--,application of these principles-- ,necessity of sexual isolation to produce species--,origin of cross-sterility and thus of species by ,dr4 ,romanes's idea-- ,why artificial varieties are cross-fertile--,geographical species sometimes cross-fertile--,application of principles-- ,absence of intermediate links in natural species explained-- ,under what conditions such are found--,further explanation of this point--,illustrated by a growing tree #bcf ,objection answered--,intermediate links ought to be found fossil --,answer 7#a7 ,imperfection of record4 7#b7 ,the term species indefinite4 7#c7 ,transitions between all other taxonomic groups abundant4 7#d7 ,between species1 also1 both living and fossil --,of fossil1 ,planorbis of ,steinheim--,other examples--7#e7 ,why transition-forms are rare--,answer--,changes in every department of nature are paroxysmal--,illustrated--,so the steps of evolution paroxysmal--,critical periods in evolution --,causes of rapid advance--,apparent discontinuity between species--7#a7 changes paroxysmal--7#b7 ,brooks's idea--,male sex is the progressive element--,illustrated by society-- ,effect of prosperous times--,mrs4 ,treat's experiments--,hard times produce excess of males1 and therefore tend to diversity --,summary #bdh ,objection--,egyptian drawings and mummy plants1 show no change --,answer 7#a7 ,time too short4 7#b7 ,we are now in time of slow change4 7#c7 ,all species don't change1 most become extinct4 7#d7 ,evolution is probably slower now than formerly--,reasons for so thinking--,organic evolution approaching completion-- ,other supposed objections #bfe ,origin of beauty--,explanation of1 in higher animals--,in flowering plants--,but in many cases we can't explain #bfi ,incipient organs--,difficulty of explaining--,but these are not objections to the fact of evolution1 but only to the sufficiency of the present theories of evolution4 ,therefore1 all discussion concerns special theories4 ,the fact of evolution is certain #bgj ,,part ,,iii4 ,,the ,,relation ,,of ,,evolution ,,to ,,religious ,,thought4 ,,chapter ,i4 ,,introductory4 ,evolution if true affects every department of thought--,what will be its effect on religious beliefs8--,objection that truth-seeker has nothing to do with effects--,answered #bge ,relation of the true and the good #bgg ,relation of philosophy to life--,the three necessary elements of a rational philosophy--,application to the case in hand-- ,and the subject of ,part ,,iii justified--,exaggerated fears-- ,different forms of the conflict of science and religion--7#a7 ,heliocentric theory--,first effect and final result--7#b7 ,law of gravitation--,effect and result--7#c7 ,antiquity of the earth and cosmos--,effect and result--7#d7 ,antiquity of man --7#e7 ,evolution #bgg ,,chapter ,,ii4 ,,the ,,relation ,,of ,,evolution ,,to ,,materialism4 ,supposed identity--,tendency of the age--,evolution does not differ in this regard from other laws of ,nature--,absurdity of identification illustrated in many ways--7#a7 ,effect of discovery of process of making--7#b7 ,effect of new form of old truth--7#c7 ,manner in which vexed questions are settled and rational philosophy found--,illustrated--,a true philosophy is a reconciliation of partial views--,three possible views of origin of individuals and of species2 two one-sided and partial1 and the third combining1 reconciling1 and therefore rational--,the only bar to speedy reconciliation is dogmatism --,theological and scientific--,the appropriate rebuke for each--,therefore evolution does not differ from other laws in regard to its relation to materialism--,nevertheless1 great changes in our traditional beliefs impending--,main changes are notions concerning ,god1 ,nature1 and man1 in their relations to one another #bhd ,,chapter ,,iii4 ,,the ,,relation ,,of ,,god ,,to ,,nature4 ,the issue in regard to this relation stated--,the growth of the issue described--,the old view of direct relation--,the effect of science and the resulting view--,the compromise-- ,destroyed by evolution--,the issue forced--,the alternative view--,immanence of ,deity--,this view explained--,objection of idealism--,answered--,it is not subjective idealism-- ,objection of pantheism--,answer deferred--,objection that the view is incompatible with practical life--,answered #big ,,chapter ,,iv4 ,,the ,,relation ,,of ,,man ,,to ,,nature4 ,the two extreme views in this regard--,they are views from different points1 psychical and material--,the latter very productive in modern times--,but many fear the final effect-- ,reconciliation is possible--,scientific materialism has two branches--,physiological branch explained--,conclusion-- ,answer--,relation of psychic to brain changes is inscrutable --,the mystery illustrated--,outside and inside view-- ,different from other phenomena in this regard #cjd ,evolution branch--,close relation of man to animals--,therefore must extend immortal spirit to animals--to plants--to all existence1 and thus identify immortality with conservation of force--,embryonic series--,where did spirit enter8-- ,evolution series--,where did spirit enter8--,answer-- ,derived from ,nature--,the true view of origin stated--,show that it is not in discord with other phenomena of evolution --,the five planes of matter and of force--,the change from one to another not gradual now nor in the evolution of natural forces--,consecutive births into higher forms--,every step of these changes taking place now--,relation of these facts to immortality--,the process briefly stated--,omnipresent divine energy individuated to separate entity in man--,anima of animals is spirit in embryo--,came to birth in man-- ,illustrated in other ways--7#a7 ,by more or less completed water-drop--7#b7 ,by submergence and emergence--7#c7 ,by planet birth--7#d7 ,by physical birth--7#e7 ,by grades of organic individuality--7#f7 ,by the body as an instrument of communication between two worlds--,self-consciousness the sign of spirit-individuality--,any animal conscious of self would be immortal--,similar changes in passing from animals to man in all other departments of psychic activity--,objection that other changes of energy not permanent2 answered--,our view of origin compared with alternative views--,plato's view-- ,orthodox view #caa ,some general conclusions--7#a7 ,two series of changes1 brain-changes and mind-changes--,the initiative in animals --,in man--7#b7 ,justification of term 8vital principle0 --,becomes entity in man--7#c7 ,this view is a complete reconciliation of realism and nominalism--7#d7 ,no meaning in ,nature without spirit--,and no meaning in geological history without derivative origin of spirit--,material evolution finds its goal in man1 psychic evolution in the divine man #cbg ,,chapter ,v4 ,,the ,,relation ,,of ,,god ,,to ,,man4 ,question of revelation--,difficulty of the subject--,operation of divine spirit on spirit of man more direct than on ,nature --,this is revelation--,this is no violation of law1 but operation by higher law--,term supernatural is relative-- ,illustrated--,there is but one kind of revelation1 and this to all men in different degrees--,always imperfect1 and therefore must be tried by reason #cca ,,chapter ,,vi4 ,,the ,,objection1 ,,that ,,the ,,above ,,view ,,implies ,,pantheism1 ,,answered4 ,the objection stated and the general answer--,in deepest questions single lines of thought lead to extreme views--,must follow other lines--,these lead to personality #cce 7#a7 ,exact character of relation of ,god and of necessary law to man's freedom is inscrutable #cch 7#b7 ,on the inside of brain-changes we find personality--,so on the inside of natural phenomena must also be person--,in either case science studies the outside only--,in ,nature all is mechanics on the outside1 but all is mind on the inside--,thought behind brain-changes compels belief in same behind natural phenomena--,law of infinite expansion-- ,illustrated by ideas of ,space and ,time--,so also with idea of self--,infinite person inconceivable1 but contrary is more inconceivable--,illustrated by ideas of ,space and ,time #cch 7#c7 ,idea of ,causation and of ,force--,derived from within --,steps of the evolution of this idea--,final result is one infinite personal will--,expansion of idea of causal nexus between phenomena to the idea of one infinite cause #cdb 7#d7 ,idea of design also originates within--,ineradicable1 but changes form--,expands to infinity--,same change produced by science in all our notions concerning ,god--,same in our sense of mystery--,same in our notions concerning creation-- ,same in our conceptions of design--,thus1 self-consciousness behind brain-changes compels belief in ,god behind ,nature--,the closeness of connection in the one case necessitates closeness of connection in the other--,every material change in ,nature caused by a mental change behind ,nature #cde ,,chapter ,,vii4 ,,some ,,logical ,,consequences ,,of ,,the ,,doctrine ,,of ,,the ,,divine ,,immanency4 ,religious thought subject to the law of evolution2 three main stages #cea ,i4 ,conception of ,god--,the three stages shown--7#a7 ,anthropomorphism--7#b7 ,absentee landlordism--7#c7 ,immanence #cea ,,ii4 ,question of ,first and ,second ,causes--,the three stages shown here--7#a7 ,all is ,first ,cause but man-like--7#b7 ,distinction of first and second causes introduced--7#c7 ,identification of these #ced ,,iii4 ,general and ,special ,providence--,the same three stages shown and the same outcome--viz41 identification #cee ,,iv4 ,natural and the supernatural--,the same stages and the same final identification--,question of miracles #cee ,v4 ,question of design or mind in ,nature--,the same three stages and the same solution shown here--,confusion in the minds of modern writers #ceg ,,vi4 ,question of mode of creation--,old and new views contrasted #ceh ,,chapter ,,viii4 ,,relation ,,of ,,evolution ,,to ,,the ,,idea ,,of ,,the ,,christ4 ,comparison of organic with human evolution--,the idea of the first is man1 of the second is the ,christ--,definition of the ,christ as ideal man--,the ,christ ought to differ from us in a superhuman way--,shown by several illustrations--,the ,christ1 as ideal man1 a true object of rational worship--,the ideal of organic evolution comes at the end--,ideal of human evolution must come in the course--,objection that there are many partial ideals answered--,relative vs4 absolute moral ideal4 #cfj ,,chapter ,,ix4 ,,the ,,relation ,,of ,,evolution ,,to ,,the ,,problem ,,of ,,evil4 ,the difficulty of the problem--,the light on it by evolution-- ,evil must be based on the constitution of ,nature and therefore universal--,some of its forms #cfe 7#a7 ,physical evil in animal kingdom--,condition of organic evolution is struggle with an apparently inimical environment --,in its course it seems evil--,looking back from the end it is good4 #cfe 7#b7 ,physical evil in relation to man--,necessary condition of social evolution is also struggle with a seeming evil environment--,but looking back from the end this evil is also seen to be good--,without it man would never have emerged from animality4 #cff 7#c7 ,organic evil--,disease--,this also is the necessary condition of acquisition of knowledge of organic ,nature--,in the course of evolution it seems evil1 but from the end it is seen to be good--,in the physical world1 laws of ,nature are beneficent in their general operation1 and only evil in their specific operation through our ignorance4 #cfg 7#d7 ,moral evil--,moral disease--,difference between this and other forms of evil--,can this also be transmuted into good8--,this is only the highest form of evil1 and therefore subject to the same laws of evolution--,here also elevation comes only through knowledge and power1 and these only through struggle with apparent evil--,in course it seems evil1 looking back from end it is seen to be good to the race-- ,in all1 therefore1 the individual is sacrificed to the race1 but impossible here--,a way of escape found in the nature of a moral being--,in this case not only final victory for the race1 but also within the power of the individual--,in this case success is in proportion to honest effort in right spirit --,roots1 of evil in the necessary law of evolution--,it is the necessary condition of all progress--,without it a moral being is impossible--,from philosophic point of view things are not good and evil1 but only higher and lower--,all things good in their places--,evil is discord--,good is due relation --,action and reaction of higher and lower is the necessary condition of true virtue #cfi ,,part ,i4 ,,what ,,is ,,evolution8 ,,chapter ,i4 ,,its ,,scope ,,and ,,definition4 ,a ,type of ,evolution4--,every one is familiar with the main facts connected with the development of an egg4 ,we all know that it begins as a microscopic germ-cell1 then grows into an egg1 then organizes into a chick1 and finally grows into a cock2 and that the whole process follows some general1 well-recognized law4 ,now1 this process is evolution4 ,it is more--it is the type of all evolution4 ,it is that from which we get our idea of evolution1 and without which there would be no such word4 ,whenever and wherever we find a process of change more or less resembling this1 and following laws similar to those determining the development of an egg1 we call it evolution4 ,universality of ,evolution4--,evolution as a process is not confined to one thing1 the egg1 nor as a doctrine is it confined to one department of science--biology4 ,the process pervades the whole universe1 and the doctrine concerns alike every department of science--yea1 every department of human thought4 ,it is literally one half of all science4 ,therefore1 its truth or falseness1 its acceptance or rejection1 is no trifling matter1 affecting only one small corner of the thought-realm4 ,on the contrary1 it affects profoundly the foundations of philosophy1 and therefore the whole domain of thought4 ,it determines the whole attitude of the mind toward ,nature and ,god4 ,i have said evolution constitutes one half of all science4 ,this may seem to some a startling proposition4 ,i stop to make it good4 ,every system of correlated parts may be studied from two points of view1 which give rise to two departments of science1 one of which--and the greater and more complex--is evolution4 ,the one concerns changes within the system by action and reaction between the parts1 producing equilibrium and stability2 the other concerns the progressive movement of the system1 as a whole1 to higher and higher conditions--the movement of the point of equilibrium itself1 by constant slight disturbance and readjustment of parts on a higher plane1 with more complex inter-relations4 ,the one concerns the laws of sustentation of the system1 the other the laws of evolution4 ,the one concerns things as they are1 the other the process by which they become so4 ,now1 ,nature as a whole is such a system of correlated parts4 ,every department and sub-department of ,nature1 whether it be the solar system or the earth1 or the organic kingdom1 or human society1 or the human body1 is such a system of correlated parts1 and is therefore subject to evolution4 ,we can best make this thought clear by examples3 #a4 ,take1 then1 the human body4 ,this complex and beautiful system of correlated and nicely-adjusted parts may be studied in a state of maturity and equilibrium1 in which all the organs and functions by action and reaction co-operate to produce perfect stability1 health1 and physical happiness4 ,this study is physiology4 ,or else the same may be studied in a state of progressive change4 ,now1 we perceive that the stability is never perfect--the point of equilibrium is ever moving4 ,by the ever-changing number and relative power of the co-operating parts the equilibrium is ever being disturbed1 only to be readjusted on a higher plane1 with still more beautiful and complex inter-relations4 ,this is growth1 development1 evolution4 ,its study is called embryology4 #b4 ,take another example--the solar system4 ,we may study sun1 planets1 and satellites in their mutual actions and reactions1 co-operating to produce perfect equilibrium1 stability1 beautiful order1 and musical harmony4 ,this is the ideal of physical astronomy as embodied in ,laplace's 8,mcanique ,cleste40 ,or we may study the same in its origin and progressive change4 ,now1 we perceive that equilibrium and stability are never absolutely perfect1 but1 on the contrary1 there is continual disturbance with readjustment on a higher plane--continual introduction of infinitesimal discord1 only to enhance the grandeur and complexity of the harmonic relations4 ,this is the nebular hypothesis--the theory of the development of the solar system4 ,it is cosmogony2 it is evolution4 #c4 ,again3 society may be studied in the mutual play of all its social functions so adjusted as to produce social equilibrium1 happiness1 prosperity1 and good government4 ,this is social statics4 ,but equilibrium and stability are never perfect4 ,permanent social equilibrium would be social stagnation and decay4 ,therefore1 we must study society also in its onward movement--the equilibrium ever disturbed1 only to be readjusted on a higher plane with more and more complexly inter-related parts4 ,this is dynamics--social progress4 ,it is evolution4 #d4 ,again3 the earth1 as a whole1 may be studied in its present forms1 and the mutual action of all its parts--lands and seas1 mountains and valleys1 rivers1 gulfs1 and bays1 currents of air and ocean--and the manner in which all these1 by action and reaction1 co-operate to produce climates and physical conditions such as we now find them4 ,this is physical geography4 ,or1 we may study the earth in its gradual progress toward its present condition--the changes which have taken place in all these parts1 and consequent changes in climate2 in a word1 the gradual process of becoming what it now is4 ,this is physical geology--it is evolution4 #e4 ,lastly1 we may study the whole organic kingdom in its entirety as we now find it--the mutual relation of different classes1 orders1 genera1 and species to each other and to external conditions1 and the action and reaction of these in the struggle for life--the geographical distribution of species and their relation to climate and other physical conditions1 the whole constituting a complexly adjusted and permanent equilibrium4 ,this is a science of great importance1 but one not yet distinctly conceived1 much less named4#a ,or1 we may study the same in its gradual progressive approach1 throughout all geological times1 toward the present condition of things1 by continual changes in the parts1 and therefore disturbance of equilibrium and readjustment on a higher plane with more complex inter-relations4 ,this is development of the organic kingdom4 ,in the popular mind it is1 par excellence1 evolution4 ,we might multiply examples without limit4 ,there are the same two points of view on all subjects4 ,as already said1 in the one we are concerned with things as they are2 in the other1 with the process by which they became so4 ,this 8law of becoming0 in all things--this universal law of progressive inter-connected change--may be called the law of continuity4 ,we all recognize the universal relation of things1 gravitative or other1 in space4 ,this asserts the universal causal relation of things in time4 ,this is the universal law of evolution4 ,but it has so happened that in the popular mind the term evolution is mostly confined to the development of the organic kingdom1 or the law of continuity as applied to this department of ,nature4 ,the reason of this is that this department was the last to acknowledge the supremacy of this law2 this is the domain in which the advocates of supernaturalism in the realm of ,nature had made their last stand4 ,but it is wholly unphilosophical thus to limit the term4 ,if there be any evolution1 par excellence1 it is evolution of the individual or embryonic development4 ,this is the clearest1 the most familiar1 and most easily understood1 and therefore the type of evolution4 ,we first take our idea of evolution from this form1 and then extend it to other forms of continuous change following a similar law4 ,but1 since the popular mind limits the term to development of the organic kingdom1 and since1 moreover1 this is now the battleground between the advocates of continuity and discontinuity--of naturalism and supernaturalism in the realm of ,nature--what we shall say will have reference chiefly to this department1 though we shall illustrate freely by reference to other forms of evolution4 ,,definition ,,of ,,evolution4 ,evolution is 7#a7 continuous progressive change1 7#b7 according to certain laws1 7#c7 and by means of resident forces4 ,it may doubtless be defined in other and perhaps better terms1 but this suits our purposes best4 ,embryonic development is the type of evolution4 ,it will be admitted that this definition is completely realized in this process4 ,the change here is certainly continuously progressive2 it is according to certain well-ascertained laws2 it is by forces 7vital forces7 resident in the egg itself4 ,is1 then1 the process of change in the organic kingdom throughout geologic times like this8 ,does it correspond to the definition given above8 ,does ,,it also deserve the name of evolution8 ,we shall see4 ,i4 ,progressive ,change4--,every individual animal body--say man's--has become what it now is by a gradual process4 ,commencing as a microscopic spherule of living but apparently unorganized protoplasm1 it gradually added cell to cell1 tissue to tissue1 organ to organ1 and function to function2 thus becoming more and more complex in the mutual action of its correlated parts1 as it passed successively through the stages of germ1 egg1 embryo1 and infant1 to maturity4 ,this ascending series of genetically connected stages is called the embryonic or ,ontogenic series4#b ,there is another series the terms of which are coexistent1 and which1 therefore1 is not in any sense a genetic or development series1 but which it is important to mention1 because to some degree similar to and illustrative of the last4 ,commencing with the lowest unicelled microscopic organisms1 and passing up to the animal scale1 as it now exists1 we find a series of forms similar1 though not identical1 with the last4 ,here1 again1 we find cell added to cell1 tissue to tissue1 organ to organ1 and function to function1 the animal body becoming more and more complex in structure1 in the mutual action of its correlated parts1 and the mutual action with the environment1 until we reach the highest complexity of structure and of internal and external relations only in the highest animals4 ,this ascending series may be called the natural history series2 or1 the classification or ,taxonomic series4#c ,the terms of this series are1 of course1 not genetically connected2 at least1 not directly so connected4 ,in what way they are connected1 and how the series comes to be similar to the last1 we shall see by-and-by4 ,finally1 there is still a third series1 the grandest and most fundamental of all1 but only recently recognized1 and therefore still imperfectly known4 ,commencing with the earliest organisms1 the very dawn of life1 in the very lowest rocks1 and passing onward and upward through ,eozoic1 ,palozoic1 ,mesozoic1 ,cenozoic1 to the ,psychozoic or present time1 we again find first the lowest forms1 and then successively forms more and more complex in structure1 in the interaction of correlated parts and in interaction with the environment1 until we reach the most complex internal and external relations1 and therefore the highest structure only in the present time4#d ,this series we will call the geological or phylogenic series4#e ,according to the evolution theory1 the terms of this series also are genetically connected4 ,it is1 therefore1 an evolution series4 ,furthermore1 it is the most fundamental of the three series1 because it is the cause of the other two4 ,the ,ontogenic series is like it because it is a brief recapitulation1 through heredity1 as it were from memory1 of its main points4 ,the ,taxonomic series is like it because the rate of advance along different lines was different in every degree1 and therefore every stage of the advance is still represented in a general way among existing forms4 ,some of these points will be explained more fully in future chapters1 in connection with the evidences of the truth of evolution4 ,it will be admitted1 then1 that we find progressive change in organic forms throughout geological times4 ,this is the first point in the definition of evolution4 ,,ii4 ,change according to ,certain ,laws4--,we have shown continuously progressive change in organic forms during the whole geologic history of the earth1 similar in a general way to that observed in embryonic development4 ,we wish now to show that the laws of change are similar in the two cases4 ,what1 then1 are the laws of succession of organic forms in geologic times8 ,i have been accustomed to formulate them thus3 a4 ,the law of differentiation2 b4 ,the law of progress of the whole2 c4 ,the law of cyclical movement4#f ,we will take up these and explain them successively1 and then1 afterward1 show that they are also the laws of embryonic development1 and therefore the laws of evolution4 a4 ,law of ,differentiation4--,it is a most significant fact1 to which attention was first strongly directed by ,louis ,agassiz1 that the earliest representatives of any group1 whether class1 order1 or family1 were not what we would now call typical representatives of that group2 but1 on the contrary1 they were1 in a wonderful degree1 connecting links2 that is1 that along with their distinctive classic1 ordinal1 or family characters they possessed also other characters which connected them closely with other classes1 orders1 or families1 now widely distinct1 without connecting links or intermediate forms4 ,for example3 ,the earliest vertebrates were fishes1 but not typical fishes4 ,on the contrary1 they were fishes so closely connected by many characters with amphibian reptiles1 that we hardly know whether to call some of them reptilian fishes1 or fish-like reptiles4 ,from these1 as from a common vertebrate stem1 were afterward separated1 by slow changes from generation to generation1 in two directions1 the typical fishes and the true reptiles4 ,so1 also1 to take another example1 the first birds were far different from typical birds as we now know them4 ,they were1 on contrary1 birds so reptilian in character1 that there is still some doubt whether bird-characters or reptilian characters predominate in the mixture1 and therefore whether they ought to be called reptilian birds or bird-like reptiles4 ,from this common stem1 the more specialized modern reptiles branched off in one direction and typical birds in another1 and intermediate forms became extinct2 until now1 the two classes stand widely apart1 without apparent genetic connection4 ,this subject will be more fully treated hereafter1 and other examples given4 ,these two will be sufficient now to make the idea clear4 ,such early forms combining the characters of two or more groups1 now widely separated1 were called by ,agassiz connecting types1 combining types1 synthetic types1 and sometimes prophetic types2 by ,dana1 comprehensive types2 and by ,huxley1 generalized types4 ,they are most usually known now as generalized types1 and their widely-separated outcomes specialized types4 ,thus1 in general1 we may say that the widely-separated groups of the present day1 when traced back in geological times1 approach one another more and more until they finally unite to form common stems1 and these in their turn unite to form a common trunk4 ,from such a common trunk1 by successive branching and rebranching1 each branch taking a different direction1 and all growing wider and wider apart 7differentiation71 have been gradually generated all the diversified forms which we see at the present day4 ,the last leafy ramifications--flower-bearing and fruit-bearing--of this tree of life1 are the fauna and flora of the present epoch4 ,the law might be called a law of ramification1 of specialization of the parts1 and diversification of the whole4 b4 ,law of ,progress of the ,whole4--,many imagine that progress is the one law of evolution2 in fact1 that evolution and progress are coextensive and convertible terms4 ,they imagine that in evolution the movement must be upward and onward in all parts2 that degeneration is the opposite of evolution4 ,this is far from the truth4 ,there is1 doubtless1 in evolution1 progress to higher and higher planes2 but not along every line1 nor in every part2 for this would be contrary to the law of differentiation4 ,it is only progress of the whole organic kingdom in its entirety4 ,we can best make this clear by an illustration4 ,a growing tree branches and again branches in all directions1 some branches going upward some sidewise1 and some downward--anywhere1 everywhere1 for light and air2 but the whole tree grows ever taller in its higher branches1 larger in the circumference of its outstretching arms1 and more diversified in structure4 ,even so the tree of life1 by the law of differentiation1 branches and rebranches continually in all directions--some branches going upward to higher planes 7progress71 some pushing horizontally2 neither rising nor sinking1 but only going farther from the generalized origin 7specialization72 some going downward 7degeneration71 anywhere1 everywhere1 for an unoccupied place in the economy of ,nature1 but the whole tree grows ever higher in its highest parts1 grander in its proportions1 and more complexly diversified in its structure4 ,it may be well to pause here a moment to show how this mistaken identification of evolution with progress alone1 without modification by the more fundamental laws of differentiation1 has given rise to misconceptions in the popular and even in the scientific mind4 ,the biologist is continually met with the question1 8,do you mean to say that any one of the invertebrates1 such1 for instance1 as a spider1 may eventually1 in the course of successive generations1 become a vertebrate1 or that a dog or a monkey is on the highway to become a man80 ,by no means4 ,there is but one straight and narrow way to the highest in evolution as in all else1 and few there be that have found it--in fact1 probably two or three only at every step4 ,the animals mentioned above have diverged from that way4 ,in their ancestral history1 they have missed the golden opportunity1 if they ever had it4 ,it is easy to go on in the way they have chosen1 but impossible to get back on the ascending trunk-line4 ,to compare again with the growing tree1 only one straight trunk-line leads upward to the terminal bud4 ,a branch once separated must grow its own way1 if it grow at all4 ,of the same nature is the mistake of some extreme evolutionists1 such as ,dr4 ,bastian and ,professor ,haeckel1 and of nearly all anti-evolutionists1 viz41 that of imagining that the truth of evolution and that of spontaneous generation must stand or fall together4 ,on the contrary1 if life did once arise spontaneously from any lower forces1 physical or chemical1 by natural process1 the conditions necessary for so extraordinary a change could hardly be expected to occur but once in the history of the earth4 ,they are1 therefore1 now1 not only unreproducible1 but unimaginable4 ,such golden opportunities do not recur4 ,evolution goes only onward4 ,therefore1 the impossibility of the derivation of life from non-life now1 is no more an argument against such a derivation once1 than is the hopelessness of a worm ever becoming a vertebrate now1 an argument against the derivative origin of vertebrates4 ,doubtless if life were now extinguished from the face of the earth1 it could not again be rekindled by any natural process known to us2 but the same is probably true of every step of evolution4 ,if any class--for example1 mammals--were now destroyed1 it could not be re-formed from any other class now living4 ,it would be necessary to go back to the time and conditions of the separation of this class from the reptilian stem4 ,therefore1 the falseness of the doctrine of abiogenesis1#g so far from being any argument against evolution1 is exactly what a true conception of evolution and knowledge of its laws would lead us to expect4 c4 ,law of ,cyclical ,movement4--,the movement of evolution has ever been onward and upward1 it is true1 but not at uniform rate in the whole1 and especially in the parts4 ,on the contrary1 it has plainly moved in successive cycles4 ,the tide of evolution rose ever higher and higher1 without ebb1 but it nevertheless came in successive waves1 each higher than the preceding and overborne by the succeeding4 ,these successive cycles are the dynasties or reigns of ,agassiz1 and ages of ,dana2 the reign of mollusks1 the reign of fishes1 of reptiles1 of mammals1 and finally of man4 ,during the early ,palozoic times 7,cambrian and ,silurian7 there were no vertebrates4#h ,but never in the history of the earth were mollusks of greater size1 number1 and variety of form than then4 ,they were truly the rulers of these early seas4 ,in the absence of competition of still higher animals1 they had things all their own way1 and therefore grew into a great monopoly of power4 ,in the later ,palozoic 7,devonian7 fishes were introduced4 ,they increased rapidly in size1 number1 and variety2 and being of higher organization they quickly usurped the empire of the seas1 while the mollusca dwindled in size and importance1 and sought safety in a less conspicuous position4 ,in the ,mesozoic times1 reptiles1 introduced a little earlier1#i finding congenial conditions and an unoccupied place above1 rapidly increased in number1 variety1 and size1 until sea and land seem to have swarmed with them4 ,never before or since have reptiles existed in such numbers1 in such variety of form1 or assumed such huge proportions2 nor have they ever since been so highly organized as then4 ,they quickly became rulers in every realm of ,nature--rulers of the sea1 swimming reptiles2 rulers of the land1 walking reptiles2 and rulers of the air1 flying reptiles4 ,in the unequal contest1 fishes therefore sought safety in subordination4 ,meanwhile mammals were introduced in the ,mesozoic1 but small in size1 low in type 7marsupials71 and by no means able to contest the empire with the great reptiles4 ,but in the ,cenozoic 7,tertiary7 the conditions apparently becoming favorable for their development1 they rapidly increased in number1 size1 variety1 and grade of organization1 and quickly overpowered the great reptiles1 which almost immediately sank into the subordinate position in which we now find them1 and thus found comparative safety4 ,finally1 in the ,quaternary1 appeared man1 contending doubtfully for a while1 with the great mammals1 but soon 7in ,psychozoic7 acquiring mastery through superior intelligence4 ,the huge and dangerous mammals were destroyed and are still being destroyed2 the useful animals and plants were preserved and made subservient to his wants2 and all things on the face of the earth are being readjusted to the requirements of his rule4 ,in all cases it will be observed that the rulers were such because1 by reason of strength1 organization1 and intelligence1 they were fittest to rule4 ,there is always room at the top4 ,to illustrate again by a growing tree3 ,this successive culmination of higher and higher classes may be compared to the flowering and fruiting of successively higher and higher branches4 ,each uppermost branch1 under the genial heat and light of direct sunshine1 received in abundance by reason of position1 grew rapidly1 flowered1 and fruited2 but quickly dwindled when overshadowed by still higher branches1 which1 in their turn1 monopolized for a time the precious sunshine4 ,but observe1 furthermore3 when each ruling class declined in importance1 it did not perish1 but continued in a subordinate position4 ,thus1 the whole organic kingdom became not only higher and higher in its highest forms1 but also more and more complex in its structure and in the interaction of its correlated parts4 ,the whole process and its result is roughly represented in the accompanying diagram1 ,fig4 #a1 in which ,a ,b represents the course of geological time and the curve1 the rise1 culmination1 and decline of successive dominant classes4 ,illustration3 ,,molluscs--,silurian4 ,,fishes--,devon4 and ,carb4 ,,reeptiles--,mesozoic4 ,,mammals--,tert'y and ,quat4 ,,man--,present4 ,,fig4 #a4 ,,the ,,above ,,three ,,laws ,,are ,,laws ,,of ,,evolution4 ,these three laws we have shown are distinctly recognizable in the succession of organic forms in the geological history of the earth4 ,they are1 therefore1 undoubtedly the general laws of succession4 ,are they also laws of evolution8 ,are they also discoverable in embryonic development1 the type of evolution8 ,they are1 as we now proceed to show3 ,differentiation4--,in reproduction the new individual appears3 #a4 ,as a germ-cell--a single microscopic living cell4 #b4 ,then1 by growth and multiplication of cells1 it becomes an egg4 ,this may be characterized as an aggregate of similar cells1 and therefore is not yet differentiated into tissues and organs4 ,in other words1 it is not yet visibly organized2 for organization may be defined as the possession of different parts1 performing different functions1 and all co-operating for one given end1 viz41 the life and well-being of the organism4 #c4 ,then commences the really characteristic process of development1 viz41 differentiation or diversification4 ,the cells are at first all alike in form and function1 for all are globular in form1 and each performs all the functions necessary for life4 ,from this common point now commences development in different directions1 which may be compared to a branching and rebranching1 with more and more complex results1 according as the animal is higher in the scale of organization and advances toward a state of maturity4 ,first1 the cell-aggregate 7egg7 separates into three distinct layers of cells1 called ecto-blast1 endo-blast1 and meso-blast4 ,these by further differentiation form the three fundamental groups of organs and functions1 viz41 the nervous system1 the nutritive system1 and the blood system3 the first presiding over the exchange of force or influence1 by action and reaction with the environment1 and between the different parts of the organism2 the second presiding over the exchange of matter with the environment1 by absorption and elimination2 the third presiding over exchanges of matter between different parts of the organism4 ,the first system of functions and organs may be compared to a system of telegraphy1 foreign and domestic2 the second to foreign commerce2 the third to an internal carrying-trade4 ,following out any one of these groups in higher animals1 say the nervous system1 it quickly differentiates again into two sub-systems1 viz41 cerebro-spinal and ganglionic1 each having its own distinctive functions1 which we can not stop to explain4 ,then the cerebro-spinal again differentiates into voluntary and reflex systems4 ,all of these have meanwhile separated into sensory and motor centers and fibers4 ,then1 taking only the sensory fibers1 these again are differentiated into five special senses1 each having a wholly different function4 ,then1 finally1 taking any one of these1 say the sense of touch or feeling1 this again is differentiated into many kinds of fibers1 each responding to a different impression1 some to heat1 others to cold1 still others to pressure1 etc4 ,we have taken the nervous system2 but the same differentiation and redifferentiation takes place in all other systems1 and is carried to higher and higher points according to the position in the scale of the animal which is to be formed4 ,or1 to vary the mode of presentation a little1 the cells of the original aggregate1 commencing all alike1 immediately begin to take on different forms1 in order to perform different functions4 ,some cells take on a certain form and aggregate themselves to form a peculiar tissue which we call muscle1 and which does nothing else1 can do nothing else1 than contract under stimulus4 ,another group of cells take on another peculiar form and aggregate themselves to form another and very different tissue1 viz41 nervous tissue1 which does nothing and can do nothing but carry influence back and forth between the great external world and the little world of consciousness within4 ,still another group of cells take still another form and aggregate to form still another tissue1 viz41 the epithelial1 whose only function is to absorb nutritive and eliminate waste matters4 ,thus1 by differentiation of form and limitation of function1 or division of labor1 the different parts of the organism are bound more and more closely together by mutual dependence1 and the whole becomes more and more distinctly individuated1 and separation of parts becomes more and more a mutilation1 and finally becomes impossible without death4 ,this process1 as already said1 reaches its highest point only in the later stages of development of the highest animals4 ,progress4--,the law of progress is1 of course1 admitted to be a law of ontogeny2 but observe here1 also1 it is true only of the whole and not necessarily of all the parts1 except from the point of view of the whole4 ,thus1 for example1 starting all from a common form or generalized type1 some cells advance to the dignity of brain-cells1 whose function is somehow connected with the generation or at least the manifestation of thought1 will1 and emotion2 other cells descend to the position of kidney-cells1 whose sole function is the excretion of urine4 ,but here1 also1 the highest cells are successively higher1 and the whole aggregate is successively nobler and more complex4 ,it is again a branching and rebranching1 in every direction1 some going upward1 some downward1 some horizontally1 anywhere1 everywhere1 to increase the complexity of relations internal and external1 and therefore to elevate the plane of the whole4 ,cyclical ,movement4--,lastly1 the law of cyclical movement is also a law of ontogeny and therefore of evolution4 ,this law1 however1 is less fundamental than the other two1 and is1 therefore1 less conspicuous in the ontogenic than in the phylogenic series4 ,it is conspicuous only in the later stages of ontogeny1 and in other higher kinds of evolution1 such as social evolution4 ,for example1 in the ontogenic development of the body and mind from childhood to manhood we have plainly successive culminations and declines of higher and higher functions4 ,in bodily development we have culminating first the nutritive functions1 then the reproductive and muscular1 and last the cerebral4 ,in mental development we have culmination first of the receptive and retentive faculties in childhood1 then of imaginative and sthetic faculties in youth and young manhood2 then of the reflective and elaborative faculties--the faculties of productive work in mature manhood2 and1 finally1 the moral and religious sentiments in old age4 ,the first gathers and stores materials2 the second vivifies and makes them plastic building materials2 the third uses them in actual constructive work--in building the temple of science and philosophy2 and the fourth dedicates that temple only to noblest purposes4 ,observe here1 also1 that when each group of faculties culminates and declines1 it does not perish1 but only becomes subordinate to the next higher dominant group1 and the whole psychical organism becomes not only higher and higher in its highest parts1 but also more and more complex in its structure and in the interaction of its correlated parts4 ,observe1 again1 the necessity laid upon us by this law--the necessity of continued evolution to the end4 ,childhood1 beautiful childhood1 can not remain--it must quickly pass4 ,if1 with the decline of its characteristic faculties1 the next higher group characteristic of youth do not increase and become dominant1 then the glory of life is already past and deterioration begins4 ,have we not all seen sad examples of this8 ,youth1 glorious youth1 must also pass4 ,if the next higher group of reflective and elaborative faculties do not arise and dominate1 then progressive deterioration of character commences here--thenceforward the whole nature becomes coarse1 as we so often see in young men1 or else shrivels and withers1 as we so often see in young women4 ,finally1 manhood1 strong and self-relying manhood1 must also pass4 ,if the moral and religious sentiments have not been slowly growing and gathering strength all along1 and do not now assert their dominance over the whole man1 then commences the final and saddest decline of all1 and old age becomes the pitiable thing we so often see it4 ,but1 if the evolution have been normal throughout2 if the highest moral and religious nature have been gathering strength through all1 and now dominates all1 then the psychic evolution rises to the end--then the course of life is like a wave rising and cresting only at the moment of its dissolution1 or1 like the course of the sun1 if not brightest at least most glorious in its setting4 ,and thus--may we not hope8--the glories of the close of a well-spent life become the pledge and harbinger of an eternal to-morrow8 ,we have thus far illustrated the three laws of succession of organic forms by ontogeny1 because this is the type of evolution2 but they may be illustrated also by other forms of evolution4 ,next to the development of the individual1 undoubtedly the progress of society furnishes the best illustration of these laws4 ,commencing with a condition in which each individual performs all necessary social functions1 but very imperfectly2 in which each individual is his own shoemaker and tailor1 and house-builder and farmer1 and therefore all persons are socially alike2 as society advances1 the constituent members begin to diverge1 some taking on one social function and some another1 until in the highest stages of social organization this diversification or division and subdivision of labor reaches its highest point1 and each member of the aggregate can do perfectly but one thing4 ,thus1 the social organism becomes more and more strongly bound together by mutual dependence1 and separation becomes mutilation4 ,i do not mean to say that this extreme is desirable1 but only that an approach to this is a natural law of social development4 ,is not this the law of differentiation8 ,so also progress is here1 as in other forms of evolution--a progress of the whole1 but not necessarily of every part4 ,some members of the social aggregate advance upward to the dignity of statesmen1 philosophers1 and poets2 some advance downward to the position of scavengers and sewer-cleansers4#aj ,but the highest members are progressively higher1 and the whole aggregate is progressively grander and more complex in structure and functions4 ,so1 again1 the law of cyclical movement is equally conspicuous here4 ,society everywhere advances1 not uniformly1 but by successive waves1 each higher than the last2 each urged by a new and higher social force1 and embodying a new and higher phase of civilization4 ,again3 as each phase declines1 its characteristic social force is not lost1 but becomes incorporated into the next higher phase as a subordinate principle1 and thus the social organism as a whole becomes not only higher and higher1 but also more and more complex in the mutual relations of its interacting social forces4 ,let us not be misunderstood1 however4 ,there is undoubtedly in social evolution something more and higher than we have described1 but which does not concern us here1 except to guard against misconstruction4 ,there is in society a voluntary progress wholly different from the evolution we have been describing4 ,in true or material evolution natural law works for the betterment of the whole utterly regardless of the elevation of the individual1 and the individual contributes to the advance of the whole quite unconsciously while striving only for his own betterment4 ,this unconscious evolution by natural law inherited from the animal kingdom is conspicuous enough in society1 especially in its early stages1 but we would make a great mistake if we imagined1 as some do1 that this is all4 ,besides the unconscious evolution by natural laws1 inherited from below1 there is a higher evolution1 inherited from above1 indissolubly connected with man's spiritual nature--a conscious1 voluntary striving of the best members of the social aggregate for the betterment of the whole--a conscious1 voluntary striving both of the individual and of society toward a recognized ideal4 ,in the one kind of evolution the fittest are those most in harmony with the environment1 and which therefore always survive2 in the other1 the fittest are those most in harmony with the ideal1 and which often do not survive4 ,the laws of this free voluntary progress are little understood4 ,they are of supreme importance1 but do not specially concern us here4 ,we will speak of it again in another chapter4 ,the three laws above mentioned might be illustrated equally well by all other forms of evolution4 ,we have selected only those which are most familiar4 ,they may1 therefore1 be truly called the laws of evolution4 ,we have shown that they are the laws of succession of organic forms4 ,,iii4 ,change by ,means of ,resident ,forces4--,thus far in our argument ,i suppose that most well-informed men will raise no objection4 ,it will be admitted1 ,i think1 even by those most bitterly opposed to the theory of evolution1 that there has been throughout the whole geological history of the earth an onward movement of the organic kingdom to higher and higher levels4 ,it will be admitted1 also1 that there is a grand and most significant resemblance between the course of development of the organic kingdom and the course of embryonic development--between the laws of succession of organic forms and the laws of ontogenic evolution4 ,but there is another essential element in ontogenic evolution4 ,it is that the forces or causes of evolution are natural2 that they reside in the thing developing and in the reacting environment4 ,this we know is true of embryonic development2 is it true also of the geologic succession of organic forms8 ,it is true of ontogeny2 is it true also of phylogeny8 ,if not1 then only by a metaphor can we call the process of change in the organic kingdom throughout geological history an evolution4 ,this is the point of discussion1 and not only of discussion1 but1 alas6 of heated and even angry dispute4 ,the field of discussion is thus narrowed to this third point only4 ,before stating the two opposite views of the cause of evolution1 it is necessary to remind the reader that when the evolutionist speaks of the forces that determine progressive changes in organic forms as resident or inherent1 all that he means1 or ought to mean1 is that they are resident in the same sense as all natural forces are resident2 in the same sense that the vital forces of the embryo are resident in the embryo1 or that the forces of the development of the solar system according to the nebular or any other cosmogonic hypotheses are resident in that system4 ,in other words1 they mean only that they are natural1 not supernatural4 ,this does not1 of course1 touch that deeper1 that deepest of all questions1 viz41 the essential nature and origin of natural forces2 how far they are independent and self-existent1 and how far they are only modes of divine energy4 ,this is a question of philosophy1 not of science4 ,this question is briefly discussed in another place 7,part ,,iii1 ,chap4 ,,iii72 it does not immediately concern us here4 ,the ,two ,views briefly ,contrasted4--,as already stated1 all will admit a grand resemblance between the stages of embryonic development and those of the development of the organic kingdom4 ,this was first brought out clearly by ,louis ,agassiz1 and is1 in fact1 the greatest result of his life-work4 ,all admit1 also1 that the embryonic development is a natural process4 ,is the development of the organic kingdom also a natural process8 ,all biologists of the present day contend that it is2 all the old-school naturalists1 with ,agassiz at their head1 and all anti-evolutionists of every school1 contend that it is not4 ,we take ,agassiz as the type of this school1 because he has most fully elaborated and most distinctly formulated this view4 ,as formulated by him1 it has stood in the minds of many as an alternative and substitute for evolution4 ,according to the evolutionists1 all organic forms1 whether species1 genera1 families1 orders1 classes1 etc41 are variable1 and1 if external conditions favor1 these variations accumulate in one direction and gradually produce new forms1 the intermediate links being usually destroyed or dying out4 ,according to ,agassiz1 the higher groups1 such as genera1 families1 orders1 etc41 are indeed variable by the introduction of new species1 but species are the ultimate elements of classification1 and1 like the ultimate elements of chemistry1 are unchangeable2 and1 therefore1 the speculations of the evolutionist concerning the transmutation of species are as vain as were the speculations of the alchemists concerning the transmutation of metals--that the origin of man1 for example1 from any lower species is as impossible as the origin of gold from any baser metal4 ,both sides admit frequent change of species during geological history1 but one regards the change as a change by gradual transmutation of one species into another through successive generations and by natural process1 the other as change by substitution of one species for another by direct supernatural creative act4 ,both admit the gradual development of the organic kingdom as a whole through stages similar to those of embryonic development2 but the one regards the whole process as natural1 and therefore strictly comparable to embryonic development1 the other as requiring frequent special interference of creative energy1 and therefore comparable rather to the development of a building under the hand and according to the preconceived plan of an architect--a plan1 in this case1 conceived in eternity and carried out consistently through infinite time4 ,it is seen that the essential point of difference is this3 ,the one asserts the variability of species 7if conditions favor1 and time enough is given7 without limit2 the other asserts the permanency of specific forms1 or their variability only within narrow limits4 ,the one asserts the origin of species by 8descent with modifications02 the other1 the origin of species by 8special act of creation40 ,the one asserts the law of continuity 7i4 e41 that each stage is the natural outcome of the immediately preceding stage7 in this1 as in every other department of ,nature2 the other asserts that the law of continuity 7i4 e41 of cause and effect7 does not hold in this department2 that the links of the chain of changes are discontinuous1 the connection between them being intellectual1 not physical4 ,so much for sharp contrasting characterization of the two views1 necessary for clear understanding of much that follows4 ,we will have to give them more fully hereafter when we take up the evidences of evolution in ,part ,,ii4 ,,chapter ,,ii4 ,,the ,,relation ,,of ,,louis ,,agassiz ,,to ,,the ,,theory ,,of ,,evolution4 ,in order to clear up the conception of evolution1 it is necessary to give a brief history of the idea1 and especially to explain the relation of ,louis ,agassiz to that theory4 ,this is the more necessary1 because there is a deep and wide-spread misunderstanding on this subject1 and thus scant justice has been done our great naturalist1 especially by the ,english and ,germans2 and also because this relation is an admirable illustration of an important principle in scientific philosophy4 ,like all great ideas1 we find the first germs of this in ,greek philosophy1 in the cosmic speculations of ,thales and ,pythagoras4 ,next 7about #ajj ,b4 ,c47 we find it more clearly expressed by the ,roman thinker1 ,lucretius1 in his great philosophic poem entitled 8,de ,rerum ,natura40 ,after a dormancy of nearly eighteen centuries it next emerges with still more clearness in the theological speculations of ,swedenborg and the philosophical speculations of ,kant4 ,all these we pass over with bare mention1 because these thinkers approached the subject from the philosophic rather than the scientific side--in the metaphysical rather than the scientific spirit4 ,the first serious attempt at scientific presentation of the subject was by the celebrated naturalist1 ,lamarck1 in a work entitled 8,philosophie ,zologique10 published in #ahji4 ,it is not necessary1 in this rapid sketch1 to give a full account of ,lamarck's views4 ,suffice it to say that the essential idea of evolution1 viz41 the indefinite variability and the derivative origin of species1 was insisted on with great learning and skill1 and illustrated by many examples4 ,with ,lamarck1 the factors of evolution or causes of change of organic forms were--#a4 ,modification of organs in function and therefore in structure1 by a changing environment--external factor2 and1 #b4 ,modification of organs by use and disuse--internal factor4 ,in both cases the modifications are inherited and increased from generation to generation1 without limit4 ,this second factor seems to have taken1 in the mind of ,lamarck1 the somewhat vague and transcendental form of aspiration or upward striving of the animal toward higher conditions4 ,these are acknowledged to-day as true factors of evolution1 but the distinctively ,darwinian factor1 viz41 8divergent variation and natural selection10 was not then thought of4 ,the publication of ,lamarck's views produced a powerful impression1 but only for a little while4 ,pierced by the shafts of ridicule shot by nimble wits of ,paris1 and crushed beneath the heavy weight of the authority of ,cuvier1 the greatest naturalist and comparative anatomist of that or perhaps of any time1 it fell almost still-born4 ,i believe it was best that it should thus perish4 ,its birth was premature2 it was not fit to live4 ,the world was not yet prepared for a true scientific theory4 ,nevertheless1 the work was not without its effect upon some of the most advanced thinkers of that time2 upon ,saint-,hilaire and ,comte in ,france1 and upon ,goethe and ,oken in ,germany4 ,it was good seed sown and destined to spring up and bear fruit in suitable environment2 but not yet4 ,the next attempt worthy of attention in this rapid sketch is that of ,robert ,chambers1 in a little volume entitled 8,vestiges of a ,natural ,history of ,creation10 published in #ahdd4 ,it was essentially a reproduction of ,lamarck's views in a more popular form4 ,it was not a truly scientific work nor written by a scientific man4 ,it was rather an appeal from the too technical court of science to the supposed wider and more unprejudiced court of popular intelligence4 ,it was therefore far more eloquent than accurate2 far more specious than profound4 ,it was1 indeed1 full of false facts and inconsequent reasonings4 ,nevertheless1 it produced a very strong impression on the thinking1 popular mind4 ,but it also quickly fell1 pierced by keen shafts of ridicule1 and crushed beneath the heavy weight of the authority of all the most prominent naturalists of that time1 with ,agassiz at their head4 ,the question for the time seemed closed4 ,i believe1 again1 it was best so1 for the time was not yet fully ripe4 ,i know full well that many think with ,haeckel that biology was kept back half a century by the baneful authority of ,cuvier and ,agassiz2 but ,i can not think so4 ,the hypothesis was contrary to the facts of science as then known and understood4 ,it was conceived in the spirit of baseless speculation1 rather than of cautious induction2 of skillful elaboration rather than of earnest truth-seeking4 ,its general acceptance would have debauched the true spirit of science4 ,i repeat it3 the time was not yet ripe for a scientific theory4 ,the ground must first be cleared and a solid foundation built2 an insuperable obstacle to hearty rational acceptance must first be removed1 and an inductive basis must be laid4 ,the ,obstacle removed4--,the obstacle in the way of the acceptance of the derivative origin of species was the then prevalent notion concerning the nature of life4 ,we must briefly sketch the change which has taken place in the last forty years in our ideas on this subject4 ,until about forty years ago1 the different forces of ,nature1 such as gravity1 electricity1 magnetism1 light1 heat1 chemical affinity1 etc41 were supposed to be entirely distinct4 ,the realm of ,nature was divided up into a number of distinct and independent principalities1 each subject to its own sovereign force and ruled by its own petty laws4 ,about that time it began to be evident1 and is now universally acknowledged1 that all these forces are but different forms of one1 universal1 omnipresent energy1 and are transmutable unto one another back and forth without loss4 ,this is the doctrine of correlation of forces and conservation of energy1 one of the grandest ideas of modern times4 ,but one force seemed still to be an exception4 ,life-force was still believed to be a peculiar1 mysterious principle or entity1 standing above other forces and subordinating them2 not correlated with1 not transmutable unto1 nor derivable from1 other and lower forces1 and therefore in some sense supernatural4 ,now1 if this be true of living forces1 it is perfectly natural1 yea1 almost necessary1 to believe that living forms are wholly different from other forms in their origin4 ,new forms of dead matter may be derived1 but new living forms are underived4 ,other new forms come by natural process1 new organic forms by supernatural process4 ,the conclusion was almost unavoidable4 ,but soon vital force also yielded to the general law of correlation of natural forces4 ,vital forces are also transmutable into and derivable from physical and chemical forces4 ,sun-force1 falling on the green leaves of plants1 is absorbed and converted into vital force1 disappears as light to reappear as life4 ,the amount of life-force generated is measured by the amount of light extinguished4 ,the same is true of animal life4 ,as in the steam-engine the locomotive energy is derived from the fuel consumed and measured by its amount1 so in the animal body1 the animal heat and animal force are derived from and measured by the food and tissue consumed by combustion4 ,thus1 vital force may be regarded as so much force withdrawn from the general fund of chemical and physical forces1 to be again refunded without loss at death4 ,this obstacle is1 therefore1 now removed4 ,if vital force falls in the same category as other natural forces1 there is no reason why living forms should not fall into the same category in this regard as other natural forms4 ,if new forms of dead matter are derived from old forms by modification1 according to physical laws1 there is no reason why new living forms should not also be derived from old forms by modification according to physiological laws4 ,thus1 at last1 the obstacle was removed--the ground was cleared4 ,the ,basis laid4--,but ,science is not content with removal of a priori objections4 ,she must also have positive proofs4 ,the ground must not only be cleared1 but a true inductive basis of facts1 and especially of laws and methods1 must be laid4 ,this was the life-work of ,agassiz4 ,yes1 as strange as it may seem to some1 it is nevertheless true that the whole inductive basis1 upon which was afterward built the modern theory of evolution1 was laid by ,agassiz1 although he himself persistently refused to build upon it any really scientific superstructure4 ,it is plain1 then1 that all attempts at building previous to ,agassiz's work must1 of necessity1 have resulted in an unsubstantial structure--an edifice built on sand1 which could not and ought not to stand4 ,i must stop here in order to explain somewhat fully this important point1 and thus to give due credit to the work of ,agassiz4 ,the title of any scientist to greatness must be determined1 not so much by the multitude of new facts he has discovered as by the new laws he has established1 and especially by the new methods he has inaugurated or perfected4 ,now1 ,i think it can be shown that to ,agassiz1 more than to any other man1 is due the credit of having established the laws of succession of living forms in the geological history of the earth--laws upon which must rest any true theory of evolution4 ,also1 that to him1 more than to any other man1 is due the credit of having perfected the method 7method of comparison7 by the use of which alone biological science has advanced so rapidly in modern times4 ,this is high praise4 ,i wish to justify it4 ,i begin with the method4 ,scientific methods bear the same relation to intellectual progress that tools1 instruments1 machines1 mechanical contrivances of all sorts1 bear to material progress4 ,they are intellectual contrivances--indirect ways of accomplishing results far too hard for bare-handed1 unaided intellectual strength4 ,as the civilized man has little or no advantage over the savage in bare-handed strength of muscle1 and the enormous superiority of the latter in accomplishing material results is due wholly to the use of mechanical contrivances or machines2 even so1 in the higher sphere of intellect1 the scientist makes no pretension to the possession of greater unaided intellectual strength than belongs to the uncultured man1 or even perhaps to the savage4 ,the amazing intellectual results achieved by science are due wholly to the use of intellectual contrivances or scientific methods4 ,as in the lower sphere of material progress the greatest benefactors of the race are the inventors or perfecters of new mechanical contrivances or machines1 so also in the higher sphere of intellectual progress the greatest benefactors of the race are the inventors or perfecters of new intellectual contrivances or methods of research4 ,to illustrate the power of methods1 and the necessity of their use1 take the case of the method of notation1 so characteristic of mathematics1 and take it even in its simplest and most familiar form3 ,nine numeral figures1 having each a value of its own1 and another dependent upon its position2 a few letters1 a and b1 and x and y1 connected by symbols1 and-and 3 that is all4 ,and yet1 by the use of this simple contrivance1 the dullest school-boy accomplishes intellectual results which would defy the utmost efforts of the unaided strength of the greatest genius4 ,and this is only the simplest tool-form of this method4 ,think of the results accomplished by the use of the more complex machinery of the higher mathematics6 ,take next the method of experiment so characteristic of physics and chemistry4 ,the phenomena of the external world are far too complex and far too much affected by disturbing forces and modifying conditions to be understood at once by bare1 unaided intellectual insight4 ,they must first be simplified4 ,the physicist1 therefore1 contrives artificial phenomena under ideal conditions4 ,he removes one complicating condition after another1 one disturbing cause and then another1 watching meanwhile the result1 until finally the necessary condition and the true cause are discovered4 ,on this method rests the whole fabric of the physical and chemical sciences4 ,but when we rise still higher1 viz41 into the plane of life1 the phenomena of ,nature become still more complex and difficult to understand directly2 and yet just here1 where we are the most powerless without some method1 our method of experiment almost wholly fails us4 ,the phenomena of life are not only far more complex than those of dead matter1 but the conditions of life are so nicely adjusted1 the equilibrium of forces so delicately balanced1 that1 when we attempt to introduce our clumsy hands in the way of experiment1 we are in danger of overthrowing the equilibrium1 of destroying the conditions of the experiment1 viz41 life2 and then the whole problem falls immediately into the domain of chemistry4 ,what shall we do8 ,in this dilemma we find that ,nature herself has already prepared for us1 ready to hand1 an elaborate series of simplified conditions equivalent to experiments4 ,the phenomena of life are1 indeed1 far too complex to be at once understood--the problem of life too hard to be solved--in the higher animals2 but1 as we go down the animal scale1 complicating conditions are removed one by one1 the phenomena of life become simpler and simpler1 until in the lowest microscopic cell or spherule of living protoplasm we finally reach the simplest possible expression of life4 ,the equation of life is reduced to its simplest terms1 and now1 if ever1 we begin to understand the true value of the unknown quantity4 ,this is the natural history series1 or ,taxonomic series1 already spoken of on page #aj4 ,again1 ,nature has prepared1 and is now preparing daily before our eyes1 another series of gradually simplified conditions4 ,commencing with the mature condition of one of the higher animals--for example1 man--and going backward along the line of individual history through the stages of infant embryo1 egg and germ1 we find again the phenomena of life becoming simpler and simpler1 until we again reach the simplest conceivable condition in the single microscopic cell or spherule of living protoplasm4 ,this1 as already explained1 is the embryonic or ,ontogenic series4 ,again1 that there be no excuse for man's ignorance of the laws of life1 ,nature has prepared still another series2 and this the grandest of all1 for it is the cause of both the others4 ,commencing with the plants and animals of the present epoch1 and going back along the track of geological times1 through ,cenozoic1 ,mesozoic1 ,palozoic1 ,eozoic1 to the very dawn of life--the first syllable of recorded time--and we find again a series of organic forms growing simpler and simpler1 until1 if we could find the very first1 we would undoubtedly again reach the simplest condition in the lowest conceivable forms of life4 ,this1 as we have already seen1 is the geologic or evolution1 or ,phylogenic series4 ,we have already explained these three series1 only in this connection it suits our purpose to take the terms backward4 ,now1 it is by comparison of the terms of each of these series going up and down1 and watching the first appearance1 the growth1 and the perfecting of tissues1 organs1 functions1 and by the comparison of the three series with one another term by term--,i say it is wholly by comparison of this kind that biology has in recent times become a true inductive science4 ,this is the 8method of comparison40 ,it is the great method of research in all those departments which can not be readily managed by the method of experiment4 ,it has already regenerated biology1 and is now applied with like success in sociology under the name of historic method4 ,yes2 anatomy became scientific only through comparative anatomy1 physiology through comparative physiology1 and embryology through comparative embryology4 ,may we not add1 sociology will become truly scientific only through comparative sociology1 and psychology through comparative psychology8 ,now1 while it is true that this method1 like all other methods1 has been used1 from the earliest dawn of thought1 in a loose and imperfect way1 yet it is only in very recent times that it has been organized1 systematized1 perfected1 as a true scientific method1 as a great instrument of research2 and the prodigious recent advance of biology is due wholly to this cause4 ,now1 among the great leaders of this modern movement1 ,agassiz undoubtedly stands in the very first rank4 ,i must try to make this point plain1 for it is by no means generally understood4 ,cuvier is acknowledged to be the great founder of comparative anatomy4 ,he it was that first perfected the method of comparison1 but comparison only in one series--the ,taxonomic4 ,von ,baer and ,agassiz added to this comparison in the ontogenic series also1 and comparison of these two series with each other1 and therefore the application of embryology to the classification of animals4 ,if ,von ,baer was the first announcer1 ,agassiz was the first great practical worker by this method4 ,last and most important of all1 in its relation to evolution1 ,agassiz added comparison in the geologic or phylogenic series4 ,the one grand idea underlying ,agassiz's whole life-work was the essential identity of the three series1 and therefore the light which they must shed on one another4 ,the two guiding and animating principles of his scientific work were--#a4 ,that the embryonic development of one of the higher representatives of any group repeated in a general way the terms of the ,taxonomic series in the same group1 and therefore that embryology furnished the key to a true classification2 and1 #b4 ,that the succession of forms and structure in geological times in any group is similar to the succession of forms and structure in the development of the individual in the same group1 and thus that embryology furnishes also the key to geological succession4 ,in other words1 during his whole life1 ,agassiz insisted that the laws of embryonic development 7ontogeny7 are also the laws of geological succession 7phylogeny74 ,surely this is the foundation1 the only solid foundation1 of a true theory of evolution4 ,it is true that ,agassiz1 holding as he did the doctrine of permanency of specific types1 and therefore rejecting the doctrine of the derivative origin of species1 did not admit the causal or natural relation of phylogenic succession to embryonic succession and taxonomic order as we now believe it--it is true that for him the relation between the three series was an intellectual not a physical one--consisted in the preordained plans of the ,creator1 and not in any genetic connection or inherited property2 but evidently the first and greatest step was the discovery of the relation itself1 however accounted for4 ,the rest was sure to follow4 ,but more4 ,not only did ,agassiz establish the essential identity of the geologic and embryonic succession1 the general similarity of the two series1 phylogenic and ontogenic1 but he also announced and enforced all the formal laws of geologic succession 7i4 e41 of evolution71 as we now know them4 ,these1 as already stated and illustrated1 are the law of differentiation1 the law of progress of the whole1 and the law of cyclical movement1 although he did not formulate them in these words4 ,no true inductive evidence of evolution was possible without the knowledge of these laws1 and for this knowledge we are mainly indebted to ,agassiz4 ,he well knew also that they were the laws of embryonic development and therefore of evolution2 but he avoided the word evolution1 as implying the derivative origin of species1 and used instead the word development1 though it is hard to see in what the words differ4 ,thus1 it is evident that ,agassiz laid the whole foundation of evolution1 solid and broad1 but refused to build any scientific structure on it2 he refused to recognize the legitimate1 the scientifically necessary outcome of his own work4 ,nevertheless1 without his work a scientific theory of evolution would have been impossible4 ,without ,agassiz 7or his equivalent71 there would have been no ,darwin4 ,there is something to us supremely grand in this refusal of ,agassiz to accept the theory of evolution4 ,the opportunity to become the leader of modern thought1 the foremost man of the century1 was in his hands1 and he refused1 because his religious1 or1 perhaps better1 his philosophic intuitions1 forbade4 ,to ,agassiz1 and1 indeed1 to all men of that time1 to many1 alas6 even now1 evolution is materialism4 ,but materialism is ,atheism4 ,will some one say1 the genuine ,truth-seeker follows where she seems to lead whatever be the consequences8 ,yes2 whatever be the consequences to one's self1 to one's opinions1 prejudices1 theories1 philosophies1 but not to still more certain truth4 ,now1 to ,agassiz1 as to all genuine thinkers1 the existence of ,god1 like our own existence1 is more certain than any scientific theory1 than anything can possibly be made by proof4 ,from his standpoint1 therefore1 he was right in rejecting evolution as conflicting with still more certain truth4 ,the mistake which he made was in imagining that there was any such conflict at all4 ,but this was the universal mistake of the age4 ,a lesser man would have seen less clearly the higher truth and accepted the lower4 ,a greater man would have risen above the age1 and seen that there was no conflict1 and so accepted both4 ,all thinking men are coming to this conclusion now1 but none had done so then4 ,now1 then1 at last1 the obstacle of supernaturalism in the realm of ,nature having been removed by the establishment of the doctrine of correlation of natural forces1 and the extension of this doctrine to embrace also life-force2 and now also a broad and firm basis of carefully-observed facts and well-established laws of succession of organic forms having been laid by ,agassiz1 when again1 for the third time1 the doctrine of origin of species 8by derivation with modifications0 was brought forward by ,darwin in a far more perfect form1 with more abundant illustrative materials1 and with a new and most potent factor of modification--viz41 divergent variations and natural selection--it found the scientific world already fully prepared1 and anxiously waiting4 ,i say anxiously waiting--for the supposed supernatural origin of species had been the one exception to the otherwise universal law of cause and effect1 or the law of continuity4 ,it was therefore in open contradiction to the whole drift of scientific thought for five hundred years4 ,is it any wonder1 then1 that the derivative origin of species was welcomed with joy by the scientific world8 ,for five hundred years1 scientific thought1 like a rising tide which knows no ebb1 had tended thitherward with ever-increasing pressure1 but kept back by the one supposed fact of the supernatural origin of species4 ,darwin lifted the gate1 and the in-rushing tide flooded the whole domain of thought4 ,what1 then1 is the place of ,agassiz in biological science8 ,what is the relation of ,agassiz to ,darwin--of ,agassizian development to ,darwinian evolution8 ,i answer1 it is the relation of formal science to physical or causal science4 ,agassiz advanced biology to the formal stage2 ,darwin carried it forward1 to some extent at least1 to the physical stage4 ,all true inductive sciences in their complete development pass through these two stages4 ,science in the one stage treats of the laws of phenomena2 in the other1 of the causes or explanation of these laws4 ,the former must precede the latter1 and form its foundation2 the latter must follow the former1 and constitute its completion4 ,the change from the one to the other is always attended with prodigious impulse to science4 ,to illustrate3 ,until ,kepler1 astronomy was little more than an accumulation of disconnected facts concerning celestial motions--abundant materials1 but no science2 piles of brick and stone1 but no building4 ,kepler reduced this chaos to beautiful order and musical harmony by the discovery of the three great laws which bear his name1 and therefore he has been justly called the legislator of the heavens--the lawgiver of space4 ,but1 had he been asked the cause of these beautiful laws1 he could only have answered1 8,the first cause--the direct will of the ,deity40 ,a good answer and a true1 but not scientific2 because it places the question beyond the domain of science1 which deals only with second or physical causes4 ,but ,newton comes forward and gives a physical cause4 ,he shows that all these beautiful laws are the necessary result of gravitation2 and thus astronomy becomes a physical science4 ,so1 until ,agassiz1 the facts of geological succession of organic forms were in a state of lawless confusion4 ,agassiz by establishing the three great laws of succession1 which ought to bear his name1 reduced this chaos to order and beauty2 and1 therefore1 he might justly be called the legislator of geological history--the lawgiver of time4 ,but1 when asked the cause of these laws1 he could only answer1 and did indeed answer1 8,the plans of the ,creator40 ,a noble answer and true1 but not scientific4 ,darwin now comes forward and gives1 partly at least1 the cause of these laws4 ,he shows that all these beautiful laws are explained by the doctrine of 8origin of species by derivation with modifications02 that these laws are not ultimate1 but derivative from more fundamental laws of life2 and thus biology is advanced one step1 at least1 toward the causal stage4 ,newton and ,darwin substituted second causes for first cause--natural for supernatural4 ,they each in his own department broke the bonds of supernaturalism in the domain of ,nature4 ,one more important reflection3 ,there are two1 and only two1 fundamental conditions of material existence--space and time4 ,there are1 therefore1 two1 and only two1 cosmoses--space-cosmos and time-cosmos4 ,these have been redeemed from confusion and reduced to law and order and beauty--changed from chaos to cosmos--by science4 ,for this result we are chiefly indebted1 in the one case1 to ,kepler and ,newton2 in the other1 to ,agassiz and ,darwin4 ,the universal law1 in the one cosmos1 is the law of gravitation2 in the other1 the law of evolution4 ,traced by analysis to its deepest roots of philosophic truth1 the one law may be called the divine mode of sustentation2 the other1 the divine process of creation4 ,or again3 we have all heard of the 8music of the spheres0--a beautiful and significant name used by the old thinkers for the divine order of the universe--a music heard not by human ear1 but only by the attentive human spirit4 ,harmonic relation apprehended by reason we call ,law1 and its embodiment ,science2 the same apprehended by the imagination and sthetic sense1 we call ,beauty1 and its embodiment ,art1 music4 ,now1 in music there are two kinds of harmony1 simultaneous and consecutive--chordal harmony and melody4 ,these must be combined to produce the grandest effect4 ,so in cosmic order1 too1 there are two kinds of harmonic relation--the co-existent in space and the consecutive in time4 ,the law of gravitation expresses the universal harmonic inter-relation of objects co-existent in space1 the law of evolution1 the universal harmonic relation of forms successive in time4 ,of the divine spheral music1 the one is the chordal harmony1 the other the consecutive harmony or melody4 ,combined they form the divine chorus which 8the morning stars sang together40 ,,part ,,ii4 ,,evidences ,,of ,,the ,,truth ,,of ,,evolution4 ,,chapter ,i4 ,,general ,,evidences ,,of ,,evolution ,,as ,a ,,universal ,,law4 ,let us again remind the reader that evolution means1 first of all1 continuity4 ,the law of evolution1 although it doubtless means much more1 means1 first of all1 a law of continuity1 or causal relation throughout ,nature4 ,it means that1 alike in every department of ,nature1 each state or condition grew naturally out of the immediately preceding4 ,in a word1 it means that1 in the course of ,nature1 nothing appears suddenly and without natural cause1 but1 on the contrary1 everything is the natural and usually the gradual outcome of a previous condition4 ,this is now admitted by every one in regard to nearly everything3 evolutionists apply it to the whole course of ,nature4 ,i said this is now admitted by every one in regard to nearly everything2 but this has not always been so4 ,the world has come to its present position on this subject only by a very gradual process4 ,let us then trace rapidly the history of the gradual change1 for it will prepare us for much that follows4 ,there was a time 7and that not many decades ago7 when all things1 the origin of which transcends our ordinary experience1 were supposed to have originated suddenly and without natural process--to have been made at once1 out of hand4 ,there was a time when1 for example1 mountains were supposed to have been made at once1 with all their diversified forms1 of beetling cliffs and thundering waterfalls1 or gentle slopes and smiling valleys1 just as we now find them4 ,but now we know that they have become so only by a very gradual process1 and are still changing under our very eyes4 ,in a word1 they have been formed by a process of evolution4 ,we know now the date of mountain-births2 we trace their growth1 maturity1 decay1 and death2 and find even1 as it were1 the fossil bones of extinct mountains in the crumpled strata of their former places4 ,there was a time when continents and seas1 gulfs1 bays1 and rivers1 were supposed to have originated at once1 substantially as we now see them4 ,now1 we know that they have been changing throughout all geological time1 and are still changing4 ,not1 however1 change back and forth in any direction indifferently and without goal1 but gradual change from less perfect to more perfect condition1 with more and more complex inter-relations--i4 e41 by a process of evolution4 ,we are able now1 though still imperfectly1 to trace some of the stages of this evolution4 ,there was a time when rocks and soils were supposed to have been always rocks and soils2 when soils were regarded as an original clothing made on purpose to hide the rocky nakedness of the new-born earth4 ,god clothed the earth so1 and there an end4 ,now we know that rocks rot down to soils2 soils are carried down and deposited as sediments2 and sediments re-consolidate as rocks--the same materials being worked over and over again1 passing through all these stages many times in the history of the earth4 ,in a word1 there was a time when it was thought that the earth with substantially its present form1 configuration1 and climate1 was made at once out of hand1 as a fit habitation for man and animals4 ,now we know that it has been changing1 preparing1 becoming what it is by a slow process1 through a lapse of time so vast that the mind sinks exhausted in the attempt to grasp it4 ,it has become what it now is by a process of evolution4 ,the same change of view has taken place concerning the origin of all the heavenly bodies4 ,we may1 therefore1 confidently generalize--we may assert without fear of contradiction that all inorganic forms1 without exception1 have originated by a process of evolution4 ,the proof of all this we owe to geology--a science born of the present century4 ,this science establishes the law of universal continuity of events1 through infinite time1 as astronomy does that of universal inter-relation of objects through infinite space4 ,how great the change these two sciences have made in the realm of human thought6 ,until the birth of modern astronomy the intellectual space-horizon of the human mind was bounded substantially by the dimensions of our earth2 sun1 moon1 and stars1 being but inconsiderable bodies circulating at a little distance about the earth1 and for our behoof4 ,astronomy was then but the geometry of the curious lines traced by these wandering fires on the concave blackboard of heaven4 ,with the first glance through a telescope the phases of ,venus and the satellites of ,jupiter1 revealed clearly to the mind the existence of other worlds besides and like our own4 ,in that moment the idea of infinite space1 full of worlds like our own1 was for the first time completely realized1 and became thenceforward the heritage of man4 ,in that moment the intellectual horizon of man was infinitely extended4 ,so also until the birth of geology1 about the beginning of the present century1 the intellectual time-horizon of the human mind was bounded by six thousand years4 ,the discovery about that time of vertebrate remains1 all wholly different from those now inhabiting the earth1 revealed the existence of other time-faunas1 besides our own and the idea of infinite time1 of which the life of humanity is but an epoch1 was born in the mind of man2 and again the intellectual horizon of man was infinitely extended4 ,these two are the grandest ideas1 and their introduction the grandest epochs1 in the intellectual history of man4 ,we have long ago accepted and readjusted our mental furniture to the requirements of the one1 but the necessary readjustment to the other is not yet complete4 ,all inorganic forms1 then1 it is admitted1 have come by evolution4 ,but how is it with organic or living forms8 ,let us see4 ,every one knows1 because it is within the limits of ordinary experience1 that every individual organism now originates and gradually becomes what we see it1 by a natural process--that is1 by evolution4 ,if1 then1 there be any exception1 it must be only the first of each kind4 ,but what kind8 ,there are many kinds of kinds2 classes1 orders1 families1 genera1 species1 varieties4 ,now1 many of these kinds can be shown to have become what we see them by a gradual process similar1 at least1 to evolution4 ,take for example1 classes4 ,the class of fishes and the class of reptiles are now widely distinct and have little in common except a vertebrate structure2 but1 as already shown1 page #ab1 this extreme difference has not always existed4 ,on the contrary1 the earliest representatives of these two classes so merged into one another that each seemed either4 ,from this common stock the two classes were gradually separated1 each going its own way and becoming more and more widely distinct even to the present day4 ,there can be no doubt1 therefore1 that these two classes1 as we now know them1 have become what they are by a gradual process4 ,again3 ,in the whole realm of ,nature there is not a class more distinctly separate from every other and without intermediate links than birds4 ,but this has not always been so4 ,they have gradually become so4 ,the earliest birds were so reptilian in structure and appearance that if we could see them now we would be in doubt whether we should call them birds or reptiles4 ,birds have gradually separated themselves from the reptilian stem1 becoming more and more bird-like from age to age1 until now1 at last1 the two classes are wholly separated and the intermediate links destroyed4 ,so far as external characters are concerned1 birds may be said to have finally and wholly released themselves from entangling alliance with any other class4 ,classes1 then1 it will be admitted1 have undoubtedly become what we now know them by a very gradual process following laws identical 7as we have already seen1 page #ai7 with the laws of evolution4 ,shall we try orders8 ,of the class ,mammalia there are two well-recognized and widely-distinct orders1 viz41 the ,carnivores and the ,herbivores4 ,we all know how widely diverse these are in form1 in structure1 in habits1 and in food4 ,has it always been so8 ,have these been made so at once8 ,by no means4 ,they have gradually become so4 ,the earliest mammals were neither the one nor the other distinctively4 ,they were omnivores1 completely intermediate in food1 habits1 form1 and structure4 ,from this common stock the two orders have gradually separated1 the carnivores becoming more and more adapted to one mode of life and the herbivores to another1 by a process following the laws of evolution1 as already explained4 ,shall we try families and genera8 ,marsh and ,huxley have shown us how completely the horse family 7,equid7 and the horse-genus 7,equus7 illustrate the process of gradual becoming and the law of evolution4 ,under their guidance1 we see that the earliest traceable ancestor of the horse family1 before it was distinctively a horse family at all1 had on the fore-foot five toes in the ,lower ,eocene1 four toes in the ,upper ,eocene1 and three toes in the ,miocene2 then we see the two side-toes shortening up more and more in the ,pliocene and becoming rudimentary splints1 leaving only one toe in the ,quaternary and present epochs4 ,thus1 the side-splints in the foot of the modern horse tell the story of its three-toed ancestry4 ,similar gradual changes are clearly traceable in size1 shape1 structure of limbs1 of teeth1 and of brain4 ,in all respects the members of the horse family have become more and more horse-like in the course of time4 ,this subject will be taken up and more fully illustrated1 under the head of special evidences1 in a subsequent chapter4 ,we here touch it only sufficiently to illustrate this universal law of gradual becoming4 ,we have taken only a few examples1 but the same is undoubtedly true of all ,taxonomic groups above species4 ,passing over these last for the moment1 we take next races and varieties4 ,these smaller groups are admitted by all to be formed by a natural process1 because not only can we make them artificially1 but all the intermediate links may be found in ,nature4 ,so we have only species remaining4 ,yes2 species are imagined by the old-school naturalist and by the anti-evolutionist of to-day as the ultimate elements of ,taxonomy4 ,this1 then1 is the last ditch upon which the defense of supernaturalism in the realm of ,nature is made4 8,other groups10 they say1 8may have gradually become what they now are by the successive introduction of specific forms according to a preordained plan which is well expressed by the formal laws of evolution4 ,but species are without transition forms4 ,they come in suddenly1 remain unchanged while they continue1 and finally pass out suddenly1 so far as specific characters are concerned4 ,new species come in their places by direct act of creation--by substitution1 not by transmutation40 ,this1 then1 is the last intrenchment4 ,can we give any good evidence of gradual formation of species8 ,i believe we can4 ,first1 then1 it is admitted that we can easily make varieties and races artificially4 ,we will not now describe the process2 we are all familiar with the results1 viz41 the varieties of domestic animals and of useful and ornamental plants2 the extremely different breeds of horses1 cattle1 sheep1 dogs1 pigeons1 etc42 of wheat1 cabbages1 turnips2 of roses1 dahlias1 etc41 etc4 ,no one will doubt that the extreme varieties of any of these1 say greyhound and pug1 if wild1 would be called distinct species1 or even distinct genera4 ,we do not call them so1 for two reasons3 first1 because we see them made2 and1 second1 because we find all intermediate links between them2 and the usual definition of species is that they can not be made1 and they have no intermediate links4 ,thus1 then1 the question is narrowed down to wild species4 ,they say3 8,we take our stand on these0 7surely a very narrow ground for so broad a philosophy74 8,we defy you to show gradual formation with intermediate links40 ,now1 in fact1 by diligent search such intermediate links between well-recognized species have been found in some cases1 especially in birds1 on account of their great power of dispersal4 ,certain forms have long been known from widely-separated regions1 and universally regarded as distinct species1 as distinct as any4 ,then1 by minute examinations of intermediate regions1 a complete series of intermediate forms has been picked up4 ,this has occurred not only in one case but in many cases1 and not in birds only but in many other classes--examples increase with our increasing knowledge4#aa ,the only answer to such evidence is that these are not true species4 ,now1 see the fallacy lurking here6 ,they define species as ultimate elements of taxonomy1 as distinct and without intermediate links1 and then require us to find such intermediate links2 and1 finally1 when with infinite pains some such links are found1 they say3 8,oh6 ,i see2 we were mistaken2 they are only varieties660 ,it is true that naturalists1 when intermediate links are found1 usually put all together as one species1 but this they do purely for the sake of clearness of definition and description4 ,it is freely admitted by the evolutionist that species are now usually distinct and without intermediate links1 these having been destroyed in the struggle for life4 ,this will be fully explained in another chapter4 ,it is also freely admitted that although intermediate links must have existed at one time1 their remains are rarely found4 ,the reason of this will also be explained hereafter4 ,nevertheless1 in some cases1 as already seen1 we do find them still existing4 ,now1 we add that in some cases1 where they no longer exist1 we find them in the form of fossil remains4 ,the most remarkable example of this is found in the gradual changes in the forms of ,planorbis in the fresh-water deposits of ,steinheim1 as shown by the admirable researches of ,hyatt4#ab ,we shall discuss these also more fully in another place4 ,now1 if there be any such links at all1 however rare1 then every objection to the derivative origin of species is removed4 ,perhaps it may be well to make bare mention of another kind of evidence1 viz41 the actual change of species under the eyes1 by the action of change of environment4 ,the different species of the genus ,artemia 7a low form of crustacean7 live in brine-pools4 ,by concentrating the brine of such a pool1 one species 7,a4 salina7 has been observed to change in successive generations into another 7,a4 ,muhlhausenii71 and the latter back again to the former by slow freshening4#ac ,again3 ,the siredon and the amblystoma have always1 until recently1 been regarded as not only distinct species1 but distinct genera of amphibians4 ,siredon was supposed to be a permanent gill-breather1 while amblystoma becomes by metamorphosis a pure air-breather4 ,now1 however1 it is known that the former may change into the latter4 ,but the most curious part of the life-history of these animals1 is that if water be abundant the siredon reproduces freely1 and remains indefinitely a gill-breather2 but if the water dries up it changes into the lung-breathing amblystoma4 ,we do not give this as examples of change of species1 for the change is in the individual life1 and therefore in the nature of metamorphosis1 but as evidence of the power of physical conditions in modifying the development of organic forms and therefore of the manner in which gill-breathers were probably transformed into air-breathers4 ,to sum up3 #a4 ,all inorganic forms1 without exception1 have become what we find them by a natural process--i4 e41 by evolution4 #b4 ,all organic or living forms within the limits of observation1 i4 e41 every living thing1 has become what we now see1 by a gradual1 natural process--i4 e41 by evolution4 #c4 ,all taxonomic groups1 except species1 have undoubtedly become what we now see them by a gradual process1 following the laws of evolution1 and therefore presumably by a natural process of evolution4 #d4 ,by artificial means1 breeds1 races1 etc41 very similar1 at least in many respects1 to species1 are seen to arise by a gradual natural process--i4 e41 by evolution4 #e4 ,in some instances1 at least1 natural species are observed to pass into one another by intermediate links in such wise that we are forced to conclude that they have been formed by a natural process4 ,may we not1 then1 safely generalize1 and make the law universal8 ,is not this a sufficient ground for confident induction8 ,even though some facts are still inexplicable1 is that a sufficient reason for withholding assent to a theory which explains so much8 ,in all induction we first establish a law provisionally from the observation of a comparatively few facts1 and then extend it over a multitude of facts not included in the original induction4 ,if it explains these also1 the law is verified4 ,the law of gravitation was first based on the observation of a few facts1 and then verified by its explanation of nearly all the facts of celestial motion4 ,there are some outstanding facts of celestial motion still unexplained1 but we do not1 therefore1 doubt the law of gravitation4 ,the same principle applied in biology ought to establish the law of evolution1 for it also explains all the facts of biology as no other law can4 ,but inductive evidence differs from other kinds of evidence in one respect1 which1 in fact1 constitutes its strength to the scientific1 but its weakness to the popular mind4 ,it is a kind of circumstantial evidence1 but its force does not consist in a few strong circumstances easily appreciated1 such as strike the popular mind1 and force conviction1 but rather in a multitude of small circumstances1 each by itself insignificant1 but all together pointing to one conclusion and demanding one explanation4 ,such evidence is1 indeed1 overwhelming1 but only to the mind that masters it4 ,the evidence for the law of gravitation is literally the whole science of astronomy4 ,so also the evidence for the law of evolution is the whole science of biology4 ,neither of these laws can be proved in a debating society1 but only by a course of study4 ,in the one case the law has been universally accepted--not1 however1 on evidence1 for there are few indeed who appreciate the evidence1 but on the authority of scientific unanimity4 ,in the other case there has not yet been time enough for the already established unanimity to have its full effect4 ,thus much1 we believe1 will be generally admitted as a very moderate claim4 ,evolution is certainly a legitimate induction from the facts of biology4 ,but we are prepared to go much further4 ,we are confident that evolution is absolutely certain4 ,not1 indeed1 evolution as a special theory--,lamarckian1 ,darwinian1 ,spencerian--for these are all more or less successful modes of explaining evolution2 nor evolution as a school of thought1 with its following of disciples--for in this sense it is still in the field of discussion--but evolution as a law of derivation of forms from previous forms2 evolution as a law of continuity1 as a universal law of becoming4 ,in this sense it is not only certain1 it is axiomatic4 ,it is only necessary to conceive it clearly1 to see that it is a necessary truth4 ,this may seem paradoxical to some4 ,i stop to justify it4 ,physical phenomena we all admit follow one another in unbroken succession1 each derived from a preceding1 and giving origin to a succeeding4 ,we call this the law of causation1 and say that it is axiomatic4 ,we might call it a law of derivation4 ,so also organic forms follow one another in continuous chain1 each derived from a preceding and giving origin to a succeeding4 ,we call this a law of derivation4 ,we might call it a law of causation1 and say that it too is axiomatic4 ,the origins of new phenomena are often obscure1 even inexplicable1 but we never think to doubt that they have a natural cause2 for so to doubt is to doubt the validity of reason1 and the rational constitution of ,nature4 ,so also the origins of new organic forms may be obscure or even inexplicable1 but we ought not on that account to doubt that they had a natural cause1 and came by a natural process2 for so to doubt is also to doubt the validity of reason1 and the rational constitution of organic ,nature4 ,the law of evolution is naught else than the scientific or1 indeed1 the rational mode of thinking about the origin of things in every department of ,nature4 ,in a word1 it is naught else than the law of necessary causation applied to forms instead of phenomena4 ,evolution1 therefore1 is no longer a school of thought4 ,the words evolutionism and evolutionist ought not any longer to be used1 any more than gravitationism and gravitationist2 for the law of evolution is as certain as the law of gravitation4 ,nay1 it is far more certain4 ,the nexus between successive events in time 7causation7 is far more certain than the nexus between coexistent objects in space 7gravitation74 ,the former is a necessary truth1 the latter is usually classed as a contingent truth4 ,i have used and may continue to use the term evolutionist1 but if so it is only in deference to the views of many intelligent persons1 who do not yet see the certainty of the law4 ,,chapter ,,ii4 ,,special ,,proofs ,,of ,,evolution4 ,introductory4 ,it will be seen from the preceding chapter that we regard the law of evolution in its wider sense1 viz41 the derivative origin of all forms1 organic or other1 as axiomatic1 and therefore requiring no further proof4 ,among scientific men there is no longer any discussion of the truth of this law1 but only of the theories of the causes of the law4 ,we believe that to the scientific mind there is no other rational mode of looking at the subject of origin of organic forms4 ,to such a mind1 therefore1 all that follows is but the deductive application of that law in the explanation of the phenomena of organic ,nature4 ,but it takes time for the popular mind to readjust itself to new and revolutionary truth4 ,many minds1 even among the most intelligent1 have not yet accepted this as the only rational mode of thought4 ,many men require further special proofs of the derivative origin of organic forms4 ,even to those who accept evolution1 these proofs will be interesting as illustrations of such origin4 ,we will attempt to bring out these proofs under several heads1 the most important of which are3 #a4 ,proofs from morphology1 or the general laws of animal structure2 #b4 ,proofs from embryology2 #c4 ,proofs from geographical distribution of organic forms2 and1 #d4 ,proofs from artificial breeding4 ,the subject is so vast that all we can do is to touch lightly only the most salient points under each of these heads2 for1 as we have already said1 the evidence is really nothing less than the whole science of biology4 ,preparatory to this1 however1 it is necessary to bring out a little more fully than before 7page #bi71 though still only in outline1 the two antagonistic views1 which may be called the old and the new1 or the natural and the supernatural1 of the origin of new organic forms1 especially species4 ,origin of ,new ,organic ,forms2 the ,old ,view briefly stated4--,according to the old-school naturalists1 species are the ultimate elements of taxonomy3 genera1 families1 orders1 etc41 may gradually change their character from age to age1 by the introduction of new species2 but species were supposed to be substantially permanent4 ,it was necessary to have some unit for convenience of description and classification1 and this was found to be the best because most stable4 ,as in nearly all cases of beliefs1 this doctrine was held at first somewhat loosely1 as a provisional and convenient view--as a good working hypothesis--but gradually1 under pressure of controversy1 became more strictly formulated1 and1 as it were1 hardened into a scientific dogma1 especially in the hands of ,agassiz4 ,according to this view1 the first pair or pairs of each specific kind originated we know not how1 but certainly at once in its present form in full perfection1 and1 therefore1 presumably by direct creative act of ,deity2 and then afterward by the law of generation continued to produce others of the same pattern indefinitely4 ,moreover1 the first one or more pairs of each kind multiplied and spread abroad in every direction1 each from its own center of origin1 as far as physical conditions and struggle for life with other species would allow4 ,this idea explains tolerably well the geographical distribution of species as we now find it4 ,for example1 species on different continents are widely different1 because those on each have originated independently where we now find them1 and spread in all directions as far as physical conditions would allow1 but could not reach other continents because of the ocean-barrier4 ,that this is the only reason they are not there1 is shown by the fact that1 if they are carried there1 they usually do perfectly well4 ,even on the same continent1 for the same reason1 species may be very different if separated by impassable barriers such as high mountain-chains or by climate4 ,but wherever one group of species1 originating in one place1 comes in contact on the margin of their range with another group of species originating in another place1 we see no evidence of transmutation of one form into another1 but only substitution of one fully-formed species for another equally fully formed4 ,therefore1 we must conclude that physical conditions may limit the range of a species1 but can not transmute it into another4 ,thus1 to say the least1 many of the facts of geographical distribution are well explained by this idea of creative origin in specific centers and subsequent permanence of specific form4 ,we say many of the facts2 we will show hereafter that not all can be thus explained4 ,but the main question is not of geographical but of geological distribution2 not distribution in space1 but succession in time4 ,species do not continue forever4 ,on the contrary1 they have changed many times in the course of geological history4 ,as conditions become unfavorable1 species die out or become extinct1 and others take their place and carry forward the life and development of the organic kingdom4 ,now1 how do they change8 ,according to this school of thought1 here also1 as in geographical distribution1 they are not transmuted but replaced2 here also physical conditions may destroy a species1 but can not transform it into another4 ,as species die out1 others are created at once1 out of hand and fully formed in their place2 but in accordance with a preordained plan consistently carried out and working ever toward higher and higher conditions4 ,thus1 life is continued on the earth by the alternation of supernatural and natural processes2 by the alternate use of direct and indirect action of ,deity3 direct in the introduction of first pairs1 indirect through the natural process of reproduction in the continuance and multiplication of the species4 ,each species is made according to a pattern in the ,divine mind1 on a sort of intellectual die1 and then continues to reproduce a succession of individuals of the same pattern as if struck from the same die until the die is broken or worn out4 ,another die is made1 of another pattern1 and individuals are struck from this2 and so on1 throughout the whole geological history of the organic kingdom4 ,only1 we must add that the successive dies are made to follow one another according to a plan which is expressed by the three laws already given on page #aa4 ,thus1 the origin of individuals is natural1 the origin of species supernatural2 the making of dies is supernatural1 the coinage is natural4 ,we have stated this view in a too extreme form1 in order to make it clearer4 ,we now1 therefore1 proceed to qualify somewhat4 ,specific types were held1 by writers of this school of thought1 to be substantially but not absolutely unchangeable4 ,successive individuals of the same species were admitted to be not exactly alike4 ,such slight differences were called varieties4 ,it was admitted1 indeed1 that species varied1 but it was believed that such variations in any direction were strictly limited in amount4 ,a species may be compared to a right cylinder standing on end4 ,as such a cylinder may be tilted slightly in one direction or another1 without overthrowing its equilibrium1 the cylinder tending ever to right itself and return to its original position1 so a species may be varied slightly in one direction or another without destroying its integrity1 the species tending ever to return to its normal or typical form4 ,but as the cylinder1 if pushed too far from its normal position1 is overthrown1 so also a species1 if pressed too far in the way of variation from its typical form1 is destroyed1 but not changed into another species4 ,as cylinders may be more or less rigid1 depending upon the breadth of their bases1 so also some species are more rigidly set in their typical form1 and some are more plastic to influences causing variations1 but in all cases there is a limit to the amount of oscillation consistent with integrity4 ,the ,new ,view briefly stated4--,according to ,darwin1 and all biologists of the present day1 species are variable without limit1 if only the causes of change are constant and slow enough in their operation1 and the time long enough4 ,a species must be in harmony with its environment1 for this is the condition of its existence4 ,now1 if the environment change1 the species must tend to change slowly from generation to generation1 so as to readjust its relations in harmony with the changing environment4 ,if the change of environment be slow1 the readjustment may be successful1 and the species will change gradually into another form1 so different that it will be called a different species1 especially if the intermediate gradations be destroyed4 ,if the change in the environment be too rapid1 many species1 especially the more rigid1 will be destroyed1 while the more plastic may survive by modification4 ,thus1 at every step in the evolution of the organic kingdom1 some species have died without issue1 while others have saved themselves by changing into new forms in harmony with the new environment4 ,comparing to a growing tree1 some branches overshadowed die1 while others push on for light1 forming new lateral buds1 and dividing as they grow4 ,by continued divergent change species gradually become genera1 genera families1 etc4 ,thus1 varieties1 species1 genera1 families1 orders1 classes1 etc41 are only different degrees of differences formed all in the same way4 ,varieties are only commencing species1 species commencing genera1 and so on4 ,there is no making and wearing out of dies1 and making of new ones2 the whole process is a natural one--the whole series is genetically connected4 ,in a perfect classification varieties1 species1 genera1 families1 orders1 classes1 etc41 are only different degrees of blood-kinship4 ,so much may be regarded as certain1 and out of the field of discussion among biologists of the present day4 ,it is only in defining this process more accurately1 and especially in the theory of the causes or factors of evolution1 that there are still difference and discussion4 ,the most probable view on this subject we now proceed to give4 ,factors of ,evolution4--,the causes of change or adaptive modification1 or the factors of evolution1 are at least four well known1 and probably many more still unknown3 #a4 ,the physical environment--heat and cold1 dryness and moisture--affects function of organs1 and function affects structure1 and both changed function and changed structure are inherited by offspring1 and so increased from generation to generation1 becoming greater without limit4 #b4 ,increased use or disuse of organs enforced or permitted by change in the environment1 physical or organic1 or both1 induces change in form1 size1 and structure of the organs2 and this change is inherited by the offspring1 and so from generation to generation small differences are integrated until they become great without limit4 ,these two factors were recognized by ,lamarck4 #c4 8,natural selection10 or 8survival of the fittest10 among divergent varieties of offspring4 ,this is the distinctive ,darwinian factor4 ,in the two preceding factors the change is during the individual lifetime1 and reproduction is supposed to transmit it unchanged to the offspring4 ,in this factor1 on the contrary1 the form and structure are supposed to remain unchanged during the individual life1 but for some unknown cause there are slight variations in different directions 7divergent7 in the offspring from the same parents4 ,now1 when we remember that by reproduction the number of individuals tends to increase by geometrical progression1 and that in each generation only a very few 7on an average only two from all the offspring of one pair7 can survive1 it is evident that among these divergent varieties those will most likely survive which are most in harmony with the external environment1 and which possess the most efficient organs of defense or of escape1 or for food-taking4 ,the surviving offspring1 therefore1 will be on the average better in these respects than their parents4 ,it matters not how little better1 for the integration of even infinitesimal improvements from generation to generation will eventually produce any required amount of change4 #d4 ,to the above ,darwin has added also 8sexual selection40 ,in natural selection there is struggle of all for food1 or means of living4 ,in sexual selection there is a struggle among the males for possession of the female1 and the means of procreation4 ,the one is connected with the nutritive appetite1 the other with the reproductive appetite4 ,this mode of selection acts in two ways1 by the law of battle and the law of attractiveness4 ,the strongest or the most attractive males alone1 or mainly1 leave offspring1 which1 of course1 inherit their peculiarities2 and these are increased indefinitely by integration through successive generations1 thus increasing the strength or the beauty4 ,of these two laws1 the law of battle is most conspicuous among mammals1 and the law of attractiveness among birds4 ,it is evident that this factor can not operate among many lower animals which are hermaphroditic1 nor among plants4 ,of these acknowledged factors of evolution1 the first two were known to ,lamarck and the older evolutionists4 ,the third and fourth are distinctively ,darwinian4 ,according to ,darwin1 while all these are operative1 the third is the most powerful2 but ,spencer accords this distinction to the ,lamarckian factors4 ,many ,american zologists take the same view4 ,such until very recently were all the recognized factors of evolution4 ,but1 within the past year 7#ahhf7 has taken place1 it seems to us1 the most important advance in the theory of evolution since ,darwin4 ,it is the suggestion by ,mr4 ,catchpool1#ad and afterward the more full elaboration by ,dr4 ,romanes1 of another factor1 which he calls 8physiological selection40#ae ,the great objections to the sufficiency of the theory of evolution1 as left by ,darwin1 were twofold3 #a4 ,while natural selection accounts completely for the formation of useful structures or adaptive modifications1 and therefore for differences characterizing classes1 orders1 families1 and even genera--for these are all adaptive--it can not so completely account for those constituting species2 for these consist mostly of trivial differences in coloration1 relative proportion of parts1 which are of no perceivable use in the struggle for life1 and therefore could not be preserved and integrated by natural selection4 ,therefore1 according to ,romanes1 natural selection is a theory of origin of adaptive structures rather than of origin of species4 ,comparing to a growing tree1 once admit lateral buds started1 and natural selection completely accounts for the growth in different directions1 and therefore for the profuse ramification2 but the origin of the lateral buds is not explained4 #b4 ,the second difficulty is as follows3 ,such commencing differences as constitute varieties and species not only would not be preserved and integrated by natural selection unless useful1 but would immediately be swamped by cross-breeding with the parental form4 ,but1 as the whole divergence commences in varieties1 evidently it could not commence at all unless this cross-breeding be in some way prevented4 ,this may1 indeed1 be done1 without the assumption of any new factor of evolution1 by migration2 and1 hence1 migration must be regarded as an important agent in the creation of new forms1 not only by the effect of a new environment1 but also by prevention of the swamping of commencing species by cross-breeding with the parental form2 but in a crowded locality1 without outlet for migration 7the very conditions most favorable for severe competitive struggle1 and therefore for most potent operation of natural selection2 and therefore1 also1 according to ,darwin1 for profuse diversification71 commencing varieties could not pass into species1 because swamped by cross-breeding4 ,once the divergence reaches the point of cross-sterility--i4 e41 of species--then1 indeed1 by true breeding1 characters1 even though not useful1 may be preserved4 ,but how is it to commence8 ,this difficulty has been severely felt by all ,darwinists4 ,it seems to us that it is largely met by ,dr4 ,romanes4 ,according to ,romanes1 no organ is so subject to varietal changes as the reproductive1 and these in no respect so much as in degrees of fertility4 ,unfortunately1 these changes are not visible1 and must be judged of only by the results4 ,it is not uncommon1 for example1 to find sterility between individuals 7sexual incompatibility7 who are both of them perfectly fertile with other individuals4 ,similarly1 cross-sterility1 partial or complete1 is not uncommon between varieties or races1 as ,mr4 ,darwin has long ago noticed4 ,it very generally1 as we know1 occurs between1 and1 in fact1 is constantly used as a test of1 species4 ,now1 this cross-sterility with parent stock1 which we find so constant a character of species1 and which1 therefore1 must have commenced as a partial cross-sterility in varieties1 is it antecedent or consequent to other variations8 ,it has been usual to suppose it consequent to a certain amount of divergence1 viz41 that which constitutes1 or at least approaches1 species4 ,but1 according to ,romanes1 it is antecedent4 ,among many other variations1 this is that one which originates species1 because it prevents reversion by cross-breeding with the parent stock1 and insures true breeding with its own kind4 ,in a word1 it sexually isolates the species4 ,suppose1 then1 a species multiplying indefinitely in one locality3 trivial variations of many kinds1 and in many directions1 occur among the offspring4 ,these are merged by cross-breeding into the original type1 which1 therefore1 remains unchanged4 ,but1 from time to time1 among these variations there occur some affecting the reproductive organs in such wise as to produce partial or complete cross-sterility with the parent form4 ,this is the beginning of a new species4 ,it breeds true with its own kind1 and therefore all the associated variations external and visible1 and therefore constituting species1 although trivial and of no use in the struggle for life1 are preserved4 ,this view completely accounts for the cross-fertility of artificial breeds equivalent in other respects to species2 for cross-sterility is not an end aimed at by the breeder1 it being easy to prevent cross-breeding1 if desired1 by artificial isolation4 ,but1 if this view be true1 species from widely-different geographical regions ought also to be often cross-fertile1 because1 having been formed by geographical isolation1 sexual isolation was not a necessary factor in their formation4 ,this point deserves testing by careful observation4 ,it may be1 and has been1 objected to ,dr4 ,romanes's claims1 that this is no new factor2 that physiological selection is only a form of natural selection4 ,this objection1 it seems to us1 is little more than a play upon words4 ,it certainly is selection1 and by a natural process1 and therefore in some sense a natural selection1 but not in the sense of ,darwin4 ,it is not a selection of individuals fittest to survive2 for cross-fertile individuals are as fit to survive as individuals1 though not as species1 as are cross-sterile4 ,natural selection is intent only on preserving the best individuals2 physiological selection on preserving the kind4 ,natural selection continues the direction of progress unchanged2 physiological makes new directions4 ,in addition to all these factors of organic evolution1 there is still another far higher factor characteristic of man alone4 ,this is the conscious1 voluntary co-operation of the thing evolving--the spirit of man--in the work of its own evolution4 ,this may be called the rational factor4 ,this1 the most important factor of human evolution1 is usually ignored by writers on evolution--either as non-existent1 or else as lying beyond the domain of science4 ,we will emphasize its importance by taking it up more fully in the next chapter4 ,it will be observed that ,darwin and his followers take divergent variations of offspring simply as a known fact1 upon which natural selection operates to produce progressive modification2 and1 as the cause of variation in offspring is wholly unknown1 such variations are often spoken of as fortuitous4 ,but1 of course1 it is well understood that nothing in ,nature is really fortuitous4 ,they may1 however1 for all purposes of natural selection be thus regarded until we know their cause4 ,it is evident1 then1 that if we1 with ,darwin1 take natural selection1 as the most important known factor1 the really most important cause of evolution is the cause of varieties4 ,this is the unknown fundamental factor4 ,as ,darwin reduced ,agassiz's three formal laws of succession to more general laws of life1 and thus made one important step in the advance of biological science1 so he who shall explain the cause of divergent variation will make another important step by reducing the phenomena to still more general and fundamental laws of life4 ,in conclusion1 let me again impress upon the reader that all the doubt and discussion1 above described1 as to the factors of evolution1 is entirely aside from the truth of evolution itself1 concerning which there is no difference of opinion among thinkers4 ,,chapter ,,iii4 ,,the ,,grades ,,of ,,the ,,factors ,,of ,,evolution ,,and ,,the ,,order ,,of ,,their ,,appearance4 ,we have given in the previous chapter six factors of evolution--viz43 #a4 ,pressure of the environment4 #b4 ,use and disuse of parts4 #c4 ,natural selection4 #d4 ,sexual selection4 #e4 ,physiological selection4 #f4 ,reason4 ,let us now compare these as to their grade in the scale of energy and as to the order of their introduction4 ,the first two or the ,lamarckian factors are the lowest in position1 the most fundamental and universal1 and therefore the first in the order of appearance4 ,they precede all other factors1 and were doubtless for a long time the only ones in operation4 ,for1 observe1 all the selective factors--i4 e41 those of ,darwin and ,romanes--are conditioned on reproduction2 for the changes produced by these are not in the individual during life1 but in the offspring at birth4 ,and not only so1 but the operations of these factors are further conditioned on sexual modes of reproduction2 for all the non-sexual modes of reproduction--as1 for example1 by fissure and by budding--are but slight modifications of growth1 and the resulting multitude of organisms may be regarded as in some sense only an extension of the first individual4 ,of course1 therefore1 the identical characters of the first individual are continued indefinitely1 except in so far as they are modified in successive generations by the effect of the environment and by use and disuse--i4 e41 by the ,lamarckian factors4 ,in sexual generation1 on the contrary1 the characters of two diverse individuals are funded in a common offspring2 and the same continuing through successive generations1 it is evident that the inheritance in each individual offspring is infinitely multiple4 ,now1 the tendency to variation in offspring is in proportion to the multiplicity of the inheritance3 for among the infinite number of slightly differing characters1 as it were1 offered for inheritance in each generation1 some individuals will inherit more of one and some more of another character4 ,in a word1 sexual reproduction by multiple inheritance tends to variation of offspring1 and thus furnishes material for natural selection4#af ,thus1 then1 ,i repeat1 all the selective factors are absolutely dependent on sexual modes of reproduction4 ,but there was a time when this mode of reproduction did not yet exist4#ag ,the sexual modes developed out of non-sexual modes4 ,if these non-sexual preceded sexual modes of reproduction1 it is evident that at first only ,lamarckian factors could operate4 ,evolution was then carried forward wholly by changes in the individual produced by environment and by use and disuse 7acquired characters71 inherited and increased by integration through successive generations indefinitely4 ,it is probable1 therefore1 that the rate of evolution was at first comparatively slow2 unless1 indeed1 as seems probable1 the earliest forms were then and the lowest forms are now more plastic under the influence of physical conditions than are the present higher forms4 ,doubtless1 now1 in the higher animals and plants1 the ,darwinian factors are by far the most potent2 for1 among plants1 where we can use these factors separately1 if we wish to make varieties1 we propagate by seeds 7sexual reproduction72 but1 if we wish to preserve varieties1 we propagate by buds and cuttings 7non-sexual reproduction74 ,i have taken the two ,lamarckian factors together1 and showed that they preceded the ,darwinian4 ,but even in the two ,lamarckian factors there is a difference in grade4 ,undoubtedly the lowest1 the most fundamental1 and therefore the first introduced1 was pressure of the physical environment4 ,for use and disuse of organs implies some degree of volition and voluntary motion1 and therefore already some advance in the scale of evolution4 ,with the introduction of sex another entirely different and higher factor was introduced1 viz41 natural selection1 or selection of the fittest individuals of a varying progeny4 ,we have already seen how sexual generation produces variation of offspring1 and how this furnishes materials for natural selection4 ,as soon1 therefore1 as this form of generation was evolved1 this higher factor came into operation and immediately assumed control2 while the previous factors became subordinate1 though still underlying1 conditioning1 and modifying the activity of the higher4 ,the result was an immediate increase in the rate of evolution4 ,it is very worthy of note that it is in the higher animals1 such as birds and mammals1 in which we have only the highest forms of sexual reproduction1 where the diversity of characters of the two sexes funded in the offspring is the greatest1 and where1 therefore1 the variation in offspring is also greatest and natural selection most active2 it is precisely among these that the ,lamarckian factors are most feeble1 because1 during the most plastic period of life1 the offspring is removed from the influence of the physical environment1 and from use and disuse by its inclosure within the womb1 or within a large egg surrounded with abundant nutriment4 ,development is already well advanced before ,lamarckian factors can operate at all4 ,next1 ,i suppose1 physiological selection1 or ,romanes's factor1 came into operation4 ,after the introduction of sex1 it became necessary that the individuals of some varieties should be isolated in some way1 so as to prevent the swamping of varietal characters1 as fast as formed1 in a common stock1 by cross-breeding4 ,in very low forms1 with slow locomotion1 such isolation might easily take place accidentally4 ,even in higher forms1 changes in physical geography or accidental dispersion by winds and currents would often produce geographical isolation1 and thus1 by preventing crossing with the parent stock1 secure the formation of new species from such isolated varieties4 ,but1 in order to insure in all cases the preservation of commencing species1 sexual isolation1 or partial or complete infertility of some varieties with other varieties and with the parent stock1 was introduced1 as ,i suppose1 later4 ,the process by which this takes place has already been explained4 ,according to ,romanes1 natural selection alone1 with cross-breeding1 tends to monotypal evolution2 isolation of some kind is necessary for polytypal evolution4 ,the tree of evolution1 under the influence of natural selection alone1 grows1 palm-like1 from its terminal bud2 isolation of varieties was necessary for the starting of lateral buds1 and thus for the profuse ramification which is its most conspicuous character4 ,next1 ,i suppose1 was introduced sexual selection1 or contest among the males1 by battle or by display1 for possession of the females1 and the success of the strongest or the most attractive2 and the perpetuation and increase of these superior qualities of strength and beauty in the next generation4 ,this1 ,i suppose1 was later1 because connected with a higher development of the psychical nature4 ,this is especially true where splendor of color or beauty of song determines the selection4 ,as might be supposed1 therefore1 this factor is operative only among the highest animals1 especially birds and mammals4#ah ,next and last1 and only with the appearance of ,man1 another entirely different and far higher factor was introduced1 viz41 conscious1 voluntary co-operation in the work of his own evolution--a conscious1 voluntary striving to attain an ideal4 ,we have called this a factor1 but it is much more than a mere factor1 co-ordinate with other factors4 ,it is1 rather1 a different kind of evolution4 ,it is evolution on a higher plane and by another nature4 ,as physical ,nature works unconsciously1 using certain factors1 so spiritual nature works consciously1 co-operating and using the same factors4 ,at first this factor1 if we still call it so1 was extremely feeble4 ,in the early stages of his progress1 man1 like other animals1 was largely urged on by forces of organic evolution1 unknowing and uncaring whither he tended4 ,but more and more1 as civilization advances1 this higher and distinctively human factor becomes more and more dominant1 until now1 in civilized communities1 it takes control of evolution4 ,reason1 instead of ,nature1 now assumes control1 though still using the methods and factors of ,nature4 ,this free1 self-determined evolution of the race1 in order to distinguish it from the necessary evolution of the organic kingdom1 we call progress4 ,now1 in this whole process we observe two striking stages4 ,the one is the introduction of sex1 the other is the introduction of reason4#ai ,they may be compared to two equally striking stages in the development of the individual4 ,as the ontogenic evolution receives fresh impulse at the moment of fertilization1 so the evolution of the organic kingdom receives fresh impulse at the moment of introduction of sex4 ,as in ontogenic evolution the individual at birth enters upon a new and higher plane1 in which it co-operates in its own physical growth1 so the organic kingdom1 with the introduction of man1 enters upon a new and higher plane1 in which man co-operates in the physical and spiritual growth of the race4 ,with sex three new and higher factors were introduced1 and these immediately assumed control and quickened the rate of evolution4 ,with reason another and infinitely higher factor is introduced1 which1 in its turn1 assumes control1 and not only again quickens the rate1 but elevates the whole plane of evolution4 ,moreover1 this voluntary1 rational factor not only takes control itself1 but transforms all other factors and uses them in a new way and for its own higher purposes4 ,this last is by far the greatest change which has ever occurred in the history of evolution4 ,in organic evolution ,nature operates by necessary law without the conscious voluntary co-operation of the thing evolving4 ,in human progress man voluntarily co-operates with ,nature in the work of evolution1 and even assumes to take the process mainly into his own hands4 ,organic evolution is by necessary law1 human progress by free or at least by freer law4 ,organic evolution is by a pushing upward and onward from below and behind1 human progress by a drawing upward and onward from above and in front by the attractive force of ideals4 ,in a word1 organic evolution is by the law of force1 human evolution by the law of love4 ,it may be well to stop a moment and show briefly some of the differences between organic and human evolution--differences which are1 of course1 wholly the result of the introduction of this new factor3 #a4 ,in organic evolution 8the fittest0 are those most in harmony with the physical environment1 and therefore they survive4 ,in human evolution the fittest are those most in harmony with the ideal1 and often1 especially in the early stages1 when the race is still largely under the dominion of organic factors1 they do not survive1 because not in harmony with the social environment4 ,but1 although the fittest individuals may indeed perish1 the ideal survives in the race and will eventually triumph4 #b4 ,in organic evolution the weak1 the sick1 the helpless1 the unfit in any way perish and ought to perish1 because this is the most efficient way of strengthening the blood or physical nature of the species1 and thus of carrying forward evolution4 ,in human evolution the weak1 the helpless1 the sick1 the old1 the unfit in any way are sustained and ought to be sustained1 because sympathy1 love1 pity1 strengthen the spirit or moral nature of the race4 ,but let us remember that in this material world of ours and during this earthly life the spirit or moral nature is conditioned on the physical nature2 and1 therefore1 in all our attempts to help the weak we must be careful to avoid poisoning the blood and weakening the physical vigor of the race by inheritance4 ,this gravest of social problems1 viz41 ,how shall we obey the higher law of love and mutual help without weakening the blood of the race by inheritance and the spirit of the race by removing the necessity of self-help8--this problem1 ,i believe1 can and will be solved by a rational education1 physical1 mental1 and moral4 ,i only allude to this4 ,it is too wide a field to follow up here4 #c4 ,in organic evolution the bodily form and structure must continually change in order to keep in harmony with the ever-changing environment4 ,in other words1 organic evolution is by continual change of species1 genera1 families1 etc4 ,there must be continual evolution of new forms by modification4 ,in human evolution1 on the contrary1 and more and more as civilization advances1 man modifies the environment so as to bring it into harmony with himself and his wants1 and therefore there is no necessity of change of bodily form and structure or making of new species of man4 ,human evolution is not by modification of form--new species2 but by modification of spirit--new planes of activity1 higher character4 ,and the spirit is modified and character elevated1 not by pressure of an external physical environment1 but by the attractive force of an internal spiritual ideal4 #d4 ,the way of evolution toward the highest--i4 e41 from protozoan to man and from lowest man to the ideal1 the divine man--is a very straight and narrow way1 and few there be that find it4 ,in the case of organic evolution it is so straight and so narrow that any divergence therefrom is fatal to upward movement toward man4 ,once get off the track1 and it is impossible to get on again4 ,no living form of animal is on its way manward1 or can by any possibility develop into man4 ,they are all gone out of the way4 ,there is none going right2 no1 not one4 ,the organic kingdom developing through all geological times may be compared to a tree whose trunk is deeply buried in the lowest strata1 whose great limbs were separated in early geological times1 whose secondary branches diverged in middle geological times1 and whose extreme twiglets1 and also its graceful foliage1 its beautiful flowers1 and luscious fruits1 are the fauna and flora of the present day4 ,but this tree of evolution is an excurrent stem1 continuous through the clustering branches to the terminal shoot--man4 ,once leave the stem as a branch1 and it is easy to continue growing in the direction chosen1 but impossible to get back on the straight upward way to the highest4 ,in human evolution1 whether individual or racial1 the same law holds1 but with a difference4 ,if individual or race gets off the straight1 narrow way toward the highest--the divine ideal--it is hard1 very hard to get back on the track4 ,hard1 ,i say1 but not impossible1 because man's conscious voluntary effort is the chief factor in his own evolution4 ,by virtue of self-activity1 through the use of reason and co-operation in the work of evolution1 man alone of all created things is able to rectify an error of direction and return again to the deserted way4 #e4 ,in organic evolution1 when a higher factor appears1 it immediately assumes control1 and previous lower factors sink into a subordinate position1 though still underlying and conditioning the higher4 ,but in human evolution1 the higher rational factor1 when it comes in with man1 not only assumes control1 but transforms all other factors and uses them in a new way and for its own higher purposes4 ,in fact1 as already said1 it is much more than a mere factor4 ,it determines a new kind of evolution--evolution on a new and higher plane though1 indeed1 underlaid and conditioned by the laws of organic evolution4 ,as external physical ,nature uses many factors to carry forward organic evolution1 so the internal spiritual nature1 characteristic of man alone1 uses these same factors in a new way to carry forward human evolution or progress4 ,thus1 for example1 one organic factor--the environment--is modified or even totally changed so as to effect suitably the human organism4 ,this is hygiene4 ,again1 use and disuse--another factor--is similarly transformed4 ,the various organs of the body and faculties of the mind are deliberately used in such wise and degree 7determined by reason7 as to produce the highest efficiency of each part and the greatest strength and beauty of the whole4 ,this is education--physical1 mental1 moral4 ,so also the selective factors are similarly transformed1 and natural selection becomes rational selection4 ,we all know how this method is applied to domestic animals and cultivated plants in the formation of useful or beautiful varieties4 ,why should it not be applied also to the improvement of our race in the selection of our mates in marriage1 or in the selection of our teachers1 our law-makers1 our rulers8 ,alas6 how little even yet does reason control our selection in these matters6 ,how largely are we yet under the law of organic evolution6 ,application of these principles to some questions of the day3 ,i4 ,evolution1 as a law of derivation of organic forms from previous forms by descent with modifications1 as already shown1 is as certain as the law of gravitation4 ,this question has passed beyond the realm of doubtful discussion2 but the causes1 the factors1 the details of the process of evolution are still under discussion4 ,both ,darwin and ,spencer1 the two great founders of the theory of evolution in its modern form1 acknowledge and insist on at least four factors1 viz41 the two ,lamarckian and the two distinctively ,darwinian4 ,the only difference between them is in the relative importance of the two sets3 ,spencer regarding the former and ,darwin the latter as the more potent4 ,but in these latest times there has arisen a class of biologists1 including some of highest rank1 such as ,wallace1 ,weismann1 and ,lankester1 who out-,darwin ,darwin himself in their exaltation of the most distinctive ,darwinian factor1 viz41 natural selection4 ,they try to show that natural selection is the sole and sufficient cause of evolution2 that changes in the individual1 whether as the effect of the environment or by use and disuse of organs1 are not inherited at all2 that ,lamarck was wholly wrong2 that ,darwin 7in connection with ,wallace7 was the sole founder of the true theory of evolution2 and1 finally1 that ,darwin himself was wrong only in making any terms whatever with ,lamarck4 ,this view has been called ,neo-,darwinism4 ,perhaps the reasons for this view have been most strongly put by ,weismann1 and are based partly on experiments1 but mainly on his ingenious and now celebrated theory of the immortality of germ-plasm4 ,the animal body consists of two kinds of cells wholly different in function--somatic cells and germ-cells1 including in this last the sexual elements both male and female4 ,somatic cells are specially modified for the various functions of the body2 germ-cells are wholly unmodified4 ,the somatic cells are for the conservation of the individual life1 the germ-cells for the conservation of the species4 ,in the development of the egg the germ-cell multiplies itself into a cell-aggregate1 and then most of the resulting multitude of cells are modified in various ways to form the tissues and organs of the body--somatic cells2 but a few are reserved and put aside in an unmodified form in the sexual organs as germ-cells1 to again produce ova which again divide into somatic and germ-cells1 and so on indefinitely4 ,now1 according to ,weismann1 inheritance is only through germ-cells1 while the environment affects only the somatic cells4 ,therefore changes produced by the environment can not be inherited4 ,sexual modes of generation were introduced for the purpose of producing variability in progeny1 and thus furnishing material for natural selection1 as this was the only means of evolutionary advance4 ,weismann made many experiments on animals1 especially by mutilation1 to show that somatic changes are not inherited4 ,a full discussion of this question would be unsuitable in a work like this4 ,we will therefore content ourselves with making three brief remarks3 a4 ,if the views presented in the early part of this chapter are true1 then the ,lamarckian factors must be true factors1 because there was a time when there were no others4 ,they were therefore necessary1 at least to start the process1 even if no longer necessary at present4 b4 ,but if these factors were ever operative1 they must be so still1 though possibly in a subordinate degree4 ,a lower factor is not abolished1 but only becomes subordinate to a higher when the latter is introduced4 ,thus it may well be that ,lamarckian factors are comparatively feeble at the present time and among living species1 especially of the higher animals1 and yet not absent altogether4 ,in the earliest stages of evolution there was a complete identification of germ-cells and somatic cells--of the individual with the species4 ,in such cases1 of course1 any effect of the environment must be inherited and increased from generation to generation4 ,but the differentiation of the germ and somatic cells was not all at once1 nor is their sympathetic relation completely severed4 ,it was a gradual process1 and therefore the effect of the environment on the germ-cells through the somatic cells continued1 though in decreasing degree1 and still continues4 ,the differentiation in the higher animals is now so complete that germ-cells are probably not at all affected by changes in somatic cells1 unless these changes are long continued in the same direction1 and are not antagonized by natural selection4 c4 ,it is a general principle of evolution that the law of the whole is repeated with modifications in the part4 ,this is a necessary consequence of the unity of ,nature4 ,we ought to expect1 therefore1 and do find1 that the order of the use of the factors of evolution is the same in the evolution of the organic kingdom1 in the evolution of each species1 and in the evolution of each individual4 ,in all these the physical factors are at first powerfully operative2 these become subordinate to organic factors1 and these1 in their turn1 to psychical and rational factors4 ,therefore1 as the individual in its early stages--i4 e41 in embryo and infancy--is peculiarly plastic under the influence of the physical environment1 and afterward becomes more and more independent of these2 so a species when first formed is more plastic under the influences of ,lamarckian factors1 and afterward becomes more rigid to the same4 ,and so also the organic kingdom was at first more plastic under ,lamarckian factors1 and has become less so in the present species1 especially in the higher animals4 ,the principal reason of this1 as we have already seen1 is the increasing differentiation of germ and somatic cells1 and the removal of the former to the interior1 where they are more and more protected from external influence4 ,,ii4 ,some evolutionists--the materialistic--insist on making human evolution identical in all respects with organic evolution4 ,this1 we have shown1 is not true4 ,the very least that can be said is that a new and far more potent factor is introduced with man1 which modifies greatly the process4 ,but we may claim much more1 viz41 that evolution is here on a different and higher plane4 ,the factors of organic evolution are1 indeed1 still present1 and condition the whole process2 but they are not left to be used by ,nature alone4 ,on the contrary1 they are used in a new way and for higher purposes--by reason4 ,but by a revulsion from the materialistic extreme some have gone to the opposite extreme4 ,they would place human progress and organic evolution in violent antagonism1 as if subject to entirely different and even opposite laws2 but we have also shown that1 although the distinctive human factor is indeed dominant1 yet it is underlaid and conditioned by all the lower factors2 that these lower factors are still necessary as the agents used by reason4 ,,iii4 ,we have already given the views of ,weismann and ,wallace1 and some reasons for not accepting them2 but there is one important aspect not yet touched4 ,there are some logical consequences of these views when applied to human evolution which seem to us nothing less than a reductio ad absurdum4 ,this brings into view still another contrast between organic evolution and human progress4 ,in organic evolution1 when the struggle for life is fierce and pitiless as it is now among the higher animals1 natural selection is undoubtedly by far the most potent factor4 ,it is at least conceivable 7though not probable7 that at the present time organic evolution might be carried on mainly or even wholly by this factor alone2 but in human evolution1 especially in civilized communities1 this is impossible4 ,if ,weismann and ,wallace be right1 then alas for all our hopes of race improvement--physical1 mental1 and moral6--for natural selection will never be applied by man to himself as it is by ,nature to organisms4 ,his spiritual nature forbids4 ,reason may freely use the ,lamarckian factors of environment and of use and disuse1 but is debarred the unscrupulous use of natural selection as its only method4 ,as this is an important point1 we must explain4 ,all enlightened schemes of physical culture and hygiene1 although directed primarily to secure the strength1 the health1 and the happiness of the present generation1 yet are sustained and ennobled by the conviction that the improvement of the individuals of each generation enters by inheritance into the gradual physical improvement of the race4 ,all our schemes of education1 intellectual and moral1 though certainly intended mainly for the improvement of the individual1 are glorified by the hope that the race also is thereby gradually elevated4 ,it is true that these hopes are usually extravagant2 it is true that the whole improvement of one generation is not carried over by inheritance into the next2 it is true1 therefore1 that we can not by education raise a lower race up to the plane of a higher in a few generations or even in a few centuries3 but there must be at least a small residuum1 be it ever so small1 carried forward from each generation to the next1 which1 accumulating from age to age1 determines the slow evolution of the race4 ,such are the hopes on which all noble efforts for race-improvement are founded4 ,are all these hopes baseless8 ,they are so if ,weismann and ,wallace are right4 ,if it be true that reason must direct the course of human progress1 and if it be true also that selection of the fittest in the organic sense is the only method which can be used by reason1 then the dreadful law of pitiless destruction of the weak1 the helpless1 the sick1 the old1 must with ,spartan firmness be voluntarily and deliberately carried out4 ,against such a course we instinctively revolt with horror1 because contrary to the law of our spiritual nature4 ,but the use by reason of the ,lamarckian factors is not attended with any such revolting consequences4 ,all our hopes of race-improvement1 therefore1 are strictly conditioned on the efficacy of these factors--i4 e41 on the fact that useful changes1 determined by education in each generation1 are to some extent inherited and accumulated in the race4 ,,chapter ,,iv4 ,,special ,,proofs1 ,,taken ,,from ,,the ,,general ,,laws ,,of ,,animal ,,structure1 ,,or ,,from ,,comparison ,,in ,,the ,,taxonomic ,,series4 ,general ,principles4 ,analogy and ,homology4--,in biology those organs or parts in different animals are said to be analogous which1 however different their origin1 have a general similarity of form and especially of function2 while those are called homologous which1 however different their general appearance1 and however different their function1 yet may1 by close examination and extensive comparison1 be shown to be modifications of one another--to be1 in fact1 originally the same part modified for different purposes4 ,in the former the parts compared look and behave as if they were the same1 but are not2 in the latter they look and behave entirely differently1 but are1 in fact1 the same part in disguise4 ,we can best make this plain by examples4 ,the wing of a bird and the wing of a butterfly are analogous organs4 ,they have the same function--i4 e41 flying2 and this function necessitates the same general form of a flat plane4 ,but they are not at all homologous2 they are not at all the same organ or part4 ,they certainly have never been formed one out of the other by modification4 ,but the wing of a bird1 the fore-paw of a reptile or mammal1 the wing of a bat1 and the arm and hand of a man1 though so different in form and function1 are homologous parts4 ,on close examination they are found to have the same general structure1 to be composed of essentially the same pieces1 although they are so greatly modified in order to adapt them to different functions1 that the general or superficial resemblance is now lost4 ,their structure is precisely such as it would be if they had all originated from some archetypal fore-limb by modifications in different directions of its several parts4 ,by extensive comparison in the taxonomic and ontogenic series1 all the intermediate gradations between these extreme modifications may be picked up4 ,illustration3 ,,fig4 #b4--,lepidosiren4 ,another example4 ,the lungs of a mammal and the gills of a fish are analogous organs1 since they have the same function of aration of the blood4 ,but they are not at all homologous3 they are not built on the same plan2 by no effort of the mind can we imagine that the former could have come out of the latter by modification4 ,on the contrary1 we have positive proof that it did not so come4 ,but there is an organ in the fish which is homologous with the mammalian lung1 viz41 the air-bladder1 or swim-bladder4 ,we know it--#a4 ,because we can trace in the taxonomic series all the gradations from the one to the other4 ,in most fishes the air-bladder is wholly cut off from the gullet1 and only very feebly supplied with blood4 ,it is used and can be used only for flotation4 ,in others1 as the gar-pike1 the swim-bladder is quite vascular and opens by a tube into the throat4 ,through this opening air is gulped down from time to time into the bladder1 and again from time to time expelled4 ,in other words1 this fish supplements its gill-breathing by an imperfect lung-breathing4 ,we have here the beginning of a lung4 ,in still other fishes1 viz41 the ,dipnoi 7lepidosiren and ceratodus1 ,fig4 #b71 the air-bladder becomes a more perfect lung--i4 e41 a very vascular sacculated sac2 and there is not only an opening into the throat1 but also from the throat to the snout4 ,in other words1 we have for the first time nostrils4 ,these fishes completely combine gill-breathing with lung-breathing4 ,the step from these to the lowest amphibian reptiles is so small1 that some have classed the lepidosiren among amphibians instead of fishes4 ,the siredon or axolotl of ,new ,mexico1 the necturus or menobranchus of our ,northern lakes1 and the siren of our ,southern swamps1 have both gills and lungs1 and breathe both air and water2 but the lung is very imperfect1 being only a sacculated sac1 like the air-bladder of the ceratodus and lepidosiren4 ,no one doubts that the air-breathing organ of an amphibian is a true lung2 yet we have traced all the gradations between it and the air-bladder of a fish4 ,we conclude1 therefore1 that if there be any such thing as transmutation of organic forms1 the lung of higher animals must have been formed by the process above described4#bj ,but we know it still more certainly--#b4 ,because we can trace the change from the one to the other in the ontogenic series4 ,in the life-history of the individual we can actually see the one thing change into the other4 ,the frog1 as is well known1 when first hatched1 is a tadpole4 ,it has no legs1 but locomotes by means of a vertically-expanded tail4 ,it has no lungs1 but breathes water instead of air1 by means of gills4 ,it is in all respects1 therefore1 a fish1 and would be classed as such if it remained in this condition4 ,but it does not2 it gradually loses its tail and gills1 and acquires legs and lungs1 and breathes air only4 ,now in this change whence came the lungs8 ,from the gills by modification8 ,no2 but from an organ similar in character and position to the air-bladder of a ceratodus1 or a lepidosiren4 ,this organ has gradually developed into a lung4 ,the steps of the change are briefly as follow3 ,first1 the breathing is wholly water-breathing by gills4 ,next1 by the development of this other organ1 it is partly water-breathing by gills1 and partly air-breathing by lungs4 ,lastly1 the gills gradually dry up1 and the lungs develop more and more1 until the breathing is wholly by lungs4 ,we have dwelt somewhat upon this example1 because it is an excellent example of what we mean by homology1 and also because we will have occasion to use it again4 ,but so important1 for all that follows in this part1 is a clear idea on the subject of homology1 that it will be best to familiarize the mind of the reader with it by means of a few examples drawn from plants4 ,a potato is analogous to a root--a tuberous root like that of a dahlia or a sweet-potato--but is not at all homologous with these4 ,on the contrary1 it is homologous with a stem4 ,it is essentially an underground1 leafless branch1 which has thickened enormously at the point by accumulation of starch4 ,the evidence of this is found in the fact that it has rudimentary leaves 7scales7 arranged in regular spiral order of phylotaxis1 each with its axillary bud 7eyes74 ,it is still more clearly shown by the fact that buds above-ground which1 if let alone1 would form leafy branches1 may be made to become tubers by covering them with earth or dead leaves1 and thus excluding the light2 and1 conversely1 underground buds which1 if let alone1 would form tubers1 may be made to grow into leafy branches by exposing them to the light4 ,take another example3 ,the broad1 flat1 elliptical1 green masses so characteristic of the cactus family1 and usually called their leaves1 are indeed analogous to leaves in color1 form1 and function2 for they are green and flat1 and assimilate carbonic acid and water 7,,co#b and ,h#b,o7 like leaves4 ,but they are not1 in truth1 leaves1 but modified stems1 for they have the essential structure of stems1 with their pith1 wood1 medullary rays1 and bark1 and may be traced through all gradations into the ordinary cylindrical form of stems4 ,where are their leaves1 then8 ,their spines are their abortive leaves4 ,these are arranged spirally like leaves1 and bear buds in their axils like leaves4 ,they are1 in truth1 leaves1 modified to perform the function of defensive armor2 while their function has been delegated to the stem flattened for this purpose4 ,illustration3 ,,fig4 #c4--;,a branch of young acacia1 showing change from one form of leaf to the other2 a1 b1 c1 d1 successive stages of change2 l1 s1 leaf stalk which gradually changes into the blade in c1 d1 and e4 ,one more example3 ,the acacias1 of which there are fifteen to twenty species in ,california1 introduced from ,australia1 form two groups having extremely different styles of leaves4 ,we will call them the feather-leaved and the simple-leaved acacias4 ,in the former1 the leaves are very finely bipinnate1 and the general aspect of the foliage is extremely feathery and graceful4 ,in the latter the leaves are simple1 ovate1 and1 curiously enough1 set on edge2 and the general aspect of the tree is therefore rather stiff4 ,it seems at first incredible that leaves so different and aspects so diverse should belong to plants of the same genus4 ,but a little close examination shows that1 as usual1 the botanists are right and the popular judgment wrong4 ,the plumose-leaf is the normal leaf-form for this genus4 ,the simple leaf is not only abnormal1 but in a homological sense is not a leaf at all--i4 e41 it does not correspond to the part called the blade in ordinary simple leaves of other trees4 ,in the seedling of the simple-leaved acacias1 and sometimes for a considerable time in the young tree1 the leaves are all plumose4 ,as the tree matures it gradually changes its dress and puts on its toga virilis4 ,the gradual change from the one form to the other may easily be traced in the same tree1 and even often in the same branch 7,fig4 #c74 ,the steps of the change 7a1 b1 c1 and d7 are shown in the following figure1 drawn from nature4 ,it is seen1 by bare inspection of the figure1 that the so-called leaf1 d1 of the simple-leaved acacias1 is really the vertically-expanded leaf-stalk1 l1 s1 the true leaf or blade being wholly aborted4 ,the whole structure of this so-called leaf is different from that of a true blade4 ,for example1 its style of ribbing is parallel1 its position is edgewise to the sky1 its palisade cells are on both sides alike1 etc4 ,to emphasize this difference1 botanists call such an apparent leaf a phyllodium1 or phyllode4 ,after these illustrations we now repeat the definitions in different words4 ,analogy has reference to general resemblance of form determined by similarity of function1 however different the origins of the parts compared may be4 ,homology has reference to community of origin1 however obscured to the superficial observer such common origin may be by modifications necessary to adapt to different functions4 ,observe1 then1 there are two ideas here which must be kept distinct4 ,one is common origin1 always shown by deep-lying1 essential identity of structure2 the other is adaptive modification for function4 ,organs of the most diverse origin may resemble by adaptive modification for the same function4 ,this is analogy4 ,organs of the same origin may assume very different appearance by adaptive modifications for different functions4 ,this is homology4 ,in the latter case1 which is the one that concerns us1 a profound study of essential structure and structural relations to other parts1 and especially extensive comparison in the taxonomic and ontogenic series1 will usually detect the homology1 or common origin1 in spite of the obscurations produced by adaptive modifications4 ,it is seen1 also1 that analogy is a superficial resemblance1 easily detected by the popular eye1 and therefore embodied in popular language2 while homology is a deep-seated and essential resemblance1 detected often only by profound study and extensive comparison4 ,now1 one of the strongest proofs of the truth of evolution is taken from the homologies of animal structure4 ,common origin completely explains homology4 ,every other explanation is transcendental1 and therefore unscientific4 ,primary ,divisions of the ,animal ,kingdom4--,now1 the animal kingdom consists of several primary divisions1 called sub-kingdoms or departments4 ,the animals in these groups differ so essentially from one another in their plan of structure1 that it is difficult1 if not impossible1 to trace any structural relation between them--to imagine how the members of one could have been derived from those of another--or conceive the common stem from which they all separated4 ,in other words1 it is impossible1 in the present state of knowledge1 to trace homology with any certainty from one group to another4 ,but within the limits of each primary group the homology is easy4 ,some naturalists--,agassiz and ,cuvier--have made four or five of these primary groups4 ,some--,huxley--have made eight4 ,some make nine or ten4#ba ,we will not trouble ourselves to settle this question2 for all agree to make vertebrata and articulata or arthropoda two of them1 and all our illustrations will be drawn from these4 ,other groups are too unfamiliar to the general reader to serve our purpose4 ,now1 as already stated1 homology can not be traced with any certainty between the primary groups1 but within the limits of each group it may be traced with ease and beauty4 ,analogy1 however1 being connected with function1 and function being universal1 can be traced throughout the animal kingdom4 ,while1 therefore1 it is probable1 nay1 almost certain1 that all animals have had a common origin1 we can not yet trace these great departments by homology to that common origin4 ,but the common origin of each department is quite clear4 ,for example1 the structure of all vertebrate animals is precisely such as would be the case if all came from one primal vertebrate1 variously modified to adapt to various modes of life4 ,also1 the structure of all arthropods is precisely such as would be if all came from one primal arthropod1 which1 from generation to generation1 became gradually modified in different directions1 in order to adapt itself to various modes of life4 ,but between arthropods and vertebrates we can not yet clearly see a common origin1 although there doubtless was such4 ,these great departments may1 therefore1 be compared to natural styles of animal architecture4 ,as there are various styles of human architecture--,oriental1 ,egyptian1 ,greek1 ,gothic--each of which may be variously modified to adapt it to all the different purposes for which buildings are made1 without destroying1 though perhaps obscuring1 the integrity of the style2 so the different primary groups or departments may be regarded as different styles of animal structure1 each of which may be and has been modified in many ways to adapt it to various habits and modes of life1 obscuring but not destroying the general style4 ,or they may be compared to natural machines4 ,as a steam-engine1 by modification1 may be adapted to many kinds of purposes1 obscuring1 perhaps1 but not destroying the essential identity of structure2 even so the vertebrate machine by modification may be1 and has been1 adapted to many kinds of purposes1 and thus become a swimming-machine1 a crawling-machine1 a flying-machine1 a running-and leaping-machine1 without destroying1 although obscuring1 the essential identity of structure4 ,as in architecture1 sthetic principles of form may be traced through each style1 but not from style to style1 while the mechanical principles of construction run through all alike2 so also in animal architecture1 the laws of form and styles of structure are traceable with ease only within the limits of each primary group1 while the laws of function are traceable through all groups alike4 ,or1 again1 and finally3 ,each of these departments may be compared to a tree1 with branches1 twigs1 and spray1 all obviously coming from one common stem1 but each stem seems separate4 ,they are1 indeed1 probably1 themselves only great branches of one common trunk1 but their connection is too remote and obscure to be made out clearly by means of homology4 ,other evidences1 however1 drawn from other sources1 as we shall see hereafter1 are not wholly wanting4 ,,chapter ,v4 ,,proofs ,,from ,,homologies ,,of ,,the ,,vertebrate ,,skeleton4 ,the proposition to be established here is1 that all vertebrates have not only a common general plan of structure1 but an essential identity even in detail1 although this identity is obscured by adaptive modifications4 ,we will try to show first a common general plan1 and then1 taking parts most familiar to the general reader1 will show essential identity even in detail4 ,common ,general ,plan4--#a4 ,all vertebrate animals1 and none other1 have an internal jointed skeleton worked by muscles on the outside4 ,as we shall see hereafter1 the relation of skeleton and muscle in arthropods is exactly the reverse4 #b4 ,in all vertebrates1 and in none other1 the axis of this skeleton is a jointed backbone 7vertebral column7 inclosing and protecting the nervous centers 7cerebro-spinal axis74 ,these1 therefore1 may well be called back-boned animals4 #c4 ,all vertebrates1 and none other1 have a number of their anterior vertebral joints enlarged and consolidated into a box to form the skull1#bb in order to inclose and protect a similar enlargement of the nervous center1 viz41 the brain2 and also usually1 but not always1 a number of posterior joints1 enlarged and consolidated to form the pelvis1 to serve as a firm support to the hind-limbs4 #d4 ,all vertebrates1 and none other1 have two cavities1 inclosed and protected by the skeleton1 viz41 the neural cavity above1 and the visceral or body cavity below1 the vertebral column2 so that a cross-section of the body is diagrammatically represented by ,fig4 #d4 ,illustration3 ,,fig4 #d4--;,diagram cross-section through the body of a vertebrate1 showing the relation of skeleton to the cavities4 n1 neutral cavity2 v1 visceral cavity2 c1 centrum of vertebra4 #e4 ,all vertebrates1 with few exceptions1 and no other animals1 have two and only two pair of limbs4 ,the exceptions are of two kinds1 viz43 a1 some lowest fishes1 amphioxus and lampreys1 which probably represent the vertebrate condition before limbs were acquired2 and b1 degenerate forms like snakes and some lizards1 which have lost their limbs by disuse4 ,so much concerns the general plan of skeletal structures1 and is strongly suggestive of--in fact1 is inexplicable without--common origin4 ,but much more remains which is not only suggestive1 but demonstrative of such origin4 ,by extensive comparison in the taxonomic and ontogenic series1 the whole vertebrate structure in all its details in different animals may be shown to be modifications one of another4 ,sometimes a piece is enlarged1 sometimes diminished1 or even becomes obsolete2 sometimes several pieces are consolidated into one2 but1 in spite of all these obscurations1 corresponding parts may usually be made out4 ,this is the main subject of this chapter4 ,special ,homology of ,vertebrate ,limbs4--,it would lead us much too far into unfamiliar technicalities to take up the whole skeleton4 ,we select the limbs1 both because their general structure is more familiar1 and because in them the two fundamental ideas of essential identity and of adaptive modification are both admirably illustrated4 ,the reason of this is1 that it is by the limbs that the organism chiefly reacts on the environment1 and is modified by it4 ,fore-limbs4--,in the accompanying figures 7,figs4 #e-ah7 we have represented1 side by side1 the fore-limbs of many vertebrates1 taken from all the classes--mammals1 birds1 reptiles1 and fishes4 ,for convenience of comparison1 the corresponding parts are similarly lettered in all4 ,also1 in order to identify easily certain important corresponding segments1 we have drawn through them a continuous dotted line4 ,in man1 nearly all the parts are present1 and his limbs1 therefore1 may be taken as a term of comparison2 for man's structure1 except his brain1 is far less modified than that of many animals4 ,note1 then1 the following points3 #a4 ,the collar-bone 7clavicle7 is associated with wide separation of the shoulders1 and the free use of the fore-limb for prehension or for flight1 but is gradually lost in proportion as the fore-limb is brought nearer together and used for support1 because it is no longer wanted4 ,i say gradually1 for all the steps of the passing away may be found4 ,the useless rudimentary condition is not uncommon4 ,illustration3 ,,figs4 #e-i4--e4 ,fore-limb of man4 #f4 ,dog #g4 ,hog4 #h4 ,sheep4 #i4 ,horse4 sc1 scapula2 c1 coracoid2 a1 b1 two bones of fore-arm4 7,taken from various sources and grouped47 ,illustration3 ,,figs4 #aj-ac4--aj4 ,fore-limb of bat4 #aa4 ,bird4 #ab4 ,archopteryx4 #ac4 ,pterodactyl4 7,lettered as in previous figures2 grouped from various sources47 #b4 ,the coracoid 7c71 it is seen1 is a small1 beak-like process of the blade-bone 7scapula7 in man and mammals2 but in birds 7,fig4 #aa7 and reptiles 7,figs4 #ad1 #ah7 it is a separate bone as large as the blade-bone itself1 jointed with the latter at the shoulder and with the breast-bone 7sternum7 in front1 thus making together a strong shoulder-girdle for the attachment of the fore-limb4 ,this was undoubtedly the condition in the original or earliest walking animal1 viz41 reptiles4 ,it was inherited and retained by birds1 because necessary for powerful action of the wings in flight4 ,in mammals it gradually dwindled and became united with the blade-bone as a process4 ,in one mammal1 the lowest and most reptilian living--the ornithorhynchus--the coracoid is much like that of reptiles--a large1 flat bone1 separated from the blade-bone and articulated with the breast-bone4 ,it is a significant fact that1 in the mammalian embryo1 it is first developed as a separate bone and afterward united with the scapula4 ,illustration3 ,,figs4 #ad-ag4--ad4 ,fore-limb of turtle4 #ae4 ,mole4 #af4 ,whale4 #ag4 ,fish4 #c4 ,in man1 monkeys1 bears1 and some other mammals1 the limb is fairly free from the body and the elbow half-way down the limb2 while in herbivores 7,figs4 #h1 #i71 such as the horse1 ox1 and deer1 etc41 the elbow is high on the side of the body1 and the limb is free only from the elbow downward4 ,perhaps in these cases most observers do not recognize it as an elbow at all4 ,all gradations between these extremes are easily traced4 ,the free condition of the limb is evidently the original one1 the condition in herbivores being an extreme modification associated with another modification mentioned under #e4 #d4 ,in man and in many mammals1 and in all reptiles and birds1 there are two bones in the forearm 7radius and ulna74 ,in the more specialized forms of hoofed animals 7ungulates71 such as horse and ruminants 7,figs4 #h1 #i71 there is apparently but one4 ,two is the normal and original number2 but one of them1 the ulna1 has gradually become smaller and smaller1 and finally is reduced to a short splint1 and consolidated with the radius as a process extending backward to form the point of the elbow4 ,in the horse family every step of this reduction and consolidation may be traced in the course of its geological history4 ,illustration3 ,,fig4 #ah4--,mosasaur4 #e4 ,the wrist of many mammals and all birds differs in structure from that of man1 chiefly in containing a smaller number of bones4 ,the normal number1 as in man1 seems to be eight4 ,the decrease takes place mainly by consolidation of two or more into one4 ,in such cases usually the embryo will show the bones still separate1 thus revealing the ancestral condition4 ,again1 the position of the wrist is noteworthy4 ,in man1 monkeys1 the bear family1 and several other mammalian families1 and in all reptiles1 the hand bends forward at the wrist1 so that the tread is on the whole palm 7palmigrade74 ,but1 in all the most specialized mammals1 the wrist can not bend in this direction1 and therefore this joint can not be brought to the ground4 ,the tread is therefore on the toes 7digitigrade71 and the wrist is high up above the ground4 ,in the horse 7,fig4 #i71 the ox1 and many other mammals1 for example1 the wrist is so high that it is not usually recognized as a wrist1 and is often called the fore-knee4 ,now1 homologous parts ought to have the same scientific name2 but to use the word 8hand0 in the case of lower animals might produce confusion and misconception4 ,therefore it has been agreed among comparative anatomists to use instead the ,latin word 8manus0 for all that corresponds1 in any animal1 to the hand of man--i4 e41 all from the wrist downward4 ,the manus of a horse is about fifteen inches long4 ,the manus of a pterodactyl1 such as that found by ,marsh in the cretaceous strata of the ,west1 with an expanse of wings of twenty-five feet1 was probably not less than seven or eight feet long4 #f4 ,the number of palm-bones 7metapodal7 and toes deserves special notice4 ,in fishes1 and in some extinct swimming reptiles1 these are or were very numerous1 but in the earliest land-animals they became five4 ,this is the number now in nearly all reptiles1 and in all the more generalized mammals4 ,it may be called the normal number for a walking animal4 ,in very many mammals1 such1 for example1 as the dog family1 they are reduced to four1 though the fifth often remains as a useless1 rudimentary splint and dew-claw 7,fig4 #f71 thus showing the process of dwindling in the ancestry4 ,in hoofed animals the process of gradual diminution is shown even in existing forms1 and still better in extinct forms4 ,confining ourselves1 now1 only to existing forms1 in the elephant there are five palm-bones and toes1 and in the hippopotamus there are four1 all functional4 ,in the hog 7,fig4 #g7 there are still four1 but two are behind the others and much smaller1 and do not touch the ground--are not functional unless in soft ground4 ,in the cow1 deer1 etc41 the palm-bones are reduced to two1 and these are consolidated into one 7canon-bone71 and the toes are reduced to two efficient and two useless rudiments4 ,in the sheep and the goat 7,fig4 #h7 these useless rudiments are dropped1 and there are two only4 ,finally1 in the horse 7,fig4 #i71 the toes are reduced to one1 although the palm-bones are still three1 two of them1 however1 being reduced to rudimentary splints4 ,how is it with birds8 ,have these also palm-bones and fingers8 ,yes1 in birds 7,fig4 #aa7 there are three palm-bones and three fingers 7the fourth and fifth being wanting72 one of them--the thumb--is free1 and sometimes carries a claw4 ,in the earliest known and most reptilian bird1 the archopteryx 7,fig4 #ab71 all the three fingers are free1 have the full number of joints1 and all of them carry claws4 ,in the embryo of living birds the fingers are all free1 as in the archopteryx4 ,illustration3 ,,fig4 #ai4--,restoration of ,rhamphorhynchus phyllurus 7after ,marsh74 ,one-seventh natural size4 #g4 ,observe1 finally1 as an admirable illustration of different adaptative modifications for the same purpose--flight--the structure of the manus of flying animals4 ,in the bat 7,fig4 #aj71 the flat flying-plane is made by enormous elongation of the palm-bones and finger-bones1 their wide separation and the stretching of a thin membrane between them4 ,in the pterosaurs1 or extinct flying reptiles 7,fig4 #ac71 one finger only is greatly enlarged and elongated1 and the flying-membrane is stretched between it and the hind-leg 7,fig4 #ai71 while the other three fingers are free and provided with claws4 ,if it be asked which finger is it that is so greatly enlarged in this animal1 we answer1 it is the little finger4 ,in birds1 on the contrary1 the manus is consolidated to the last degree1 to form a strong basis for attachments for the quills which form the flying-plane1 and which are themselves extreme modifications of the scales of reptiles4 ,but throughout all these extreme modifications the same essential structure is detectable4 ,it is perhaps unnecessary to dwell upon the still greater modifications of limbs for swimming1 as in the whale 7,fig4 #af71 the ichthyosaur1 mosasaur 7,fig4 #ah71 and the fish 7,fig4 #ag74 ,a careful inspection of the figures1 after what we have said1 will be sufficient to explain them4 ,in the fish alone the upper segments of the limb1 viz41 shoulder-girdle and humerus1 are wanting1 not being yet introduced1 and the manus is not yet differentiated into palm-bones and fingers1 and the fingers are indefinitely multiplied4 ,all these characters are indications of low position in the scale of evolution4 ,the earliest vertebrates were fishes4 ,limbs were not yet completely formed4 ,in embryos of higher animals1 also1 the outer segments are first formed4 ,hind-,limbs4--,figs4 #bj to #bd represent1 in a similar way1 the hind-limbs of several animals--in this case all mammals4 ,as before1 corresponding parts are similarly lettered1 and a dotted line is carried through certain prominent parts1 especially the knee1 heel1 instep1 and toes4 ,by careful inspection the figures explain themselves4 ,nevertheless1 it will be well to draw special attention to several of the more important points3 ,illustration3 ,,figs4 #bj-bd4--bj4 ,hind-limb of man4 #ba4 ,monkey4 #bb4 ,dog4 #bc4 ,sheep4 #bd4 ,horse4 #a4 ,see1 then1 the position of the knee4 ,the thigh-bone in man1 monkeys1 bears1 and several other families of mammals1 and all reptiles1 is free from the body1 and the knee is far removed and half-way down the limb 7,figs4 #bj1 #ba74 ,this is undoubtedly the original and normal condition of land-animals4 ,but in all the more highly specialized and swifter animals the knee is brought nearer and nearer to the body1 until1 in the swiftest of all1 such as the ruminants and the horse 7,figs4 #bc1 #bd71 it is high up on the side of the body1 in the middle of what is usually called the thigh but which really includes the thigh and the upper part of the lower leg or shank4 #b4 ,see1 again1 the position of the heel4 ,in man1 monkey1 bear1 and many other mammals1 and all living reptiles1 the heel is on the ground1 the tread is on the whole foot1 plantigrade2 while in all the more specialized and agile animals1 and especially in the swiftest of all1 such as the horse1 the deer1 etc41 the heel is high in the air1 and the tread is digitigrade4 #c4 ,observe1 again3 there are two degrees of digitigradeness4 ,the one we find in carnivorous or clawed digitigrades1 the other in herbivores or hoofed digitigrades4 ,in the one the tread is on the whole length of the toes to the balls1 as in man when he tip-toes2 in the other the tread is on the tip of the last joint alone4 ,all that in any animal corresponds to the foot of a man--i4 e41 from the hamstring and heel downward--is called1 in comparative anatomy1 the 8pes40 ,the pes1 or foot of a horse1 is eighteen inches long4 ,it is easy to see what spring and activity this mode of treading gives to an animal4 ,think how helpless a horse would be if he trod on the whole foot1 heel down6 #d4 ,observe1 again1 the number of toes4 ,in the process of specialization there is a tendency for these to become fewer and stronger4#bc ,the normal number1 as already seen1 is five4 ,all the earliest mammals1 and many orders of mammals still living1 have five2 but in the most specialized orders1 such as the ungulates or hoofed animals1 they were steadily reduced in number in the course of evolution4 ,in the elephant there are still five1 in the hippopotamus there are four1 in the rhinoceros three1 in the goat two1 in the horse one4 ,still more the order of the dropping is regular4 ,if an animal have but four toes1 it is usually the first1 or great toe1 or thumb1 that is wanting1 or may be rudimentary4 ,if1 as in the rhinoceros1 there are only three1 then ,no4 #e1 or little toe1 is also wanting1 and the existing toes are ,nos4 #b1 #c1 and #d4 ,if an animal has only two toes1 as the goat1 these are ,nos4 #c and #d2 and if only one1 as the horse1 it is the third or middle toe4 ,or1 to put it more definitely3 hoofed animals are divided into two groups1 even-toed 7artiodactyl7 and odd-toed 7perissodactyl74 ,the even-toed may have four1 as in the hippopotamus2 or two1 as in the goat4 ,the odd-toed may have three1 as in the rhinoceros2 or but one1 as in the horse4 ,now1 both of these orders came by differentiation1 far back in the ,eocene ,tertiary1 from a five-toed plantigrade ancestor4 ,after dropping ,no4 #a 7thumb or great toe7 it is not yet decided1 so far as number of toes is concerned1 whether the resulting four-toed animal shall become artiodactyl or perissodactyl4 ,if the former1 then the two side-toes 7,nos4 #b and #e7 become shortened up1 as in the hog2 then rudimentary1 as in the ox and deer2 and finally pass away entirely1 as in the goat4 ,if1 on the other hand1 the four-toed animal is on the line of perissodactyl evolution1 it becomes first a three-toed animal by dropping ,no4 #e4 ,now1 the two side-toes 7,nos4 #b and #d7 shorten up more and more1 and the middle toe increases in size1 until finally1 in the modern horse1 only the greatly enlarged middle toe 7,no4 #c7 remains4 ,we look with wonder and admiration at the danseuse pirouetting on the point of one toe4 ,the horse is performing this feat all the time4 ,yes1 the one toe of a horse has all the three joints like ours4 ,the coffin-bone is the last joint1 and the hoof is the nail4 ,illustration3 a b c d e f g ,equus3 ,quaternary and ,recent4 ,pliohippus3 ,pliocene4 ,protohippus3 ,lower ,pliocene4 ,miohippus3 ,miocene4 ,mesohippus3 ,lower ,miocene4 ,orohippus3 ,eocene4 ,,fig4 #be4--;,diagram illustrating gradual changes in the horse family4 ,throughout a is fore-foot2 b1 hind-foot2 c1 fore-arm2 d1 shank2 e1 molar on side-view2 f and g1 grinding surface of upper and lower molars 7after ,marsh74 ,genesis of the ,horse4--,every step of this process on the perissodactyl line may be traced in the history of the genesis of the horse4 ,the beautiful form and structure of this animal were not made at once1 but by a slow process of integration of small changes from generation to generation1 and from epoch to epoch of the earth's history4 ,the horse 7as in fact did all ungulates7 came from a five-toed plantigrade ancestor1 but we are not able to trace the direct line of genesis quite so far4 ,the earliest stage that we can trace with certainty1 in this line of descent1 is found in the eohippus of ,marsh4 ,this was a small animal1 no bigger than a fox1 with three toes behind and four serviceable toes in front1 with an additional fifth palm-bone 7splint71 and perhaps a rudimentary fifth toe like a dew-claw4 ,this was in early ,eocene times4 ,then1 in later ,eocene1 came the orohippus1 which differs from the last chiefly in the disappearance of the rudimentary fifth toe and splint4 7,see ,fig4 #be47 ,next1 in the ,miocene1 came the mesohippus and miohippus4 ,these were larger animals 7about the size of a sheep71 and had three serviceable toes all around2 but in the former the rudiment of a fourth splint in the fore-limb yet remained4 ,then1 in the ,miocene1 came the protohippus and pliohippus4 ,these were still larger animals1 being about the size of an ass4 ,in the former the two side-toes were shortening up and the middle toe becoming larger4 ,in the latter the two side-toes have become splints4 ,lastly1 only in the ,quaternary comes the genus ,equus1 or true horse4 ,the size of the animal is become greater1 the middle toe stronger1 the side-splints smaller2 but in the side-splints of the modern horse we have still remaining the evidence of its three-toed ancestor4 ,similar gradual changes may be traced in the two leg-bones1 which have gradually consolidated into one2 in the teeth1 which have become progressively longer and more complex in structure1 and therefore a better grinder2 in the position of the heel and wrist1 which have become higher above-ground2 in the general form1 which has become more graceful and agile2 and1 lastly1 in the brain1 which has become progressively larger and more complex in its convolutions--to give greater battery-power1 to make a more powerful dynamo--to work the improved skeletal machine4 ,see1 then1 how long it has taken ,nature to produce that beautiful finished article we call the horse6 99 99 99 99 99 ,we have taken only limbs as examples of what is true of the whole skeleton4 ,to the superficial observer the bodies of animals of different classes seem to differ fundamentally in plan--to be entirely different machines1 made each for its own purposes1 at once1 out of hand4 ,extensive comparison1 on the contrary1 shows them to be the same1 although the essential identity is obscured by adaptive modifications4 ,the simplest1 in fact the only scientific1 explanation of the phenomena of vertebrate structure is the idea of a primal vertebrate1 modified more and more through successive generations by the necessities of different modes of life4 ,see1 then1 in conclusion1 the difference between man's mode of working and ,nature's4 ,a man having made a steam-engine1 and desiring to use it for a different purpose from that for which it was first designed and used1 will nearly always be compelled to add new parts not contemplated in the original machine4 ,nature rarely makes new parts--never1 if she can avoid it--but1 on the contrary1 adapts an old part to the new function4 ,it is as if ,nature were not free to use any and every device to accomplish her end1 but were conditioned by her own plans of structure2 as1 indeed1 she must be according to the derivation theory4 ,for example3 ,in early ,devonian times fishes were the only representatives of the vertebrate type of structure4 ,the vertebrate machine was then a swimming-machine4 ,in the course of time1 when all was ready and conditions were favorable1 reptiles were introduced4 ,here1 then1 is a new function--that of locomotion on land4 ,we want a walking-machine4 ,shall we have a new organ for this new function8 ,no3 the old swimming-organ is modified so as to adapt it for walking4 ,time went on1 until the middle ,jurassic1 and birds were introduced4 ,here is a new and wonderful function1 that of flying in the air4 ,we want a flying-machine4 ,we know how man would have done this2 for we have the result of his imagination in angels of ,christian art and griffins of ,greek mythology4 ,he would have added wings to already existing parts1 and this would have necessitated the alteration of the whole plan of structure1 both skeletal and muscular4 ,nature only modifies the fore-limbs for this new purpose4 ,if we must have wings1 we must sacrifice fore-legs4 ,we can not have both without violating the laws of morphology4 ,finally1 ages again passed1 and1 when time was fully ripe1 man was introduced4 ,now we want some part to perform a new and still more wonderful function4 ,we want a hand1 the willing and efficient servant of a rational mind4 ,we know1 again1 how man would have done this1 for we have the result in the centaurs of ,greek mythology1 in which man's chest1 and arms1 and head are added to the body of a quadruped4 ,but natural laws must not be violated1 even for man4 ,if we want hands1 we must sacrifice feet4 ,again1 therefore1 the fore-limbs are modified for this new and exquisite function4 ,thus1 in the fin of a fish1 the fore-paw of a reptile or a mammal1 the wing of a bird1 and the arm and hand of a man1 we have the same part1 variously modified for many purposes4 ,many other illustrations might be taken from the skeleton and from other systems1 especially the muscular and nervous4 ,but in the muscular system the modifications have been so extreme that homology is much more difficult to trace1 and therefore requires more extensive knowledge than we yet possess1 and more extended comparison than has yet been attempted4 ,it has been traced with some success through mammals1 and probably will be through air-breathing vertebrates--i4 e41 also through birds1 reptiles1 and amphibians2 but to trace it through fishes seems almost hopeless4 ,in the case of the nervous system1 and especially of the brain1 it is again distinct2 but this had better be taken up under another head1 viz41 proofs from ontogeny1 ,chapter ,,vi4 ,in the visceral organs homology is very plain1 in fact too plain4 ,there is not modification enough in most cases even to obscure it1 because function is the same in all animals4 ,these organs do not1 therefore1 furnish good illustrations of that essential identity in the midst of adaptive modification which constitutes the argument for the derivative origin of structure4 ,it is the organs of animal life that show this most perfectly1 because it is these that take hold on the environment and are modified by it4 ,there are1 however1 a few striking illustrations to be found among the visceral organs1 especially the blood-system4 ,this1 however1 had better also be deferred to the chapter on ontogeny4 ,,chapter ,,vi4 ,,homologies ,,of ,,the ,,articulate ,,skeleton4 ,we have taken the vertebrate skeleton first1 only because this department is most familiar4 ,but in reality1 the most beautiful illustrations of essential identity of structure in the midst of infinite diversity of adaptive modification for different functions and habits of life1 and therefore of common origin from a primal form1 are found in the department of articulates4 ,i use the old ,cuvierian department articulata1 rather than the more modern arthropods1 because the former includes worms also4 ,now1 whether worms should be thus included with arthropods1 or deserve a whole department to themselves it matters not for our purposes4 ,it is generally admitted that arthropods probably descended from marine worms4 ,they all have the same general plan of skeletal structure4 ,it will suit my purpose1 therefore1 to regard worms as the lowest form of jointed animals4 ,here1 then1 we have an entirely different plan of structure--a different style of architecture and different mechanical principles of machinery4 ,instead of a skeleton within and muscles acting on the outside1 we have the skeleton on the outside1 and muscles acting from within4 ,instead of two cavities1 a neural and visceral1 the skeleton forms but one cavity1 in which all organs are inclosed and protected4 ,instead of finding the nerve-axis on the dorsal aspect of the body1 we find it on the ventral aspect4 ,illustration3 ,,fig4 #bf4--;,diagram section across an arthropod1 showing the inclosing skeleton-ring and a pair of jointed appendages1 n1 nervous center2 v1 viscera2 b1 blood system4 ,take any articulate animal1 for example1 a shrimp1 a centiped1 or a beetle4 ,cut it across the body1 and look at the end 7,fig4 #bf74 ,we see a ring of bone 7chitin7 inclosing all the organs 7nervous system n1 blood system b1 and visceral system v71 and a pair of jointed appendages1 perhaps legs1 on each side4 ,now imagine these parts repeated in a linear series4 ,the rings repeated make a hollow1 jointed tube or barrel1 the appendages repeated make a continuous row of appendages on each side4 ,now this is exactly what we actually find4 ,the whole articulate skeleton is ideally made up of a series of such repeated rings and appendages1 modified according to the position in the series1 and the uses to which they are put4 ,and then the whole articulate department is made up of such articulate animals again modified according to place in the scale of articulates4 ,the modification in the lower forms is slight1 and therefore the identity of the repeated parts is obvious2 but as we go up the scale1 and the number and complexity of the functions increase1 the adaptive modification becomes greater and greater1 until finally it so obscures the essential identity1 that it requires the most extensive comparison in the taxonomic series and in the ontogenic series1 to pick up the intermediate links and establish the fact of common origin4 ,in a word1 whether they so originated or not1 it is certain that the structure of articulate animals is exactly such as would be the case if all these animals were genetically connected1 and came originally from a primal form something like one of the lower crustaceans1 or1 perhaps1 a marine worm4 ,illustration3 ,,fig4 #bg4--,shrimp 7,palmonetes vulgaris74 ,illustration3 ,,fig4 #bh4--;,external anatomy of the lobster 7after ,kingsley74 ,it will be best to take an example from about the middle of the scale1 where the two elements1 viz41 essential identity and adaptive modification1 are somewhat evenly balanced1 and both traceable with ease and certainty4 ,take1 then1 a cray-fish1 a lobster1 or a shrimp4 ,this animal 7,fig4 #bg7 has twenty or twenty-one rings and pairs of jointed appendages4 ,the rings are some of them diminished1 some of them increased in size4 ,sometimes several are consolidated2 sometimes several are partially or wholly aborted4 ,the appendages are modified in shape and size1 according to their position1 so as to make them swimming-appendages 7swimmerets71 walking-appendages 7legs71 eating-appendages 7jaws71 and sense-appendages 7antenn74 ,for example1 in the abdominal region1 or so-called tail1 we have seven segments1 all being perfect movable rings1 each with its pair of jointed appendages1 except the last1 or telson4 ,the appendages of the first ring 7,fig4 #bh1 ,b7 are specially modified in the male as organs of copulation 7,b74 ,the next four pairs are modified for swimmerets 7,d7 and for use as holders of the eggs in the female4 ,the appendages of the sixth ring 7,g7 are broad and paddle-shaped1 and1 together with the telson or seventh ring 7,h71 form the powerful terminal swimmer4 ,going1 now1 to the cephalo-thorax3 in this either a large number of segments 7thirteen or fourteen7 are consolidated above to form the upper shell or carapace2 or else1 as is more probable1 two or three of the anterior segments have enlarged and grown backward over1 and at the expense of the others1 to form this shell4 ,at any rate1 it is certain that the carapace is formed of the dorsal portions of a number of segments consolidated together4 ,below1 however1 the segments are all distinct1 and have each its own pair of appendages4 ,for example1 going forward in this region1 the five next pairs of appendages are greatly enlarged and very strong1 and serve the purpose of locomotion4 ,they are walking-appendages4 ,the next two or three pairs are smaller and somewhat modified1 but not so much as to obscure their essential similarity to legs4 ,like legs1 they are many-jointed1 and like legs1 too1 they have gills attached to them4 ,they are called maxillipeds1 or jaw-feet4 ,they are used like hands to gather food and carry it to the mouth4 ,they are gathering-appendages4 ,then follow three or four pairs still more modified1 and used for mastication4 ,they are called maxill and mandibles4 ,they are eating-appendages4 ,then follow two pairs1 long1 many-jointed1 with the same kind of curious hinge-joints1 which we have in the legs1 undoubtedly homologous with all the others1 but used for an entirely different purpose1 and specially modified for that purpose4 ,they are the antenn4 ,they are delicate organs of touch and of hearing1 for the ear is situated in the basal joint of the anterior pair4 ,last of all1 there is still another pair1 jointed and movable1 on the ends of which are situated the eyes4 ,these last three1 therefore1 are sense-appendages4 ,some writers make this last pair special organs1 not homologous with appendages4 ,illustration3 ,,fig4 #bi4--;,appendages of a prawn 7after ,cuvier74 ,illustration3 ,,fig4 #cj4--;,appendages of ,nebalia4 ,for the sake of greater distinctness1 we give the whole series of these appendages in one of the higher forms1 viz41 the prawn 7,palemon1 ,fig4 #bi1 and in one of the lower forms1 ,nebalia1 ,fig4 #cj74 ,illustration3 ,,fig4 #ca4--,vibilia1 an amphibod crustacean 7after ,milne ,edwards74 ,that these are really homologous parts is further shown by the fact that in the case of other crustaceans1 such as limulus1 the same appendages1 i4 e41 the appendages of the same body segments1 which in the cases before mentioned are used as feet1 become swimmers1 while the appendages corresponding to jaw-feet become walkers2 and even what corresponds to antenn or sense-appendages1 may1 as in branchippus1 become powerful claspers4 ,finally1 in all the lowest crustaceans1 the identity is evident1 because all the segments and their appendages are much alike in form and function 7,fig4 #ca74 ,illustration3 ,,fig4 #cb4--,lithobius forcipatus 7after ,carpenter74 ,we have taken examples from near the middle of the articulate scale1 because1 as already stated1 both the essential identity and the adaptive modifications are easily traced4 ,if we go downward in the scale1 the structure becomes more and more generalized1 and the rings and appendages become more and more alike 7,fig4 #ca71 until in the most generalized forms we have only a series of similar rings1 with similar pairs of appendages1 except some necessary modifications to form the head and tail4 ,this is well shown in the centiped 7,fig4 #cb71 and still better in marine worms 7,fig4 #cc74 ,in some marine worms the slight modification to form the head takes place under our very eyes4 ,these often multiply by dividing themselves into two4 ,when they do so1 they make a new head and new tail by slight modification of segments and appendages 7,fig4 #cc74 ,illustration3 ,,fig4 #cc4--,syllis prolifera4 ,if1 on the other hand1 we go up the scale1 we find adaptive modifications obscuring more and more the simple and obvious identity of parts1 until finally the identity can not be recognized without extensive comparison in the taxonomic series and study of embryonic conditions4 ,in crabs--which is a higher form than cray-fish--the tail or abdomen seems to be wanting1 but is only very small and bent under the body and thus concealed4 ,in all essential respects the structure is precisely like the cray-fish4 ,in fact1 in the embryo1 we trace the one form into the other2 for the crab is at first a long-tailed crustacean 7,fig4 #cd74 ,illustration3 ,,fig4 #cd4--;,development of ,carcinus mnas4 ,a1 zoa stage2 ,b1 megalopa stage2 ,c1 final state 7after ,couch74 ,insects are the highest form of articulates4 ,in these1 therefore1 we find the modification is still greater than in crustaceans1 though even here the ring-and-appendage structure is plain enough in most cases4 ,one of the best evidences of high grade among animals is the gathering of the segments into distinct groups1 and especially the distinctness of the head as one of these groups4 ,in worms and lower crustaceans there is no grouping at all1 the skeleton being a continuous series of joints1 only slightly modified at the anterior and posterior extremities4 ,in the higher crustacea1 and in spiders and scorpions1 they are grouped into two regions1 viz41 cephalo-thorax and abdomen4 ,in insects they are grouped into three very distinct regions--head1 thorax1 and abdomen4 ,in insects1 therefore1 we find for the first time the head distinctly separated from the rest of the body4 ,this is an evidence of high grade1 because it shows the dominance of head-functions4 ,illustration3 ,,fig4 #ce4--;,external anatomy of ,caloptenus spretus1 the head and thorax disjointed2 up1 uropatagium2 f1 furcula2 c1 cercus 7drawn by ,j4 ,t4 ,kingsley74 ,the insect1 such1 for example1 as a grasshopper1 consists of seventeen or eighteen segments 7,fig4 #ce74 ,of these1 four belong to the head1 three to the thorax1 and about ten to the abdomen4 ,those of the abdomen are all separated and movable2 those of the thorax and head are more or less consolidated4 ,the appendages of the head-segments become antenn and jaw-parts1 i4 e41 mandibles--maxill and labium2 the appendages of the thorac-segments become legs 7the wings are not homologous with appendages71 while those of the abdomen are aborted4 ,the steps of the gradual consolidation on the one hand1 and the abortion on the other1 may be traced in the embryo or larva--i4 e41 in the caterpillar or the grub of a bee or a beetle4 ,in the caterpillar1 for example1 there is no grouping into three regions1 there is no consolidation1 and all the segments have appendages4 ,again1 the almost infinite variety in the mouth-parts among insects1 brought about by adaptive modifications for biting1 for piercing1 and for sucking1 and yet the essential identity of all to the more simple and generalized structure of the grasshopper1 is an admirable illustration of the same principle4 ,but to dwell upon these minor points would carry us too far4 ,illustration of the ,law of ,differentiation4--,we have here1 in the modifications of segments and appendages of articulates1 an admirable illustration of the most fundamental law of evolution1 viz41 the law of differentiation4 ,as we have already seen 7page #ba71 perhaps the most beautiful and certainly the most fundamental illustration of this law is found in the development of cell-structure4 ,commencing in the lowest animals1 and in the earliest embryonic stages of the higher animals1 from a condition in which all are alike1 the cells as we go upward quickly diverge into different forms to produce different tissues and perform different functions4 ,here1 then1 we have a perfect example of essential identity and adaptive modification4 ,it is the very best type of differentiation4 ,so also skeletal segments1 commencing1 in the lowest articulates and in earliest embryonic stages of the higher1 all alike1 as we go upward in either series1 begin immediately to diverge in various directions 7divergent variation71 taking different forms to subserve different uses4 ,here1 again1 therefore1 is an illustration of the law of differentiation4 ,lastly1 in the articulate department1 commencing with the lowest forms and earliest embryonic conditions1 and we may add earliest geological times1 and going up either series from generalized forms very much alike1 the individuals are gradually differentiated into many special forms1 in order to adapt them to the diversified modes of life actually found in nature4 ,thus cells1 segments1 individuals1 are all alike affected by this most fundamental law4 ,we have taken our illustrations from only the two departments of vertebrata and articulata1 because these are the most familiar to the reader1 and also have been most carefully studied4 ,we have shown that the general structure of all vertebrates is precisely what it would be if they all had come from one primal vertebrate form1 and that of all articulates what it would be if all had come from one primal articulate form4 ,the only natural explanation1 and1 therefore1 the only scientific explanation of this1 is that they were really thus derived4 ,the same kind of evidence may be drawn from the study of other departments1 but to pursue the subject any further in this direction would carry us beyond the limits which we have assigned4 ,we desire only to explain the nature1 not to give all1 of the evidence4 ,the examples given will be sufficient for the purposes of illustration4 ,the whole proof is nothing less than the whole science of comparative anatomy4 ,vertebrates1 then1 were derived from a primal vertebrate1 articulates from a primal articulate1 and so for other departments4 ,but whence were these primals derived8 ,are there any intermediate links between1 any deeply concealed common plan of structure underlying these primary groups1 showing a common origin8 ,it must be confessed that1 in their mature condition1 there seems to be but little evidence of such4 ,these primary groups seem to be built on different plans1 to be fundamentally of different styles of architecture4 ,therefore ,darwin1 in the true spirit of inductive caution--that true scientific spirit which keeps strictly within the limits of evidence--commences with four or five distinct primal kinds1 from which by divergent variation all animals were descended4 ,nevertheless1 the truly scientific biologist must ever strongly incline to believe that these also came from some primal animal1 and even that both animals and plants were derived from some primal form of living thing2 that as1 in the taxonomic series1 the animal and vegetal kingdoms in their lowest forms merge undistinguishably into one another2 as in the ontogenic series the animal and plant germ are one1 so also in the phylogenic series the earliest organisms were simply living things1 but not distinctively animal nor vegetal4 ,science1 therefore1 whose mission is to trace origins as far back as possible1 must ever strive to find connecting links between the primary groups4 ,some such have been supposed to have been discovered4 ,some find the origin of vertebrates among the molluscoids 7ascidians72 some find the origins of both vertebrates and articulates among marine worms 7annelids74 ,this point is still too doubtful to be dwelt upon here4 ,it may be that we seek in vain for such connecting links among existing forms4 ,it may well be that the point of separation of these great primary groups 7unless we except vertebrates7 was far lower even than these low forms4 ,both phylogeny and ontogeny seem to indicate this4 ,in the earliest fauna known1 the primordial 7for if there was life in the archan it was not yet differentiated into a fauna71 all the great departments1 except the vertebrates1 seem to have been represented4 ,in embryonic development1 too1 the point of connection or even of similarity1 between the great departments1 is found1 as we shall see hereafter1 only in the earliest stages--i4 e41 lower down than any but the lowest existing forms1 viz41 the protozoa4 ,,chapter ,,vii4 ,,proofs ,,from ,,embryology1 ,,or ,,comparison ,,in ,,the ,,ontogenic ,,series4 ,it is a curious and most significant fact that the successive stages of the development of the individual in the higher forms of any group 7ontogenic series7 resemble the stages of increasing complexity of differentiated structure in ascending the animal scale in that group 7taxonomic series71 and especially the forms and structure of animals of that group in successive geological epochs 7phylogenic series74 ,in other words1 the individual higher animal in embryonic development passes through temporary stages1 which are similar in many respects to permanent or mature conditions in some of the lower forms in the same group4 ,to give one example for the sake of clearness3 ,the frog1 in its early stages of embryonic development1 is essentially a fish1 and if it stopped at this stage would be so called and classed4 ,but it does not stop2 for this is a temporary stage1 not a permanent condition4 ,it passes through the fish stage and through several other temporary stages1 which we shall explain hereafter1 and onward to the highest condition attained by amphibians4 ,now1 if we could trace perfectly the successive forms of amphibians1 back through the geological epochs to their origin in the ,carboniferous1 the resemblance of this series to the stages of the development of a frog would doubtless be still closer4 ,surely this fact1 if it be a fact1 is wholly inexplicable except by the theory of derivation or evolution4 ,the embryo of a higher animal of any group passes now through stages represented by lower forms1 because in its evolution 7phylogeny7 its ancestors did actually have these forms4 ,from this point of view the ontogenic series 7individual history7 is a brief recapitulation1 as it were1 from memory1 of the main points of the philogenic series1 or family history4 ,we say brief recapitulation of the main points1 because many minor points are dropped out4 ,even some main points of the earliest stages of the family history may be dropped out of this sort of inherited memory4 ,this resemblance between the three series must not1 however1 be exaggerated4 ,not only are many steps of phylogeny1 especially in its early stages1 dropped out in the ontogeny1 but1 of course1 many adaptive modifications for the peculiar conditions of embryonic life are added4 ,but it is remarkable how even these--for example the umbilical cord and placenta of the mammalian embryo--are often only modifications of egg-organs of lower animals1 and not wholly new additions4 ,it is the similarity in spite of adaptive modifications that shows the family history4 ,we will now illustrate by a few striking examples4 ,we can not do better than to take1 again1 as our first example1 the development of tailless amphibians1 and dwell a little more upon it3 #a4 ,ontogeny of ,tailless ,amphibians4--,it is well known that the embryo or larva of a frog or toad1 when first hatched1 is a legless1 tail-swimming1 water-breathing1 gill-breathing animal4 ,it is essentially a fish1 and would be so classed if it remained in this condition4 ,the fish retains permanently this form1 but the frog passes on4 ,next1 it forms first one pair and then another pair of legs2 and meanwhile it begins to breathe also by lungs4 ,at this stage it breathes equally by lungs and by gills2 i4 e41 both air and water4 ,now1 the lower forms of amphibians1 such as siredon1 menobranchus1 siren1 etc41 retain permanently this form1 and are therefore called perennibranchs1 but the frog still passes on4 ,then the gills gradually dry up as the lungs develop1 and they now breathe wholly by lungs1 but still retain the tail4 ,now this is the permanent1 mature condition of many amphibians1 such as the triton1 the salamander1 etc41 which are therefore called caducibranchs1 but the frog still passes on4 ,finally1 it loses the tail1 or rather its tail is absorbed and its material used in further development1 and it becomes a perfect frog1 the highest order 7anoura7 of this class4 ,thus1 then1 in ontogeny the fish goes no further than the fish stages4 ,the perennibranch passes through the fish stage to the perennibranch amphibian4 ,the caducibranch takes first the fish-form1 then the perennibranch-form1 and finally the caducibranch-form1 but goes no further4 ,last1 the anoura takes first the fish-form1 then that of the perennibranch1 then that of the caducibranch1 and finally becomes anoura4 ,this is shown in the diagram1 which must be read upward1 line by line4 ,illustration3 ,,fish4 ,,perennibranch4 ,,caducibranch4 ,,anoura4 ,,fish4 ,,perennibranch4 ,,caducibranch4-------- ,,fish4 ,,perennibranch----------- ,,fish4------------ ,diagram showing the stages of development of amphibians4 7,to be read upward47 ,now1 this is undoubtedly the order of succession of forms in geological times--i4 e41 in the phylogenic series4 ,this series is indicated by the arrows in the diagram4 ,fishes first appeared in the ,devonian and ,upper ,silurian in very reptilian or rather amphibian forms4 ,then in the ,carboniferous1 fishes still continuing1 there appeared the lowest--i4 e41 most fish-like--forms of amphibians4 ,these were undoubtedly perennibranchs4 ,in the ,permian and ,triassic higher forms appeared1 which were certainly caducibranch4 ,finally1 only in the ,tertiary1 so far as we yet know1 do the highest form 7anoura7 appear4 ,the general similarity of the three series is complete4 ,if we read the diagram horizontally1 we have the ontogenic series2 if diagonally with the arrows1 we have both the taxonomic and the phylogenic series4 #b4 ,aortic ,arches4--,but some will1 perhaps1 say that these stages in the ontogeny are only examples of adaptive modifications--like modifications for like conditions of life--and had better be accounted for in this way1 without reference to family history4 ,we will1 therefore1 take another example1 which can not be thus accounted for--an example in which there is no possible use now for the peculiar form or structure which we find4 ,for this purpose we take the case of the course of circulation in vertebrates4 ,illustration3 ,,fig4 #cf4--,showing heart and outgoing blood-vessels of a lizard 7after ,owen74 ,the arrows show the course of the blood4 ,illustration3 ,,fig4 #cg4--;,a1 heart and gill-arches of a fish2 ,b1 one arch1 with fringe 7after ,owen72 ,h1 the heart4 ,if one examines the large vessels going out from the heart of a lizard1 he will find six aortic arches--i4 e41 three on each side4 ,these all unite below to form the one descending abdominal aorta4 ,this is shown in the accompanying figure 7,fig4 #cf71 in which a a a and b b b are the six arches4 ,now1 there is no conceivable use in having so many aortic arches4 ,we know this1 because there is but one in birds and mammals1 and the circulation is as effective1 nay1 much more effective in these than in reptiles4 ,the explanation of this anomaly is revealed at once as soon as we examine the circulation of a fish1 which is shown in the accompanying figure 7,fig4 #cg74 ,the multiplication of the aortic arches is here1 of course1 necessary1 for they are the gill-arches4 ,the whole of the blood passes through these arches1 to be arated in the gill-fringes4 ,the use of this peculiar structure is here obvious enough4 ,if a lizard were ever a fish1 and afterward turned into a lizard1 changing its gill-respiration for lung-respiration1 then1 of course1 the useless gill-arches would remain to tell the story4 ,now1 although a lizard never was a fish1 in its individual history or ontogeny1 it was a fish in its family history or phylogeny1 and therefore it yet retains1 by heredity1 this curious and useless structure as evidence of its ancestry4 ,illustration3 ,,fig4 #ch4 ,illustration3 ,,fig4 #ci4 ,,figs4 #ch1 #ci4--;,diagrams showing the change of the course of blood in the development of a frog4 #ch4 ,the tadpole stage4 #ci4 ,the mature condition4 ,h1 heart2 ,g ,g ,g1 external gills2 g g g1 internal gills2 c c1 connecting branches in the tadpole2 p p1 pulmonary branches4 ,that this is the true explanation is demonstrated by the fact that in amphibians this very change actually takes place before our eyes in the individual history4 ,we have already seen that the individual frog1 in its tadpole state1 is a gill-breather4 ,it has therefore its gill-arches 7,fig4 #ch71 three on each side1 like a fish1 and for the same reason1 viz41 the aration of the blood4 ,but when its gills dry up and lung-respiration is established1 its now useless gill-arches still remain as aortic arches1 to attest their previous condition 7,fig4 #ci74 ,now1 the lizard undoubtedly came from an air-breathing1 tailed amphibian1 and therefore inherited this form of arterial distribution4 ,in both lizard and amphibian the ultimate cause is an origin from fishes1 in which such arches are obviously necessary4 ,the diagrams1 ,figs4 #ch and #ci1 are illustrations somewhat idealized1 showing the manner in which the change actually takes place in air-breathing amphibians4 ,fig4 #ch represents the tadpole stage1 and ,fig4 #ci the mature condition4 ,in the former the gills are mostly external1 ,g ,g1 etc41 but also internal1 g g1 as in the fish4 ,observe in this condition the small connecting vessels1 c c4 ,when the external gills dry up1 these are enlarged1 and the whole of the blood passes through them1 as shown in ,fig4 #ci4 ,it is seen1 also1 in ,fig4 #ch1 that a small branch1 p1 goes from the lower gill-arches to the yet rudimentary lung1 l4 ,when the gill-fringes have disappeared1 the whole of the blood of the lower arch goes through the now enlarged pulmonary branch to the lungs1 ,l1 now in full activity1 and the remainder of this arch disappears1 as shown by the dotted lines in ,fig4 #ci4 ,the change which actually took place in the family history of the lizard probably differed from the above only in being more simple1 the gills being only internal like the fish4 ,the external gills complicate the process a little in the case of the frog1 but the principle is precisely the same4 ,as already explained 7pages #hb-he71 the large gap between fishes and reptiles1 as regards mode of respiration1 is completely filled both in the taxonomic series--i4 e41 in ganoids1 dipnoi1 and the mature condition of the different orders of amphibians--and in the ontogeny of the higher amphibians4 ,now1 we add that the same is true of the arterial distribution4 ,we have just traced the change in the ontogeny of the frog1 but the steps of the same change are traceable in passing from the typical fish 7teleosts71 through dipnoi and amphibians to reptiles4 ,thus1 again1 the phylogeny1 the taxonomy1 and the ontogeny1 are in complete accord4 ,but the argument for evolution does not stop here4 ,if birds and mammals have come from reptiles1 and therefore from fishes1 we may expect to find some evidences of the same kind still lingering in the great arteries4 ,and such we do find4 ,it is a most curious and significant fact that1 in the early embryonic condition of birds and mammals1 including man himself1 we find on each side of the neck several gill-slits1 each with its gill-arch1 and therefore several aortic arches on each side1 precisely similar to what we have already described4 ,these arches are subsequently1 some of them1 obliterated2 some modified to form the one aortic arch1 and some of them still more modified to form the other great arteries coming from the heart to supply the head and forelimbs4 ,illustration3 ,,fig4 #dj4--;,diagram of mammalian heart4 a1 aorta2 p1 pulmonary artery2 scsc1 subclavium on each side2 cc1 carotids on each side4 ,illustration3 ,,fig4 #da4--;,ideal diagram representing the primitive aortic arches 7after ,rathke74 ,this is so beautiful and convincing an example1 and one so generally unfamiliar1 to even intelligent persons1 not especially acquainted with biology1 that it is best to explain it more fully4 ,in ,fig4 #dj we give a mammalian heart and outgoing vessels1 very slightly modified1 so as to suggest the process of change4 ,in ,fig4 #da we give an ideal diagram representing the primitive aortic arches as they exist in the embryo of mammals1 birds1 and reptiles4 ,it represents1 also1 substantially1 the arches as they exist in the mature condition in the most reptilian fishes 7dipnoi7 and in some sharks1 except that in these the arches are of course furnished with gill-fringes4 ,we will use this figure1 therefore1 to represent both the embryonic condition of air-breathing vertebrates and the mature condition of some fishes4 ,the place of the heart is indicated by the dotted circle4 ,fig4 #cf1 on page #acd1 shows what these arches become in reptiles 7lizard74 ,it is seen that the two upper arches on each side are obliterated1 as indeed they already are in some teleost fishes4 ,fig4 #db shows what they become in birds4 ,the two upper arches are1 of course1 obliterated4 ,the others are all modified1 each in a manner which may be readily understood by comparison with ,fig4 #da4 ,finally1 ,fig4 #dc shows what they become in mammals and in man4 ,in the bird 7,fig4 #db7 the first pair of arches become the two pulmonary arteries as they do also in the lizard4 ,the second pair become on the right side 7left of the diagram7 the aortic arch1 on the left side 7right of the diagram7 the left subclavian1 sc 7the right subclavian1 sc1 is a branch of the aortic arch74 ,the third pair become carotids1 cc1 while the fourth and fifth1 as already said1 are aborted4 ,in the mammal 7,fig4 #dc71 on the left side 7right of the diagram7 the first arch becomes the pulmonary artery1 p4 ,in the ftus the continuation of this arch forms the ductus arteriosus1 which is afterward obliterated1 as shown in the dotted line4 ,the second arch becomes the aortic arch1 the third the left exterior carotid4 ,on the right side 7left of the diagram7 the first arch becomes aborted2 the second1 the right subclavian1 sc 7the left subclavian1 sc1 is a branch of the aortic arch72 and the third1 the right carotid4 ,nos4 #d and #e1 on both sides1 as usual1 are aborted4 ,illustration3 ,,fig4 #db4--,modified for bird4 ,illustration3 ,,fig4 #dc4--,modified for mammal4 ,illustration3 ,,fig4 #dd4--,lancelet 7,amphioxus lanceolatus74 ,magnified two and one-half times4 ,see1 then1 the gradual process of change through the whole vertebrate department4 ,in the lowest of all vertebrates1 if vertebrate it may be called 7for what corresponds to its backbone is an unjointed1 fibrous cord71 the amphioxus or lancelet 7,fig4 #dd71 there are about forty gill-arches on each side4 ,as we rise in the scale of fishes these are reduced in number4 ,in the lamprey1 there are seven2 in the sharks1 usually five2 in ordinary fishes 7teleosts71 there are four or sometimes only three on each side1 the others being aborted4 ,thus far the change is only by diminution of number in accordance with a law universal in biology1 that decrease in the number of identical organs is evidence of advance in the grade of organization1 provided that it be associated with more perfect structure of the organ4 ,the further change is one of adaptive modification4 ,in some reptiles 7lizard7 the three gill-arches on each side all retain the form of aortic arches2 in some reptiles only two retain this form4 ,in birds and mammals only one arch is retained1 in the form of aortic arch1 the others being modified to form the great outgoing vessels of the heart1 or else aborted4 ,it may be well to observe that in birds the one aortic arch turns to the right1 while in mammals it turns to the left4 ,this is positive evidence that mammals could not have come from birds1 nor vice versa4 ,they both came from reptiles1 and1 of the many reptilian arches1 a right one was retained by the bird branch1 and a left one by the mammalian4 ,in all the figures illustrating this subject1 we have left out the great incoming vessels or veins1 because we are not here concerned with them1 they not being transformed gill-arches4 ,last of all1 it may be well to stop a moment to show the cogency of this evidence4 ,if it were a question of the origin of some structure not only useful 7for all structures selected by ,nature must be useful7 but the best imaginable1 like the eye or the ear1 for example2 then1 if we examined only the highest form or the finished article1 there are two ways in which it is possible to explain the adaptive structure4 ,we may either suppose that it was made at once out of hand1 by some intelligent contriver2 or else that it was slowly made by a process of evolution1 becoming more and more perfect by a selection of only the most perfect from generation to generation4 ,but in the case of the six aortic arches of the lizard1 we are shut up to the one explanation only1 viz41 by slow process of evolution4 ,one arch is all that is necessary1 as is plainly shown by the use of only one in the more perfect circulation of birds and mammals4 ,if the thing were done out of hand1 unconditioned by the previous structure in fishes1 to have made six was surely but a bungling piece of work4 ,illustration3 ,,fig4 #de4--;,fish-brain4 ,a1 side view2 ,b1 top view4 ,illustration3 ,,fig4 #df4--,reptile-brain4 ,a1 side view2 ,b1 top view4 ,illustration3 ,,fig4 #dg4--;,bird-brain4 ,a1 side view2 ,b1 top view4 ,illustration3 ,,fig4 #dh4--,mammal-brain4 ,a1 top view2 ,b1 side view4 ,illustration3 ,,fig4 #di4--,man's brain4 ,a1 side view2 ,b1 top view4 #c4 ,vertebrate ,brain4--,another excellent example is the structure of the vertebrate brain4 ,the brain of an average fish is represented in ,fig4 #de4 ,it consists of four or five swellings1 or ganglia1 strung along1 one beyond another4 ,commencing behind1 these are1 first1 the medulla1 m2 then the cerebellum1 cb2 then the optic lobes1 ol2 then the cerebrum and thalamus combined1 cr2 and last1 the olfactive lobes1 of4 ,of these1 it will be observed1 the optic lobe is the largest in the brain of the fish 7,fig4 #de74 ,in the brain of the reptile 7,fig4 #df7 we have the same serial arrangement1 of the same parts1 only that the cerebrum has now become the dominant part instead of the optic lobes4 ,in the average bird 7,fig4 #dg7 the cerebrum has grown so large that it extends backward1 and partly covers the optic lobes4 ,in the lower mammals 7marsupials71 the brain is much the same in this respect1 as in birds--i4 e41 the cerebrum only partly covers the optic lobes1 so that1 looked at from above1 the whole series of ganglia are still visible4 ,but in the average mammal 7,fig4 #dh7 the cerebrum is so enlarged that it covers entirely the optic lobes and encroaches on the cerebellum behind and the olfactive lobes in front4 ,in some monkeys1 indeed1 the cerebellum is nearly or even quite covered4 ,finally1 in man 7,fig4 #di71 the cerebrum has grown so enormously that it covers every other part and completely conceals them from view when the brain is looked at from above4 ,in front it not only covers but has grown far beyond the olfactive lobes2 behind it extends beyond and overhangs the cerebellum2 on the sides it overhangs and covers all4 ,looked at from above1 nothing is seen but this great ganglion4 ,the ideal section 7,fig4 #ej7 represents all these stages diagrammatically in one figure4 ,after what has been said1 the figure will be readily understood4 ,illustration3 ,,fig4 #ej4--;,ideal section showing all the above stages4 ,illustration3 ,,fig4 #ea4--,sub-fish ,stage4 th1 thalamus2 ol1 optic lobe2 m1 medulla4 ,illustration3 ,,fig4 #eb4--;,fish-stage4 of1 olfactive lobe2 cr1 cerebrum2 th1 thalamus2 ol1 optic lobe2 cb1 cerebellum2 m1 medulla4 ,illustration3 ,,fig4 #ec4--,reptile-stage4 ,now1 it is a most remarkable fact that substantially these same stages1 which are permanent conditions in the taxonomic series1 are passed through as transient stages in the embryonic development of the human brain1 and in the order given above4 ,the very early condition of the human brain is represented in ,fig4 #ea4 ,it is evidently nothing more than the intercranial continuation of the spinal cord1 enlarged a little into three swellings or ganglia4 ,these are the early representatives of the medulla1 the optic lobes1 and the thalamus2 which last may be regarded as the basal and most fundamental part of the cerebrum4 ,this stage may be regarded as lower than that of the ordinary fish4 ,i have called it1 therefore1 the sub-fish stage4 ,the cerebellum is a subsequent outgrowth from the medulla1 as is the cerebrum and olfactive lobes from the thalamus4 ,fig4 #eb may be said1 therefore1 to represent fairly the fish-stage4 ,henceforward the principal growth is in the cerebrum and cerebellum1 both of which are subsequent outgrowths of the original simple ganglia1 the medulla1 and the thalamus4 ,the cerebrum especially increases steadily in relative size1 first becoming larger than but not covering the optic lobes 7,fig4 #ec74 ,this represents the reptilian stage4 ,next1 by further growth1 it covers partly the optic lobes 7,fig4 #ed74 ,this may be called the bird-stage4 ,then it covers wholly the optic lobes1 and encroaches on the cerebellum behind and olfactive lobes in front 7,fig4 #ee74 ,this is the mammalian stage4 ,finally1 it covers and overhangs all1 and thus assumes the human stage 7,fig4 #ef74 ,illustration3 ,,fig4 #ed4--;,bird-stage4 of1 olfactive lobe2 cr1 cerebrum2 th1 thalamus2 ol1 optic lobe2 cb1 cerebellum2 m1 medulla4 ,illustration3 ,,fig4 #ee4--,mammalian stage4 ,illustration3 ,,fig4 #ef4--;,human stage4 ,we have spoken thus far only of relative size2 but progressive changes take place also in complexity of structure--i4 e41 in the depth and number of convolutions of the cerebrum and cerebellum4 ,the cerebrums of fish1 of reptile1 bird1 and lower mammals are smooth4 ,about the middle of the mammalian series it begins to be convoluted4 ,these convolutions become deeper and more numerous as we go upward in the scale1 until they reach the highest degree in the human brain4 ,the object of these inequalities is to increase the surface of gray matter--i4 e41 the extent of the force-generating as compared with the force-transmitting part of the brain1 or battery as compared with conducting-wire4 ,now1 in embryonic development the human brain passes also through these stages of increasing complexity of organization4 ,here also the ontogenic is similar to the taxonomic series4 ,now1 why should this peculiar order be observed in the building of the individual brain8 ,we find the answer1 the only conceivable scientific answer to this question1 in the fact that this is the order of the building of the vertebrate brain by evolution throughout geological history4 ,we have already seen that fishes were the only vertebrates living in the ,devonian times4 ,the first form of brain1 therefore1 was that characteristic of that class4 ,then reptiles were introduced2 then birds and marsupials2 then true mammals2 and1 lastly1 man4 ,the different styles of brains characteristic of these classes were1 therefore1 successively made by evolution from earlier and simpler forms4 ,in phylogeny this order was observed because these successive forms were necessary for perfect adaptation to the environment at each step4 ,in taxonomy we find the same order1 because1 as already explained 7page #aa71 every stage of advance in phylogeny is still represented in existing forms4 ,in ontogeny we have still the same order1 because ancestral characteristics are inherited1 and family history recapitulated in the individual history4 ,illustration3 ,,fig4 #eg4--;,a1 brain of extinct ,ichthyornis2 ,b1 modern tern4 ,illustration3 ,,fig4 #eh4--;,a1 brain of ,eocene dinoceras2 ,b1 ,miocene brontothere2 ,c1 modern horse4 ,but not only is this order found in the evolution of the whole vertebrate department1 but something of the same kind is found also in the evolution of each class4 ,the earliest reptiles1 the earliest birds1 and the earliest mammals had smaller and less perfectly organized brains than their nearest congeners of the present day4 ,this is shown in the accompanying figures 7,figs4 #eg and #eh74 ,to carry out one example more perfectly3 ,in the history of the horse family1 in connection with the changes of skeletal structure already described 7page #ajh71 we have also corresponding changes in the size and structure of the brain2 pari passu with the improvement of the mechanism we have also increased engine-power and increased muscular energy and therefore increased activity and grace4 ,the brain of a modern horse1 though not very large1 is remarkable for the complexity of its convolutions4 ,the great energy1 activity1 and nervous excitability of the horse are the result of this structure4 ,cephalization4--,thus1 in going up the phylogenic1 the taxonomic1 or the ontogenic series1 we find a gradual process of development headward1 brainward1 cerebrumward2 or1 more generally1 we might say that in all organic evolution we find an increasing dominance of the higher over the lower1 and of the highest over all4 ,for example1 in the lowest plane of either series we find first the different systems imperfectly or not at all differentiated4 ,then1 as differentiation of these progress1 we find an increased dominance of the highest system--the nervous system2 then in the nervous system1 the increasing dominance of its highest part--the brain2 then in the brain the increasing dominance of its highest ganglion--the cerebrum2 and1 lastly1 in the cerebrum the increasing dominance of its highest substance--the exterior gray matter--as shown by the increasing number and depth of the convolutions4 ,this whole process may be called cephalization4 ,shall the process stop here8 ,when evolution is transferred from the animal to the human plane1 from the physiological to the psychical1 from the involuntary and necessary to the voluntary and free1 shall not the same law hold good8 ,yes6 all social evolution1 all culture1 all education1 whether of the race or the individual1 must follow the same law4 ,all psychical advance is a cephalization--i4 e41 an increasing dominance of the higher over the lower and of the highest over all2 of the mind over the body1 and in the mind of the higher faculties over the lower2 and1 finally1 the subordination of the whole to the highest moral purpose4 ,illustration3 ,,fig4 #ei4--;,homocercal tail-fin4 ,a1 form2 ,b1 structure4 ,illustration3 ,,fig4 #fj4--;,heterocercal or vertebrated tail-fin4 ,a1 form2 ,b1 structure4 #d4 ,fish-,tails4--,still another and last example3 ,it has long been noticed that there are among fishes two styles of tail-fins4 ,these are the even-lobed1 or homocercal 7,fig4 #ei71 and the uneven-lobed1 or heterocercal 7,fig4 #fj74 ,the one is characteristic of ordinary fishes 7teleosts71 the other of sharks and some other orders4 ,in structure the difference is even more fundamental than in form4 ,in the former style the backbone stops abruptly in a series of short1 enlarged joints1 and thence sends off rays to form the tail-fin 7,fig4 #ei1 ,b72 in the latter the backbone runs through the fin to its very point1 growing slenderer by degrees1 and giving off rays above and below from each joint1 but the rays on the lower side are much longer 7,fig4 #fj1 ,b74 ,this style of fin is1 therefore1 vertebrated1 the other non-vertebrated4 ,figs4 #ei and #fj show these two styles in form and structure4 ,but there is still another style found only in the lowest and most generalized forms of fishes4 ,in these the tail-fin is vertebrated and yet symmetrical4 ,this style is shown in ,fig4 #fa1 ,a and ,b4 ,illustration3 ,,fig4 #fa4--,vertebrated but symmetrical fin4 ,a1 form2 ,b1 structure4 ,now1 in the development of a teleost fish 7,fig4 #eh71 as has been shown by ,alexander ,agassiz1#bd the tail-fin is first like ,fig4 #fa2 then becomes heterocercal1 like ,fig4 #fj2 and1 finally1 becomes homocercal like ,fig4 #ei4 ,why so8 ,not because there is any special advantage in this succession of forms2 for the changes take place either in the egg or else in very early embryonic states4 ,the answer is found in the fact that this is the order of change in the phylogenic series4 ,the earliest fish-tails were either like ,fig4 #fa or ,fig4 #fj2 never like ,fig4 #ei4 ,the earliest of all were almost certainly like ,fig4 #fa2 then they became like ,fig4 #fj2 and1 finally1 only much later in geological history 7,jurassic or ,cretaceous71 they became like ,fig4 #ei4 ,this order of change is still retained in the embryonic development of the last introduced and most specialized order of existing fishes4 ,the family history is repeated in the individual history4 ,illustration3 ,,fig4 #fb4--,tail of the ,archopteryx4 ,illustration3 ,,fig4 #fc4--,tail of a modern bird4 ,similar changes have taken place in the form and structure of birds' tails4 ,the earliest bird known--the ,jurassic ,archopteryx--had a long reptilian tail of twenty-one joints1 each joint bearing a feather on each side1 right and left 7,fig4 #fb74 ,in the typical modern bird1 on the contrary1 the tail-joints are diminished in number1 shortened up1 and enlarged1 and give out long feathers1 fan-like1 to form the so-called tail 7,fig4 #fc74 ,the ,archopteryx' tail is vertebrated1 the typical bird's non-vertebrated4 ,this shortening up of the tail did not take place at once1 but gradually4 ,the ,cretaceous birds1 intermediate in time1 had tails intermediate in structure4 ,the ,hesperornis of ,marsh had twelve joints4 ,at first--in ,jurassic--the tail is fully a half of the whole vertebral column4 ,it then gradually shortens up until it becomes the aborted organ of typical modern birds4 ,now1 in embryonic development1 the tail of the modern typical bird passes through all these stages4 ,at first the tail is nearly one half the whole vertebral column2 then1 as development goes on1 while the rest of the body grows1 the growth of the tail stops1 and thus finally becomes the aborted organ we now find4 ,the ontogeny still passes through the stages of the phylogeny4 ,the same is true of all tailless animals4 ,the frog is tailed in the larval condition1 because its ancestors were tailed amphibians4 ,even man himself is endowed with a much more considerable tail1 viz41 eight or nine joints1 in his early embryonic condition4#be ,we have taken all our examples from vertebrates1 but quite as many and as good examples might be found among articulates4 ,insects1 in the larval state1 are worm-like in form4 ,hence it is probable that the earliest progenitors of this class were worm-like4 ,again1 some insects have aquatic larv4 ,the progenitors of these--in fact1 of all insects--were probably aquatic4 ,crabs1 in a larval condition1 are long-tailed1 and we know that the long-tailed crustaceans 7,macrourans7 preceded the short-tailed 7,brachyourans74 ,water-breathing animals preceded air-breathers2 the same is true in the ontogeny of the frog1 of many insects1 and1 we might add1 even of mammals4 ,for the breathing of the ftus in utero is essentially by exposure of ftal blood to the oxygenated blood of the mother in a sort of gill-fringes 7placental tufts74 ,but why should we multiply examples8 ,the whole of embryology1 in every department1 is made up of examples of the same law4 ,illustration of the ,differentiation of the ,whole ,animal ,kingdom4--,finally1 the law of differentiation in the evolution of the whole animal kingdom may be well illustrated by means of the different directions taken in the development of the eggs of all the various kinds of animals4 ,suppose1 then1 we have one thousand eggs1 representing all the different departments1 classes1 orders1 families1 etc41 of animals4 ,many of these may doubtless be identified by form or size1 or some other superficial character1 as the eggs of this or that animal1 but structurally they are all alike4 ,at first1 i4 e41 as germ-cells1 they all represent the earliest condition of life on the earth1 and the lowest forms of life now4 ,if we now watch their development1 we find that some remain in this first condition without further change4 ,these we set aside4 ,they are ,protozoa4 ,the remainder continue to develop1 but at first it would be impossible to say to which of the several departments or primary groups they each belonged4 ,then1 by cell-multiplication1 the original single cell becomes a cell-aggregate4 ,it may be compared now to a compound protozoan1 such as ,foraminifera4 ,the cell-aggregate then differentiates into layers1 and forms1 in fact1 a two-layered sac called a gastrula4 ,this is the structure of some of the lowest clenterates1 such as the hydra4 ,thus far all seem to go together4 ,but now1 for the first time1 the primary groups are declared4 ,if it be a vertebrate1 for example1 the most fundamental characters--the cerebro-spinal axis1 the vertebral column1 and the double cavity1 neural and visceral1 are outlined4 ,suppose1 now1 we set aside all other departments1 and fix our attention on the vertebrates4 ,at first we could not tell which were mammals1 birds1 reptiles1 or fishes2 but after a while the classes are declared4 ,we now set aside all other classes and watch the mammals4 ,after a while the order declares itself4 ,we select the ungulates4 ,then the family is declared1 say the ,equid2 then the genus1 ,equus2 and1 lastly1 the species1 ,caballus4#bf ,the same would be true if we followed any other line of development1 whether in vertebrates or in any other department4 ,observe1 then1 that1 in following any one line as we have done1 there is an increasing specialization1 and1 if we followed all the lines1 an increasing differentiation1 like the branching and rebranching of a tree4 ,now1 this is the type and illustration of what took place in the development of the animal kingdom4 ,we conclude that the animal kingdom appeared first as ,protozoa1 then as living cell-aggregates or compound protozoans1 then as gastrula or two-layered sacs with oral opening4 ,then the great primary departments1 unless we except the vertebrates1 commenced to separate4 ,this took place before the primordial period2 for in the primordial fauna we have all the departments1 except vertebrates1 already declared4 ,this completely explains why it is that we are able to trace homology only within the limits of each primary group4 ,but the question has doubtless already occurred to the thoughtful reader1 8,why should the steps of the phylogeny be repeated in the ontogeny80 ,the general answer is doubtless to be found in the law of heredity--that wonderful law1 so characteristic of living things4 ,we have compared it to a brief recapitulation from memory--the minor points1 especially if they be also early1 dropping out4 ,but can we not explain it further8 ,it is probable that we find a more special explanation in 8the law of acceleration10 first brought forward by ,prof4 ,cope4 ,by the law of heredity each generation repeats the form and structure of the previous1 and in the order in which they successively appeared4 ,but there is a tendency for each successively-appearing character to appear a little earlier in each successive generation2 and by this means time is left over for the introduction of still higher new characters4 ,thus1 characters which were once adult are pushed back to the young1 and then still back to the embryo1 and thus place and time are made for each generation to push on still higher4 ,the law of acceleration is a sort of young-,americanism in the animal kingdom4 ,if our boys acquire knowledge and character similar to that of adults of a few generations back1 they will have time while still young and plastic to press forward to still higher planes4 ,proofs from ,rudimentary and ,useless ,organs4--,these have to a large extent been anticipated under previous heads4 ,the tails of birds and the gill-arches of reptiles are rudimentary4 ,the finger-bones of a whale's paddle or a turtle's flipper may be regarded as useless1 at least so far as the exact number of constituent pieces is concerned2 for an extended surface1 without visible joints or separate fingers1 is all that is seen1 and apparently all that is required4 ,the splint-bones of a horse's foot or the dew-claws of a dog's foot are certainly useless4 ,we have already1 in speaking of modifications of structure and of embryonic conditions1 given many examples of this kind1 but it may be well to add some striking examples with this special point in view4 ,if different orders of existing mammals were indeed made by gradual modification of some generalized primal form1 then it is evident that these useless remnants of once useful parts would be most common in the most highly modified forms4 ,now1 of all mammals1 the whales are perhaps the most modified or changed from the original mammalian form--so much modified1 in fact1 that the popular eye scarcely recognizes them as mammals at all4 ,here1 then1 we might expect1 and do indeed find1 many examples3 #a4 ,the baleen whales have no teeth1 and no use for them4 ,they have instead a wonderful armature of fringed whalebone plates 7baleen71 by means of which they gather their food4#bg ,yet the embryo of the whale has a full set of rudimentary teeth deeply buried in the jawbone1 and formed in the usual way characteristic of mammalian teeth--i4 e41 by an infolding of the epithelial surface of the gum--but the teeth are never cut2 in fact1 they reach their highest development in mid-embryonic life1 and are again absorbed4 ,why1 then1 this waste of developmental energy8 ,why should teeth be formed only to be reabsorbed without being cut8 ,the only conceivable answer is1 because the ancestors of the whale1 before the family of whales was fairly established1 had teeth which were gradually1 from generation to generation1 aborted1 because no longer used1 the baleen plates having taken their place4 ,if whales were made at once out of hand as we now see them1 is it conceivable that these useless teeth would have been given them8 #b4 ,again1 many whales have rudimentary pelvic bones1 but no hind-limbs4 ,why should there be pelvic bones1 when the sole object of these bones is to act as a basis for hind-limbs8 ,in some whales1 for example the right whale1 there are also rudiments of hind-legs1 but these are buried beneath the skin and flesh1 and therefore1 of course1 wholly useless4 ,the only explanation of these facts is that the ancestors of all the whales before they had become whales were quadrupeds1 which afterward took to the water1 and little by little the hind-legs1 for want of use1 dwindled away to the useless remnants which we now find4 #c4 ,again1 whales seem to be hairless1 yet rudimentary hairs are found in the skin4 ,their organs of smell are rudimentary1 but made on the pattern of those of mammals1 not of fishes--i4 e41 they are air-smelling1 not water-smelling organs4 ,from all these1 as well as many other facts1 it is evident that the whales descended in early ,tertiary times from some marsh-loving1 powerful-tailed1 short-legged1 scant-haired quadruped by modifications gradually induced by increasing aquatic habits4 ,examples of such rudimentary organs might be multiplied without limit4 ,as might be expected1 some are found even in man4 ,such1 for example1 are the muscles for moving the ear1 necessary in animals but useless in man1 and therefore rudimentary4 ,similarly useless in man are the scalp-muscle1 used by animals to erect the crest or bristles on the head1 and the skin-muscle of the neck and chest1 used by animals for shaking the skin of those parts4 ,most persons have lost the power of using these4 ,for my part ,i can use them all--ear-muscles1 scalp-muscle1 skin-muscle--but they serve no useful purpose4 ,again1 and finally1 in man and many mammals we find a slender1 worm-like appendage about three inches long1 attached to the ccum of the large intestine4 ,anatomists and physiologists1 under the influence of that philosophy which maintains that every part of the fearfully and wonderfully made human frame was directly contrived to subserve some useful purpose1 have puzzled themselves to find the use of this4 ,it probably has no use2 on the contrary1 it is a continual source of danger4 ,if the human body had been made at once out of hand1 it would not have been there4 ,how came it1 then8 ,it is the rudimentary remnant of an organ--a greatly enlarged ccum--which has served1 and in some mammals still serves1 a useful purpose4 ,all these cases are survivals2 they are organs which1 like many customs in society1 have outlived their usefulness1 but still continue by heredity4 ,but why multiply examples8 ,all along the track of evolution organs become useless by changes in the habits of their possessors4 ,they are not1 however1 shed or dropped bodily at once4 ,no2 they are retained by heredity1 but dwindle by disuse1 more and more1 until they pass away entirely4 ,but even when they are entirely gone in the adult1 they are often found still lingering in the embryo4 ,they are among the most obvious and convincing proofs of the origin of organic forms by derivation4 ,,chapter ,,viii4 ,,proofs ,,from ,,geographical ,,distribution ,,of ,,organisms4 ,it is well known that the kinds of organisms found in widely-separated countries differ more or less conspicuously4 ,the traveler in ,australia or in ,africa finds all1 the traveler in ,europe nearly all1 the animals and plants wholly different from those he has been accustomed to see at home4 ,even the visitor from the ,atlantic to the ,pacific coast1 if he observes at all1 will find nearly all organisms strange to him4 ,the facts of geographical diversity of organisms are so numerous and complex that1 at first sight1 they seem utterly lawless4 ,only recently this subject has been redeemed from chaos and reduced to something like order and law by the light thrown upon it by the theory of evolution4 ,we will give1 in very brief outline1 the most important facts1 and then show how they may be explained4 ,geographical ,faunas and ,floras4--,the group of animals and plants inhabiting any locality1 whether peculiar to that locality or not1 is called1 in popular language1 its fauna and flora4 ,but1 in a true scientific sense1 a fauna and flora is a natural group of animals and plants in one place1 differing more or less conspicuously from other groups in other places1 and separated from them by physico-geographical boundaries1 or by physical conditions of some kind4 ,the members of such a group can only exist in certain harmonic relations with external conditions1 and with one another4 ,these relations with one another are often complex and nicely adjusted1 so that change in one term is propagated through the whole series of terms1 giving rise often to the most unexpected results1 until finally a new equilibrium is established4 ,thus1 the destruction of certain insectivorous birds1 in mere wanton sport1 may give rise to the multiplication of insect pests1 and this to the destruction of certain kinds of plants1 and this to the diminution of certain herbivores1 and this in its turn to the disappearance of certain carnivores4 ,it is well known that the introduction of rabbits into ,new ,zealand and ,australia has produced the most unexpectedly disastrous effect upon certain crops1 on account of the absence of the fierce and active carnivores which keep in check their excessive multiplication in ,europe4 ,now1 among the physical conditions which limit faunas and floras1 and separate them from each other1 the most important and universal is temperature4 ,temperature-,regions4--,if we travel from equator to pole1 we pass through mean temperatures varying from #hj to #j4 ,this gives rise to a very regular zonal arrangement of plant-forms3 #a4 ,we have first a region in which palms and palm-like forms are abundant and characteristic1 and which therefore may be called the region of palms4 ,it corresponds with the tropic zone4 #b4 ,we next have a region in which hard-wood foliferous trees are most abundant and characteristic2 first mostly evergreens and then deciduous trees1 and therefore may be called the region of hard-wood forests4 ,this corresponds with the temperate-zone4 #c4 ,then we find a region characterized predominantly by pines and pine-like trees and birches1 and may be called the region of pines4 ,this is the sub-,arctic region4 #d4 ,then a region without trees1 but only shrubs and summer plants4 ,this is the ,arctic region4 #e4 ,and1 finally1 an almost wholly plantless region of perpetual ice--the polar region4 ,these regions are determined wholly by temperature1 and therefore1 in going up a mountain-slope to snowy summits1 we pass through similar regions in smaller space4 ,for example1 in going from sea-level to the summits of the ,sierra1 #ad1jjj to #ae1jjj feet high1 we commence in a region of predominantly hard-wood trees2 but at #c1jjj feet the forests become almost wholly coniferous1 at #aa1jjj to #ab1jjj feet the vegetation becomes shrubby1 and at #ac1jjj feet we reach perpetual snow4 ,we have taken plants first1 because these1 being fixed to the soil and incapable of voluntary seasonal migrations1 are more strictly and simply limited by temperature--i4 e41 the arrangement of different kinds in zones is more simple and conspicuous4 ,but the same rule holds also for animals4 ,in passing from equator to pole1 animal kinds also change frequently1 so that there are many temperature-faunas in which the animals are all very different4 ,in both animals and plants1 species1 genera1 families1 etc41 are limited by temperature4 ,these are familiar facts2 we recall them to the reader in order that we may base thereon a clearer definition of these limits4 ,more ,perfect ,definition of ,regions4--#a4 ,the area over which any form spreads is called its range4 ,now1 the range of a species is more restricted than that of a genus1 because1 when a species is limited by temperature1 another species of the same genus may carry on the genus4 ,for the same reason the range of a family is usually greater than that of a genus1 and so on for higher classification-groups4 ,for example1 pines range on the slopes of the ,sierra from about #b1jjj feet to #aa1jjj feet1 but not the same species4 ,in ascending1 we meet first the nut-pine 7,pinus ,sabiniana71 then the yellow-pine 7,p4 ponderosa71 then the sugar-pine 7,p4 ,lambertiana71 then the tamarack-pine 7,p4 contorta71 and last1 the ,pinus flexilis1 etc4 ,illustration3 ,,fig4 #fd4 #b4 ,where two contiguous temperature-regions come in contact1 there is no sharp line between2 on the contrary1 they shade gradually1 almost imperceptibly1 into one another1 the ranges of species overlapping and interpenetrating1 and the two species coexisting on the borders of their ranges4 ,this is represented by the diagram 7,fig4 #fd71 in which the horizontal lines represent the north and south ranges of species of two groups1 ,a and ,b1 separated by the dotted line4 #c4 ,species also pass out gradually on the borders of these ranges and others come in gradually1 so far as number and vigor of individuals are concerned4 ,if a a and b b 7,fig4 #fe7 represent the north and south range of two species1 and b a their overlap or area of coexistence1 then the height of the curves ,a and ,b will represent the number and vigor of the individuals in different parts of the range4 ,illustration3 ,,fig4 #fe4 #d4 ,while1 therefore1 there is a shading of contiguous groups into each other by overlap of species-ranges2 while there is also a gradual passing out of species so far as number and vigor of individuals is concerned1 yet1 in specific characters we observe usually no such gradation4 ,species seem to come in on one border with all their specific characters perfect1 remain substantially unchanged throughout their range1 and pass out on the other border1 still the same species4 ,in other words1 one species takes the place of another1 usually by substitution1 not by transmutation4 ,it is as if species had originated1 no matter how1 each in its own region1 and had spread in all directions as far as physical conditions and struggle with other species would allow4 ,this important subject will be more fully discussed later4 #e4 ,we have thus far spoken of species as limited by temperature alone1 but they are limited also by barriers4 ,if1 then1 there be an east and west barrier1 such as a high mountain-range1 or a wide sea or desert1 there will be no shading or gradation of any kind1 because the barrier prevents overlapping1 interpenetration1 and struggle on the margins4 ,for example3 ,the species north and south of the ,himalayas1 or north and south of ,sahara1 are widely different4 ,it is1 again1 as if they originated each where we find them and spread as far as they could1 but the physical barrier prevented mingling and shading4 #f4 ,there are temperature-regions south as well as north of the equator4 ,now1 although the climatic conditions are quite similar1 the species of corresponding temperature-regions north and south are wholly different4 ,it is1 again1 as if they originated where we find them1 and were kept separate by the barrier of tropical heat between4 ,if carried over1 they often do perfectly well4 ,continental ,faunas and ,floras4 ,if the land-surfaces were continuous all around the globe1 there is little doubt that each temperature region with its characteristic species would also be substantially continuous4 ,there would1 it is true1 be some local variations dependent upon soil and humidity1 etc41 but substantially the same species would exist all around4 ,the distribution would be almost wholly zonal4 ,but the intervening oceans are complete barriers to continental species4 ,hence we ought to expect1 and do find1 that the faunas and floras of different continents are almost totally different4 ,each apparently originated on its own continent1 and did not spread to other continents1 only because they could not get there4 ,it is necessary to explain this in more detail4 ,illustration3 ,,fig4 #ff4--,polar projection of the earth4 #a1 tropical2 #b1 temperate2 #c1 sub-arctic2 #d1 arctic2 #e1 polar regions4 ,fig4 #ff represents a polar view of the earth1 showing the eastern and western continents1 and the five temperature zones already described4 ,now1 if we examine the species in each region1 commencing at the pole1 we find that those of ,nos4 #e and #d are almost identical all around4 ,the reason is obvious4 ,the continents come close together there1 with ice-connection if not land-connection all around4 ,there is but one circumpolar region4 ,but1 as soon as we come down to ,no4 #c and ,no4 #b1 the species on the two continents are nearly all different1 because there is an impassable barrier between1 either in the form of ocean or of ,arctic cold4 ,for example1 the animals and plants inhabiting the ,united ,states are almost wholly different from those in ,europe1 not only in species1 but even largely in genera and to some extent in families4 ,there are some exceptions to this rule1 but these are of the kind which prove the rule1 or rather the principle on which the rule is founded4 ,these exceptions are mainly of three kinds3 #a4 ,introduced species4--,all our weeds1 many garden-plants1 and many animal pests are of this kind4 ,they were not found here when ,america was discovered1 only because they could not get here2 for1 when brought here1 they do so well that they often overrun the country and dispossess the native species1 as we ourselves have done the ,indians4 #b4 ,hardy or else wide-migrating species4--,hardy species have wide range2 they may belong to ,no4 #d as well as ,no4 #c4 ,if so1 they range down to ,no4 #c on both continents4 ,migrating birds1 such as ducks and geese1 etc41 breed in summer in ,no4 #d1 and migrate southward in winter on both continents from the common circumpolar ground4 #c4 ,alpine species4--,it is a curious fact that species on tops of snowy mountains in temperate regions of the two continents are wonderfully similar1 though so completely isolated4 ,we are not yet prepared to discuss this point4 ,we shall do so later4 ,suffice it to say now that it can be completely explained4 ,in region ,no4 #a the continental diversity is still greater4 ,not only species and genera1 but whole families and even orders1 are peculiar to each continent4 ,the great pachyderms--elephant1 rhinoceros1 hippopotamus--are peculiar to the ,eastern2 the edentates--sloths and armadillos--to the ,western4 ,the humming-birds1 those gems of the forests1 of which there are over four hundred species1 and the whole cactus family1 are peculiar to ,america1 while the tailless monkeys are equally characteristic of the ,eastern ,continent4 ,the continents do not come together again toward the south1 and1 therefore1 as might be expected1 the great difference between the two persists to the southern points4 ,the faunas of the southern points of ,south ,america1 ,africa1 and ,australia are very different4 ,subdivisions of ,continental ,faunas and ,floras4--,besides the subdivisions of continental faunas1 north and south1 determined by temperature as already explained1 if there be in any continent an impassable barrier running north and south1 there will be a corresponding difference in the species on the two sides1 east and west4 ,we give but one example3 ,the ,north ,american ,cordilleras or ,rocky ,mountains1 with their high ranges and desert plains1 constitute a very great barrier between the eastern and western portions of the ,united ,states4 ,hence1 we find an extraordinary difference between the species inhabiting ,california and those found in the eastern portion of the country4 ,speaking generally1 all the species and many of the genera are peculiar4 ,the exceptions1 too1 are significant4 ,leaving out introduced species1 of which there are many1 they are mostly strong-winged or widely-migrating birds1 such as the turtle-dove1 the turkey-buzzard1 the bald eagle1 and1 of course1 many water-birds4 ,special ,cases4--,if any body of land is widely separated from all other lands by deep seas1 we invariably find a corresponding peculiarity of its species4 ,thus1 the species inhabiting ,australia and ,madagascar are perhaps the most peculiar in the world4 ,we do not dwell further on these1 because we will discuss them hereafter4 ,there is a little group of very small islands--the ,galapagos--about six hundred miles off the western coast of ,south ,america1 and surrounded on all sides by deep sea4 ,these islands are stocked with a collection of curious animals not found elsewhere on the surface of the earth2 but among them are no mammals at all4 ,we might multiply examples without limit4 ,even the rivers emptying in the same sea sometimes have each its peculiar species of mussels4 ,in the ,altamaha ,river there are several species of unios--such1 for instance1 as the wonderful spinous unio--not found elsewhere4 ,how came they there8 ,howsoever they may have come there1 they are now kept isolated there by barriers of land and of salt water4 ,many other curious details will come up in our discussion of the origin of diversity4 ,marine ,species4--,precisely the same principles apply here2 but diversity in the case of marine species is perhaps less marked1 and certainly less general1 because of the universal oceanic connection4 ,open-sea species are therefore almost universal4 ,but many marine species are confined to shallow water1 and therefore to shore-lines4 ,the species on the two shores of the same ocean1 or the two coasts of the same continent1 are different1 being isolated east and west by barriers of deep sea or of land1 and north and south by temperature4 ,also about isolated lands1 like ,australia and ,madagascar1 the species are peculiar4 ,thus1 then1 species1 genera1 etc41 are limited in every direction2 north and south by temperature1 and in all directions by barriers1 in the form of oceans1 deserts1 and mountain-chains4 ,add to these1 peculiar climates and soils1 and we see that1 from this point of view1 the whole surface of the earth may be divided and sub-divided into regions1 sub-regions1 provinces1 etc4 ,it would carry us too far to explain the primary and secondary divisions adopted by ,mr4 ,wallace1 and the somewhat different ones suggested by ,mr4 ,allen4 ,our main object is to discuss the cause of this diversity1 and especially to show the light shed upon it by the theory of evolution4 ,we have only given a sketch of the facts sufficient for this purpose4 ,theory of the ,origin of ,geographical ,diversity4 ,it will be observed that all along we have assumed a sort of provisional theory4 ,we have said in every case1 it is as if organic forms originated where we find them1 and have gone thence wherever they could--as far in every direction as physical conditions and struggle with competing species would allow4 ,this view has been formulated as the 8theory of specific centers of origin40 ,there would be less objection to this as a first provisional theory did it not assume a supernatural mode of origin4 ,but1 in the minds of those who hold it1 it has usually assumed expressly or tacitly the form of 8specific centers of creation10 thus implying the immutability of specific types and the supernaturalism of specific origin 7page #fh74 ,in this latter or usual form it completely fails to account for the facts given above4 ,for1 if this were the mode of origin1 each species ought in every case to be perfectly adapted to its own environment1 and to no other4 ,but1 on the contrary1 introduced species often flourish better than in their own country1 and better than the natives of their new homes4 ,in the less objectionable form of 8specific centers of origin10 without defining the mode of origin1 it accounts well for many of the more obvious facts of geographical diversity1 as it now exists1 but not all4 ,according to this view1 the amount of diversity ought to be in strict proportion to the completeness of isolation1 or impassableness of the separating barriers2 but this is not exactly true4 ,there is another element1 not yet mentioned1 which is just as important as impassableness1 but which until recently has been left entirely out of account4 ,this is the element of time--the amount of time since the barrier was set up1 or during which it has continued to exist4 ,these two elements1 it is true1 are closely connected with each other2 for1 since all changes in physical geography have taken place very slowly--since barriers in the form of mountain-ranges and seas have increased by slow process of growth--it is evident that impassableness is1 to some extent1 a measure of time4 ,but they are by no means in strict proportion4 ,the one or the other may predominate4 ,now1 this time-element connects geographical distribution with changes of physical geography and climate in geological times1 and especially with the latest of these changes1 viz41 those occurring during the ,glacial epoch4 ,during that remarkable epoch extraordinary changes of climate1 from extreme ,arctic rigor to great mildness1 enforced wide migrations of species southward and northward2 while concomitant changes of physical geography1 by elevation of the earth's crust over wide areas1 opened highways between previously-isolated continents1 permitting migrations in various directions1 and by subsequent depression again isolating the migrated species in their new homes4 ,it is evident1 then1 that the recognition of the element of almost unlimited time at once introduces into the question of geographical distribution the idea of evolution4 ,if the study of geographical distribution1 as it now exists1 and as a part of science of physical geography1 gave rise naturally to the theory of 8specific centers of origin10 the study of the same1 in connection with geological time1 and as a part of geological science1 now demands its explanation by the theory of evolution4 ,it must be borne in mind1 then1 that geographical diversity of organisms is not a question of the present epoch only4 ,there has been geographical diversity in every previous geological epoch2 it is1 therefore1 a question of geology as well as of biology4 ,it is probable1 however1 that diversity has increased with the course of geological times1 and is greater now than ever before4 ,in other words1 in the evolution of the organic kingdom1 the law of differentiation has prevailed here1 as in other departments of biology4 ,a clear statement of the causes of the present distribution of organisms must embrace also the causes of geographical diversity generally4 ,we give1 therefore1 at once a brief statement of what seems to us the most probable view1 and shall then proceed to show how it explains the present distribution4 ,most ,probable ,view of the ,general ,process4--,bearing in mind1 then1 this time-element1 the phenomena of geographical diversity are best explained by the following suppositions3 #a4 ,a gradual progressive movement 7evolution7 of the organic kingdom1 marching1 as it were1 abreast1 at equal rate along the whole line--i4 e41 in all parts of the earth1 and throughout all geological times1 under the action of all the forces or factors1 and following all the laws1 of evolution already explained 7pages #ai and #gc74 ,if this were all1 there would be no geographical diversity1 although organic diversity might be as great as it is now4 ,there would be differentiation of forms and structure everywhere1 but no differentiation of groups in different localities4 #b4 ,under the influence of different conditions in different places1 more or less isolated from one another by climatic or physical barriers1 the onward movement 7evolution7 of organic forms takes different directions and different rates1 and gives rise to local groups1 which become more and more differentiated1 without limit as time goes on4 ,this element1 acting by itself throughout all geological times1 would ere this have produced an extreme geographical diversity1 such as does not anywhere exist4 #c4 ,from time to time1 at long intervals1 extensive changes of physical geography and climate1 produced by crust elevations1 partly enforce by change of temperature1 and partly permit by opening of gateways1 extensive migrations and dispersals of species1 by which mingling and struggle for life and final readjustment takes place1 and extreme diversity is prevented4 ,such mingling of different faunas and floras on the same ground1 and the severe struggle for life that thus ensues1 and the survival of the fittest in many directions1 are1 as already shown1 among the most powerful factors of evolution4 ,they tend to increase organic diversity1 but to diminish geographical diversity4 #d4 ,at the close of such great periods of change as indicated in the last1 by contrary movement of the earth-crust--i4 e41 subsidence--new barriers are set up and new isolations are produced1 and the process of divergence again commences and increases steadily so long as the barriers continue to exist4 ,now1 the last of these periods of great changes and extensive migrations1 and subsequent isolations1 was the ,glacial epoch4 ,it was this epoch1 therefore1 which mainly determined the present geographical distribution of species4 ,thus1 the present distribution is a key to the directions of the last great migrations1 and therefore to the nature of the changes in physical geography and climate which then occurred2 and1 conversely1 the character of these changes1 determined in other ways1 furnishes the only key to the present distribution of species4 ,before applying the foregoing principles in the explanation of special cases1 it may be well to give a very brief outline of the condition of things during the ,glacial epoch4 ,in ,america1 during this epoch1 by increasing cold the southern margin of the great northern ice-sheet crept slowly southward1 until it reached the latitude of about #ch to #dj4 ,arctic species were thus driven southward slowly1 from generation to generation1 until they occupied the whole of the ,united ,states1 as far as the shores of the ,gulf1 while temperate species were forced still farther south1 into ,central and ,south ,america4 ,this period of extreme rigor and southward migration was followed by a period of great mildness1 during which the ice and its accompanying ,arctic conditions retreated northward1 followed by ,arctic species4 ,more than one advance and retreat1 apparently1 occurred during this time4 ,again1 during the same time1 brought about by northern elevation1 there was broader connection than now exists between ,north and ,south ,america1 and free migrations between1 in both directions1 enforced by extreme changes in temperature4 ,also1 during this or previous time1 there were broad connections between ,north ,america and ,asia1 in the region of ,behring ,strait1 and between ,america and ,europe1 in high-latitude regions1 and extensive migrations of faunas and floras between were thus permitted4 ,the necessary result of all these migrations of species1 partly enforced by changes of climate1 partly permitted by opening of gateways since closed1 was exceptionally rapid changes in organic forms4 ,this was the result of two causes3 ,first1 the severer pressure of a changing physical environment2 and1 second1 a severer struggle for life between the natives and the invaders4 ,in ,europe1 during the same time and from similar causes1 there were at least three or four different faunas struggling together for mastery on the same soil4 ,first1 there were the ,pliocene indigenes1 who had1 if any1 pre-emption right to the soil2 second1 invaders from ,arctic regions1 driven southward by increasing cold2 third1 invaders from ,asia1 permitted by the removal of the old sea-barrier which once extended from the ,black ,sea to the ,arctic1 and of which the ,caspian and ,aral are existing remnants1 and thus opening a gateway for migration which has remained open ever since2 fourth1 invaders from ,europe and ,asia into ,africa1 and sometimes back again into ,europe1 by opening of gateways through the ,mediterranean1 which have been since closed4 ,one of these highways was through ,gibraltar1 and one from ,italy to ,africa through ,sicily4 ,as in ,america1 so here1 in even greater degree1 the severe pressure of changing environment and the severe struggle for life produced rapid changes of organic forms4 ,many species were destroyed2 others saved themselves by modifications adapted more perfectly to the changed conditions4 ,there is little doubt that man came into ,europe with the ,asiatic invasion1 and was one of the principal agents of change1 especially in the way of destruction of many old forms4 ,such is a very brief outline of the last great geological change and its general results4 ,being the last1 this one has left the strongest and most universal impress on the present geographical distribution4 ,but similar changes by crust oscillations1 if not also by extreme changes of climate1 have repeatedly occurred in geological times1 and some of the most remarkable geographical faunas and floras are the result of these earlier geological changes4 ,we will now give a few examples illustrating these principles3 #a4 ,australia is undoubtedly more peculiar in its fauna and flora than any other known country4 ,not only are all its species peculiar1 not found elsewhere on the face of the earth1 but its genera1 its families1 and even many of its orders of animals and plants1 are also peculiar4 ,these facts are so familiar that it is unnecessary to dwell on them4 ,i need only mention1 among plants1 the whole of the simple-leaved acacias1 already mentioned on page #hf1 of which there are so many species1 and the whole family of the eucalyptids1 of which there are several hundred species4 ,among animals ,i need mention only the order of monotremes1 or egg-laying mammals1 and nearly the whole order of marsupials1 or pouched animals1 of which there are over two hundred species4 ,on the other hand1 the true typical mammals are entirely absent1 with the exception of a few bats and a few rats1 which have evidently been accidentally introduced from abroad4 ,another very noteworthy fact1 which must be taken in connection with the last1 is that ,australian forms are far less advanced in the race of evolution than those of any other country--i4 e41 that many old forms which have long ago become extinct elsewhere are still retained there4 ,a few examples will suffice4 ,the marsupials just mentioned are an old form once universally distributed1 but now nearly extinct everywhere1 except in ,australia2 the cestracion1 or ,port ,jackson shark1 and the ceratodus1 are ,palozoic and ,mesozoic forms retained only in ,australia4 ,what is the explanation of these remarkable facts8 ,we find the sufficient answer in the fact that ,australia has been long isolated from all other countries4 ,while geographical changes in geological times have mingled more or less the organic forms of other countries1 and the sharp struggle for life has produced more rapid advance and the production of many new and higher forms better armed for the battle of life1 ,australia has remained isolated from competition1 and therefore comparatively unprogressive4 ,can we tell when ,australia was finally isolated8 ,approximately we can4 ,the class of mammals is divided into two groups1 which differ widely from each other2 so widely1 that they are called sub-classes4 ,these are placental mammals1 or true typical mammals1 and non-placental or reptilian mammals4 ,the non-placentals include only the marsupials and the monotremes 7ornithorhyncus and echidna74 ,the monotremes actually lay eggs and incubate them4 ,in the marsupials the embryo has no placental connection with the mother1 and is born in a very imperfect condition1 utterly unfit for independent life1 and placed in the pouch 7marsupium71 and permanently attached there to the teat until it is capable of independent life2 after which only it voluntarily nurses like other new-borns4 ,in other words1 the gestation commenced in the womb is completed in the pouch4 ,the uterine gestation in the opossum is only seventeen days1 while the marsupial gestation is about two and a half months4 ,in a kangaroo seven feet high in sitting position the embryo at birth is only one inch long--a pink1 hairless1 almost amorphous mass4 ,the monotremes are pure oviparous animals1 like birds and reptiles4 ,the marsupials might well be called semi-oviparous4 ,in pure egg-layers the whole embryonic development is outside of the body2 in pure young-bearers the whole is within the body2 in marsupials it is partly within and partly without4 ,now--#a4 ,the monotremes are found nowhere but in ,australia and the neighboring ,new ,guinea4 #b4 ,the marsupials are also all confined to the ,australian region1 except a few oppossums in ,america4 #c4 ,there are some two hundred and thirty species of non-placentals in the ,australian region4 #d4 ,as already said1 there are no true mammals at all in ,australia1 except a few bats and rats which have come accidentally from abroad4 #e4 ,but non-placentals existed abundantly in ,mesozoic times everywhere1 both in ,europ-,asia and in ,america1 while true mammals did not appear at all on the surface of the earth until the ,tertiary1 when they almost immediately became very abundant everywhere1 except in ,australia4 ,evidently1 therefore1 ,australia was isolated before the ,tertiary4 ,the enormous difference between its fauna and flora and those of other countries is due to at least three things3 #a4 ,so long an isolation necessarily produced great divergence of forms4 ,this alone1 however1 would not affect the grade of organization4 #b4 ,saved from wide migrations1 and especially invasions from ,eurasia1 the great field of competitive struggle1 it was left far behind in the race of evolution4 ,hence many of its forms are archaic2 its mammalian fauna1 for instance1 is still in the ,mesozoic stage4 #c4 ,its distance from other large continents is so great that accidental colonization has been very slight1 only extending to a few bats and a few rats4 ,i stop a moment to insist on the effect of competitive struggle in developing organic forms strong for the battle of life4 ,of all the continents1 ,eurasia has been the scene of most frequent geological changes1 and therefore the arena of fiercest competitive struggle through wide and frequent migrations4 ,eurasian species1 therefore1 are the strongest of all4 ,they have conquered wherever they have gone4 ,species in isolated regions are usually the weakest4 ,the great moas and the dodo could not have continued to exist unless protected in a sort of bomb-proof4 ,kangaroos would now be quickly exterminated by the introduction of fierce ,eurasian carnivores4 #b4 ,africa4--,the fauna of that part of ,africa north of ,sahara is essentially ,mediterranean--i4 e41 a sub-group of the ,eurasian4 ,sahara1 rather than the ,mediterranean ,sea1 is the true intercontinental barrier4 ,the true ,african region1 therefore1 is south of ,sahara4 ,now1 according to ,mr4 ,wallace1 whom ,i mainly follow here1 the true ,african mammalian fauna consists of two very different groups of animals4 ,the one is a group of very small1 curious animals1 mostly low forms of insectivores and lemurs1 very peculiar to this region1 though more resembling those of ,madagascar than of any other region2 the other is a group of large and powerful animals which dominate the region4 ,these latter are similar to1 though not identical with1 those which inhabited ,eurasia in ,pliocene times4 ,the great carnivores1 pachyderms1 and ruminants of the region are examples of this group4 ,now1 the explanation of these facts is as follows3 ,the indigenes of ,africa are the animals of the first group4 ,africa1 in ,tertiary times1 was isolated from the great field of combat1 ,eurasia1 and therefore its animals were small1 of low grade1 and peculiar4 ,during later ,tertiary 7,pliocene7 times1 then1 ,africa was inhabited by animals of the first group1 while ,eurasia was dominated by animals of the second group4 ,these two groups were then separated by the ,desert of ,sahara1 or else by a sea in that region4 ,some time during the ,glacial epoch geographical changes removed this barrier1 and climatic changes drove the ,eurasian animals southward into ,africa1 where1 finding congenial climate1 they took possession of the continent1 dominating the feebler natives4 ,subsequently they were isolated there by the formation of the desert1 and the process of divergence commenced1 and has gone on to the formation of many new forms4 ,meanwhile the change1 partly by extinction and partly by modification1 has gone on still more rapidly in ,eurasia1 but in a different direction4 ,hence1 ,africa is regarded as one of the primary faunal regions4 #c4 ,madagascar4--,this1 next to the ,australian1 is probably the most peculiar faunal region known4 ,there is probably not a single mammalian species found there which is known to occur anywhere else4 ,it is remarkable also as the principal home of that strange1 generalized1 ancient form of monkeys--the lemurs4 ,and yet its animals1 though very different1 have a distant resemblance to those of ,africa2 not1 however1 to the present dominant type1 but to those we have called the indigenes4 ,not one of the northern invaders is found there4 ,the obvious conclusion from these facts is1 that ,madagascar was formerly united with ,africa1 and both were occupied by the same mammalian fauna 7which may be called ,african indigenes1 although they were considerably different from their descendants of the present day71 but became separated before the northern invasion4 ,the effect of this invasion was to hasten the steps of change in the indigenous fauna of ,africa1 partly by extermination1 partly by modification1 while the isolated portion in ,madagascar went on at the usual slow rate of change in isolated regions4 ,the time since the separation 7which was certainly during the ,tertiary period7 has been sufficiently long to produce very great divergence in both1 but especially in the ,african indigenes4 ,in the fauna of ,madagascar1 therefore1 we have a nearer approach to the original fauna of both4 ,on account of this long isolation1 we have here many ancient types which are extinct elsewhere4 ,the lemurs are such an ancient type4 ,these are a wonderfully-generalized type of monkeys--a connecting link between monkeys and other mammals1 especially insectivores4 ,as might be supposed1 from the law of differentiation1 already explained 7page #aa71 they are the earliest form1 the progenitors1 of monkeys4 ,in fact1 in early ,tertiary times1 they were found not only in ,africa and ,madagascar1 but all over the earth1 as the only representatives of the monkey family4 ,the true monkeys were not introduced until the mid-,tertiary4 ,in ,eurasia and in ,america 7which at that time was probably connected with ,eurasia7 wide migrations and frequent conflicts of faunas produced comparatively rapid evolution of new and higher forms1 while in isolated ,africa old types continued until the invasion4 ,madagascar was spared this invasion1 and therefore old types are still preserved there4 ,at present1 at least three quarters of all lemurs are confined to ,madagascar1 although a few species are still found in ,africa and in the great ,east ,indian islands4 #d4 ,island-,life4--,mr4 ,wallace has divided islands into two kinds1 continental and oceanic islands4 ,the division is undoubtedly a good one1 although we may not always be able to refer an example with certainty to the one or the other class4 ,continental islands are those on the borders of continents1 and separated from the latter only by shallow water4 ,oceanic islands are those1 usually very small1 found in the midst of the ocean1 with abyssal depth all about4 ,continental islands may be regarded as appendages to the neighboring continent--as outliers of continents separated by submergence1 and have1 in fact1 been thus formed4 ,oceanic islands have been formed geologically recently by volcanic action building up from the sea-bottom4 ,continental islands have a continental structure--i4 e41 they are composed of stratified as well as of igneous rocks4 ,their structure is a record of geological history1 like that of the neighboring continent4 ,oceanic islands are composed wholly of volcanic rocks2 or1 if there be any stratified rocks1 these are only of the most recent date4 ,as examples of continental islands we have ,new ,zealand as an appendage of ,australia1 the great ,east ,indian 7,borneo1 ,java1 ,sumatra1 etc47 and the ,japanese ,islands1 etc41 as appendages of ,asia2 the ,british ,islands1 appendages of ,europe2 the ,west ,indian ,islands1 appendages of ,america2 ,madagascar1 an appendage of ,africa1 etc41 etc4 ,as examples of oceanic islands we have the ,azores and ,bermudas in the ,atlantic1 and the ,polynesian islands in mid-,pacific4 a4 ,continental ,islands4--,now1 the fauna of continental islands1 as might be expected from the mode of origin of these islands1 is similar to1 though not identical with1 that of the neighboring continent2 the amount of difference being in proportion to the length of time since they were separated and the width of the separation4 ,madagascar1 for example1 has been long separated from its parent continent1 and by a wide and deep channel4 ,its fauna1 therefore1 differs greatly from that of ,africa1 although resembling it more than that of any other country4 ,the separation of ,new ,zealand from ,australia has been not quite so long1 and the divergence1 therefore1 is not so great4 ,these two will be sufficient illustrative examples of long separation1 and therefore of great differentiation of forms4 ,illustration3 ,,fig4 #fg4--,map of outline of coast of ,western ,europe1 if elevated #fjj feet 7after ,lyell74 ,on the other hand1 the ,british ,isles are an excellent example of comparatively recent separation4 ,these isles have probably been several times united and separated from ,europe1 but we are here concerned only with the more recent4 ,they are now separated from the continent and from one another only by shallow seas4 ,an elevation of less than six hundred feet--geologically a very small change--would bare the bottoms of the ,irish and ,english ,channels and the ,north ,sea1 and connect these islands with one another and with the continent 7,fig4 #fg74 ,now1 it is well known that there were during the ,glacial epoch1 and subsequently1 several oscillations of level sufficient to connect and separate these islands4 ,in the mid-,glacial epoch the ,british ,islands1 by submergence1 were nearly obliterated1 being reduced to an archipelago of small islets representing the high mountains of ,wales and ,scotland4 ,the ,pliocene fauna and flora were1 therefore1 largely exterminated4 ,during the close of that epoch they were elevated above the present condition and broadly connected with the continent 7,fig4 #fg71 and the newly-exposed land was taken possession of by ,european species1 man among the number4 ,still later--i4 e41 at the beginning of the present epoch--the islands by subsidence were again separated1 but not widely1 from the continent4 ,this is the condition now4 ,what1 then1 was the result8 #a4 ,the fauna and flora of the ,british ,isles are substantially the same1 but less rich in species than that of ,continental ,europe1 some of the ,european species being wanting4 ,this shows that the last connection was not a long one2 the colonization had not been completed before re-isolation4 #b4 ,this poverty of species is more conspicuous in ,ireland1 because colonization is progressive in space as well as in time4 ,some species had not reached so far when ,ireland was re-isolated from ,england4 ,the conspicuous absence of snakes1 for example1 is thus accounted for4 ,there is1 we all know1 another theory to account for this1 but we prefer the natural one4 #c4 ,the difference between ,british and ,european fauna and flora is very small1 it is true1 but there is some difference1 varietal if not specific4 ,the reason is1 that the time since separation is too small to produce much divergence1 and the width of the existing barriers not great enough to prevent colonization by accidental causes4 ,the continental islands of the southern coast of ,asia are good examples of an intermediate condition as to the length of time since separation1 and of the consequent degree of differentiation of the faunas and floras4 ,coast-,islands of ,california4--,we give one more example1 and dwell upon it a little1 because it occurs on our own coast4 ,the recent studies of ,mr4 ,e4 ,l4 ,greene on the flora of the islands off the coast of ,california have brought to light some facts which are an admirable illustration of the principles laid down above4 ,on looking at a good map of ,california1 any one will observe eight or ten islands1 some of them of considerable size1 strung along the coast from ,point ,conception southward1 and separated from the mainland by a sound twenty to thirty miles wide4 ,they are in structure true continental islands--outliers of the mainland separated by a subsidence of a few hundred feet4 ,moreover1 the date of their separation is known4 ,they were certainly connected with the mainland during the later ,pliocene and early ,quaternary1 for bones of the mammoth1 characteristic of that time1 have been found on one of them4#bh ,they were therefore separated during the ,glacial epoch4 ,the main peculiarities of the flora of these islands are the following3 #a4 ,out of nearly three hundred species of plants gathered by ,mr4 ,greene1 about fifty are wholly peculiar to these islands4 #b4 ,of the remaining two hundred and fifty species1 nearly all are distinctively ,californian4 ,in other words1 the distinctively ,californian forms are very abundant1 while the common ,american forms are rare--i4 e41 the island flora is distinctively ,californian1 with many peculiar species added4 ,i explain these facts as follows3 ,the whole coast-region of ,california is geologically very recent1 having emerged from the sea as late as the beginning of the ,pliocene epoch4 ,as soon as emerged it was of course colonized from adjacent parts4 ,since that time its peculiar flora has been formed by gradual modification4 ,the environment has been sufficiently peculiar1 the isolation sufficiently complete1 and the time sufficiently long1 to make a very distinct group of organisms4 ,it is one of ,mr4 ,wallace's primary divisions of the ,ne-arctic region4 ,during late ,pliocene and early ,quaternary times1 as already said1 the islands were still a part of the mainland1 and the whole was occupied by the same species1 viz41 the distinctively ,californian species now found in both1 together1 as ,i suppose1 with the peculiar island species4 ,during the oscillations of the glacial times the islands were separated by subsidence of the continental margin4 ,simultaneously with this subsidence1 or subsequently thereto1 came the invasion of northern species1 driven southward by glacial cold4 ,then came the mingling of invaders with natives1 the struggle for mastery1 the extermination of many forms--viz41 the peculiar island species--and the slight modification of others1 and the final result is the ,california flora of to-day4 ,but the island flora was spared this invasion by isolation4 ,therefore the invading species are mostly wanting1 the distinctive island species were saved1 and the result is the island flora of to-day4 ,the island flora1 therefore1 somewhat nearly represents the ,pliocene indigenes of both4 ,it will be observed that this case is somewhat like that of ,madagascar1 but with a characteristic difference4 ,in the case of ,madagascar1 the separation has been long4 ,the extreme peculiarity of its fauna is the result partly of progressive divergence and partly of many forms saved by isolation4 ,in the case of the coast-islands of ,california1 the time has not been long enough for any great divergence by modification4 ,the peculiarity of its species is due almost wholly to species saved by isolation4#bi b4 ,oceanic ,islands4--,we have seen that faunas and floras of continental islands are somewhat similar to those of the neighboring continent1 though with varying degrees of difference--the amount of difference1 or divergence by evolution1 being in proportion to the amount of time and the impassableness of the separating barriers4 ,but oceanic islands have never been connected with any continent4 ,they are new land formed in the midst of the ocean by volcanic action4 ,when they first appeared they were1 of course1 without inhabitants of any kind1 animal or vegetal4 ,how were they peopled8 ,we answer by waifs from here and there--by castaways from other lands4 ,the dominance of particular kinds will depend on the direction of winds and currents1 bringing from some lands more than others1 and upon the kinds of animals or seeds of plants most liable to be successfully carried across wide seas4 ,their faunas and floras1 therefore1 are characterized by a mixture of species resembling1 though not usually identical with1 those of various lands1 with a predominance of those of some one land1 and by the singular and complete absence of mammals and amphibians1 these being unlikely to be transported by floating timber1 as are small reptiles and insects1 etc4 ,among mammals1 however1 there is a significant exception in favor of bats1 the reason being both their power of flight and their habit of concealment in hollow trees1 etc4 ,to this explanation1 however1 we must add that divergence by isolation will meanwhile go on in proportion to time4 ,the ,azores1 for example1 have been peopled from ,europe1 ,africa1 and ,america1 but mostly from ,europe1 on account of the prevailing winds and currents being favorable to colonization from that direction4 ,there are many curious peculiarities in the species1 however1 because colonization is very slow1 and divergent variation has been going on pari passu4 ,the ,bermudas1 on the other hand1 have been colonized mainly from ,america1 because of the current of the ,gulf ,stream4 ,these few examples are sufficient for our purpose1 which is only to illustrate the causes of geographical distribution4 ,if any one desires to pursue this interesting subject1 we would refer him to that most fascinating book1 ,mr4 ,wallace's 8,island-,life40 #e4 ,alpine ,species4--,these afford an admirable illustration of the fact that in isolated faunas and floras the amount of difference is proportioned not only to the completeness of isolation1 but also and mainly to the time of isolation4 ,it is well known that ,alpine species--i4 e41 those species inhabiting the region bordering the perpetual snow of lofty mountains--are very similar to one another1 even in the most distant localities1 where their isolation from one another is as complete as possible2 as1 for example1 in the high ,alps of ,europe1 the high mountains of ,colorado and ,california4 ,why is this8 ,we find the key to this mystery in the additional fact that they are similar also to ,arctic species4 ,a somewhat full explanation is here necessary4 ,during ,miocene times1 magnolias and taxodiums 7bald cypress71 like those in forests and swamps of ,carolina and ,louisiana1 and sequoias and libocedrus like those now in ,california1 and many other temperate-region forms of plants1 grew abundantly in ,greenland1 and northward certainly to #ge north latitude4 ,at that time there could not have been any perpetual polar ice1 and therefore no ,arctic species1 unless on high mountains in polar regions4 ,in ,pliocene times perpetual polar ice1 and therefore ,arctic species1 probably commenced to appear4 ,as the cold of the ,glacial epoch came on and increased in severity1 the polar ice extended southward as a general ice-sheet1 until it reached in ,america #dj and in ,europe about #ej north latitude4 ,in the ,united ,states its margin can be traced as a distinct moraine through ,long ,island1 middle ,new ,jersey1 middle ,pennsylvania2 thence1 less distinctly1 following the ,ohio ,river1 crossing the ,mississippi2 thence following the ,missouri1 on its south side1 into ,montana4 ,by the increasing cold1 ,arctic species were driven slowly southward1 generation after generation1 until they occupied the whole of the ,united ,states to the ,gulf1 and the whole of ,europe to the ,mediterranean4 ,as these species on the two continents came from a common home in polar regions1 they were similar to one another1 except in so far as some slight divergent modification may have been produced during their southward travel4 ,when the glacial rigor declined1 and the ice-sheet gradually retreated to its present position1 ,arctic species1 following the snow-edge1 went also northward1 on both continents1 to their present home in polar regions4 ,but there was an alternative way of migration left open which was embraced by certain plants and insects4 ,while on both continents most individuals went northward1 some of them went upward1 following the snow-edge into high mountains1 and were left stranded there4 ,thus it has come to pass that the plants and insects of high mountains in temperate regions of different continents1 though so widely separated and impassably isolated1 are extremely similar to one another4 ,but1 though similar1 they are rarely identical4 ,the time has been long enough for some but not very great divergent modification4 ,it is impossible to conceive a more beautiful illustration of the principles we have been trying to enforce4 99 99 99 99 99 ,thus1 then1 undoubtedly all the phenomena of geographical distribution of species are most rationally explained on the principle of slow evolution--changes1 different in different places1 and increasing with the time of isolation and its completeness4 ,objection4--,the only objection which can be raised against this view is the manner in which contiguous geographical faunas and floras pass into one another when they are limited not by barriers but by temperature4 ,in passing from equator to poles1 over continuous land1 we of course pass through many successive faunas and floras1 limited wholly or mainly by temperature4 ,now1 if species are indeed indefinitely modifiable1 then on the borders of contiguous faunas or floras1 where one species disappears and another closely allied but adapted to a colder temperature takes its place1 the one species 7say the anti-evolutionists7 ought to be gradually transmuted into the other1 so that all the gradations may be traced4 ,but this is certainly not usually the fact4 ,on the contrary1 a species may indeed pass out gradually1 and another come in gradually1 so far as number and vigor of individuals are concerned2 but1 in specific character1 they may be said1 usually at least1 to come in suddenly1 with all their characters perfect1 remain unchanged throughout their whole range1 and pass out suddenly at its borders4 ,another species takes its place1 overlapping in range and coexisting on the borders of both2 this also continues unchanged1 as far as it goes1 and so on4 ,the change from one fauna to another is apparently not by transmutation of one species into another by gradations1 but by substitution of one perfect species for another perfect species4 ,as a broad general statement1 the condition of things is precisely such as would be the case if specific types were substantially immutable by physical conditions1 but were originated in some inscrutable way 7created7 in the regions where we now find them1 and have spread in every direction as far as physical conditions and struggle with other species would allow them--their ranges therefore interpenetrating and overlapping one another on their borders4 ,two characteristic examples will make our meaning clear4 ,there is not a more characteristic tree known than the sweet-gum1 or liquidambar4 ,this tree grows from the borders of ,florida to the shores of the ,great ,lakes4 ,it may indeed be most numerous and vigorous somewhere in the middle region1 and may die out gradually in number and vigor of individuals on the borders of its range1 but in specific character it is substantially the same throughout1 easily recognizable by its dense wood1 its winged bark1 its five-starred leaf1 its spinous burr1 and its fragrant gum4 ,physical conditions may diminish its number and vigor1 and limit its extension1 but seem powerless to essentially modify its specific character4 ,it seems to give up its life rather than change its nature4 ,another striking example3 ,the sequoias 7redwood and big-tree7 are entirely confined to ,california1 and there are only two species now existing1 viz41 the redwood 7,s4 sempervirens7 of the ,coast ,ranges1 and the big-tree 7,s4 gigantea7 of the ,sierra ,nevada4 ,doubtless they are most numerous and vigorous somewhere in the middle of their range1 and die out gradually in number and vigor on the borders north and south1 being replaced there by other genera better adapted to the physical conditions2 but in specific character they remain essentially unchanged throughout4 ,they are everywhere the same--easily recognizable by wood1 bark1 leaf1 and burr4 ,both in this case1 and in the previous one of the sweet-gum1 it is as if they were created perfect in their present localities1 and have spread in all directions as far as physical conditions and the struggle with other competing species would allow2 but physical conditions seem powerless to change them into any other species by adaptive modification4 ,answer4--,we have1 we believe1 stated the objection fairly4 ,the answer is1 that the elements of time and of migrations have not been taken into the account4 ,in fact1 this objection was conceived and formulated before the idea of geological time was fully assimilated by the human mind1 and our theories of origin adjusted to it4 ,if these species did indeed originate where we now find them1 and in the present geological epoch1 the argument might at least be entertained2 but this is not the fact4 ,we know something of the geological history of all these species1 and the history of the migrations of some of them4 ,we know that sweet-gums were abundant and of many species in the ,united ,states in ,tertiary times1 and all have become extinct except this remnant4 ,whatever of modifications there were must be looked for at or about the time of its origin in ,tertiary times1 not now4 ,species1 like individuals1 are plastic only when young4 ,this one has already become rigid1 and all the more so as it is a remnant widely separated from other species4 ,for competition is strongest and most effective with nearest allies4 ,present species are mostly isolated remnants--terminal twiglets of the tree of life4 ,twiglets are of course widely separated at their visible ends4 ,their points of union with other twiglets must be sought below4 ,in the case of the sequoias1 we know something also of the history of their migrations4 ,in ,miocene times they were abundant1 and of many species in circumpolar regions4 ,some twenty-four species of fossil sequoias are known1 fourteen of which are ,tertiary4 ,by the cold of the ,glacial epoch they were driven slowly southward1 both in ,america and in ,europe--in ,america as far as ,southern ,california4 ,after the ,glacial epoch1 and the return of temperate conditions1 they doubtless attempted to go northward again2 but these great changes were too much for them2 they were wholly exterminated in ,europe1 and nearly so in ,america4 ,a few were left stranded high up on the slopes of the ,sierra ,nevada1 and on the cool1 moist slopes of the ,coast ,ranges4 ,the species now in ,california are not identical with those found in the ,miocene strata of ,greenland2 but the difference is only what we might expect after such extensive migrations and such long and severe struggle for life4 ,further1 it is noteworthy that the ,miocene species fall into two groups1 viz41 the yew-like leaved and the cypress-like leaved4 ,these are represented to-day in ,california1 the one by the redwood1 the other by the big-tree4 ,they are evidently direct descendants of the ,miocene species1 though somewhat modified4 ,but it will be objected that there ought to be some cases of transitional forms showing transmutation--in fact1 there ought to be some cases of species now forming under our eyes4 ,there are1 we believe1 examples of such cases4 ,but intermediate forms are not likely to be maintained long1 especially if migrations occur to give rise to severe conflict of forms4 ,in that case the intermediate forms are soon eliminated1 and species become distinct4 ,this important point will be discussed more fully in the next chapter4 ,,chapter ,,ix4 ,,proofs ,,from ,,variation ,,of ,,organic ,,forms1 ,,artificial ,,and ,,natural4 ,as already stated1 page #dj1 the use of the method of experiment in the field of biology is1 unfortunately1 very limited4 ,nevertheless1 it is already beginning to be used more and more in the department of physiology1 and may be used also1 to a limited extent1 in the department of morphology4 ,it is true that direct scientific experiments1 for the express purpose of producing permanent modifications of form1 and thus testing the theory of evolution1 are of comparatively little value as yet1 because the all-important element of time is wanting4 ,the steps of evolution are so slow1 and the time necessary to produce any sensible effect is usually so great1 that1 in comparison1 man's individual lifetime is almost a vanishing quantity4 ,but1 from time immemorial1 experiments have been unconsciously made by man on domestic animals and food-plants1 which bear directly on this subject4 ,all domestic animals and food-plants1 and many ornamental flowering plants1 have been subjected for ages to a process of artificial selection acting upon natural variation of offspring4 ,as wild species are modified1 we believe1 indefinitely by divergent variation and natural selection1 so domestic species are modifiable certainly largely1 perhaps indefinitely1 by divergent variation and artificial selection by man4 ,we all know the extraordinary modifications which have thus been gradually brought about in domestic animals1 such as dogs1 horses1 sheep1 pigeons1 etc42 in food-plants1 as cereal grains1 garden-vegetables1 etc41 and in ornamental plants1 as roses1 dahlias1 pinks1 etc4 ,we can only give very briefly the principles of the process by which these extreme modifications are produced1 referring the reader to works specially devoted to this subject for more complete accounts4 ,let it be borne in mind1 then 7a71 that inheritance is not only from the immediate parents1 but from the whole line of ancestry4 ,the inheritance from the immediate parents is1 doubtless1 usually greater than from any other one term of the ancestral series--the effect on the offspring of any previous generation becomes1 doubtless1 less and less as the distance from the offspring increases--yet the sum of the ancestral inheritance is far greater than the immediate parental4 ,let it also be borne in mind 7b7 that true breeding from one form for many generations creates a fund of heredity in that form1 and thus tends to produce fixity1 rigidity1 or permanence in that form4 ,illustration3 ,,fig4 #fh4 ,now1 the method of producing artificial breeds1 sometimes consciously1 sometimes unconsciously1 is1 briefly1 as follows3 ,suppose it be desired to obtain a variety of an animal1 say a dog1 having a certain character4 ,we start from a common type1 a 7,fig4 #fh74 ,if this type were allowed to breed naturally1 the slight divergent variation of offspring represented by the radiating lines would neutralize one another by interbreeding1 the individual differences would be 8pooled0 in a common stock1 and the species would remain substantially constant4 ,but if among all these slightly divergent varieties we select one1 b1 which seems in the right direction1 and ruthlessly destroy all the others 7indicated by crossing them out by the circular line71 and breed this variety1 b1 only1 we shall get again a number of divergent varieties4 ,it may be that the larger number of these will be backward1 in the direction of the original type a1 on account of the ancestral heredity in that direction1 but some will again be in the desired direction4 ,let all the varieties other than the desired one1 but especially the backward-going or reverting ones1 be again destroyed1 and the one kind only selected which seems to be in the right direction1 viz41 c4 ,as we push the form thus from generation to generation in the desired direction1 especially if we attempt to hasten too much the process1 the resistance to movement--if ,i may use the expression--in that direction becomes greater and greater 7shown by the decreasing distances between the successive points of divergence1 a1 b1 c1 d1 etc471 and the tendency to reversion becomes stronger 7shown by the greater number and length of the backward-going lines71 until finally it is almost impossible to push any farther4 ,we will suppose that x is such a limit4 ,but if1 now1 we breed true on the point x1 destroying the reversions or backward variations for many generations1 we will gradually accumulate a fund of ancestral heredity on this point which increases with every added generation1 until finally the tendency to reversion becomes small4 ,the variety breeds true without further interference1 or with only very general superintendence4 ,such a permanent variety is called a race4 ,after a race is firmly established for a sufficient length of time1 and the tendency to reversion is lost1 it may itself become a new point of departure for the formation of new varieties or races1 in the same or other directions4 ,thus1 during even the brief history of man1 have been formed races of the different domestic animals1 and useful and ornamental plants1 differing so greatly from each other that1 if found in the wild state1 they would unhesitatingly be called different species1 or even in some cases different genera4 ,now1 if art can vary form so greatly1 and in so short time1 why may not ,nature in limitless time8 ,if art by artificial selection1 why not ,nature by natural selection8 ,nature is as rigid in selection and as ruthless in destruction3 why may we not expect similar or even much greater results8 ,the process is similar in the two cases--i4 e41 selection among varieties in offspring1 only that the selection is natural instead of artificial1 and the process is so slow that there is little tendency to reversion in the latter case4 ,suppose1 then1 we have a gradually changing physical environment1 or climate4 ,among the divergent varieties of any species in each generation1 those would be preserved which are most in accordance with the new climate1 and the others would perish4 ,this is natural selection1 or survival of the fittest4 ,add to this the effect of the change in the organic environment4 ,all species are modified by the changing physical environment2 but these modified species again all affect one another in the competitive struggle for life1 and the strongest or swiftest1 or most cunning1 survive 7natural selection74 ,add to this1 again1 the struggle among the males for possession of the females--for reproductive opportunities--by which only the strongest and most courageous1 or the most beautiful and attractive1 leave progeny which inherit their peculiarities 7sexual selection74 ,add to these1 finally1 migrations1 voluntary among higher and involuntary dispersals among lower animals and plants1 and the consequent mingling of faunas and floras--the migrations subjecting them to great change of environment1 both physical and organic1 and the mingling producing fiercer struggle for life--and we have in powerful operation many causes of modification4 ,add1 ,i say1 all these causes of modification together1 and then make the process slow and continuous through unlimited time1 and where is the limit to the degree of change8 ,commencing in any species1 from any point of departure1 there are formed first slight modifications which would be called varieties2 then these modifications1 continuing in the same direction1 form races2 these races by wider separation become species1 and species in their turn become genera1 etc4 ,comparing1 again1 to a growing tree1 varieties are swelling buds2 when they grow into twigs1 they are species2 when they branch again into different species1 the branching stem becomes a genus1 etc4 ,we have thus far spoken only of the various forms of one factor1 viz41 the ,darwinian factor of selection1 whether natural or artificial4 ,we have dwelt upon this one1 because the natural and the artificial processes are so similar1 and the artificial is so controllable4 ,but there are other factors in operation1 in art as well as in nature4 ,we have already spoken 7p4 #gc7 of other factors of natural change4 ,we have shown how changing physical environment affects function1 and function affects form and structure1 and how these slight changes are integrated by heredity through many generations4 ,we have also shown how use or disuse increases or diminishes the size and change the form of parts1 and these changes1 also1 however slight1 are integrated by heredity4 ,now1 these factors are operative also in domestication of animals and cultivation of plants4 ,no environment is so new and peculiar as domestication and cultivation4 ,the soil and temperature in plants1 food and housing of domesticated animals1 tend to change form and structure of the offspring1 although in a way which it is difficult intelligently to control1 and thus are prolific of varieties from which to select4 ,in fact1 they often give rise to great and unexpected modifications1 called sports1 which form points of departure for new varieties and races4 ,now1 in nature1 not only are all these causes and factors of change in constant operation1 but they act together in a peculiarly complex way4 ,all the members of a fauna and flora1 and the physical environment of any locality1 constitute together a most complex and delicately adjusted system of correlated parts4 ,a change in one part is propagated through the whole system2 also1 a change in one factor affects all other factors4 ,when we add to this the large amount of time1 in comparison with individual human life and observation1 necessary to produce visible change of form1 we can easily understand why the process is still imperfectly understood1 although the fact is certain4 ,but it will be asked1 ,are there1 then1 no differences between the artificially made extreme varieties equivalent1 so far as difference of form is concerned1 to species1 and real natural species8 ,there are4 ,if there were not1 there would never have been any doubt about the derivative origin of natural species4 ,but if it be asked1 ,are not these differences fundamental1 and therefore fatal to the argument for evolution derived from this source8 we answer1 we think not4 ,we will deal frankly and fairly with these differences4 ,first ,difference1 ,reversion4--,the strong tendency of artificial varieties to reversion1 even during the process of formation1 and especially their complete reversion to the original type if the hand of man be withdrawn--i4 e41 if left to themselves1 or become wild--is supposed to show an essential difference between such varieties1 however extreme1 and true species--is supposed1 in fact1 to prove an indestructible permanency of specific types4 ,nature disowns these artificial forms1 and as it were brands them with bastardy4 ,not only so1 she strives ever to destroy them4 ,the supporting hand of man is necessary to sustain them4 ,left to themselves and to ,nature1 they quickly revert to the original type4 ,if all the extreme varieties of dogs1 from the greyhound and ,newfoundland1 on the one hand1 to the terrier and lap-dog on the other1 were turned loose on an isolated island1 uninhabited by man but full of other animals1 and left there to shift for themselves--and the island were visited again after a lapse of a hundred or a thousand years--it is probable that a uniform species1 something like to1 though perhaps not identical with1 the wolf1 would be found4 ,they would have reverted to the original or nearly the original wild type from which they were produced by domestication4 ,all or nearly all that was done by man would have been undone by ,nature4 ,this reversion is one test of species4 ,but the reason of this tendency to reversion is obvious3 ,first1 the time was too short1 the rate of change was too rapid1 in the artificial formation of these varieties4 ,there was not time enough to accumulate a fund of heredity on each successive stage of the change4 ,therefore the form is unstable and the tendency to revert is strong4 ,compare the fleeting days and the hurrying impatience of man with the infinite time and the divine patience of ,nature6 ,but mere instability is not the principal cause of reversion4 ,secondly1 in the case of artificial forms in a wild state1 natural selection compels reversion4 ,every species in a wild state must of course be in harmony with the environment4 ,but artificially made forms are in harmony with the artificial environment of domestication1 but not with the environment of nature4 ,in nature the fittest survive1 but artificial breeds are not fit to survive in a state of nature4 ,they are therefore quickly destroyed in the struggle for life1 or must be modified4 ,nature immediately begins to select the fittest1 and gradually in the course of time produces one or more uniform species1 similar to that from which they came1 or perhaps to what they would have been by this time if left to the operation of natural causes under the conditions supposed4 ,but natural species1 if they are formed1 as the derivationists suppose1 by the operation of natural causes1 can not revert unless the conditions revert2 for the same causes which operated to produce1 still continue to operate to keep1 the species4 ,take an example3 ,the form1 the habits1 and the instincts of the pointer have been made by a slow process of artificial selection of divergent varieties of offspring1 and by training of individuals continued and its effects accumulated through many generations4 ,but this form and these habits and instincts1 so laboriously produced1 would be quickly destroyed by ,nature4 ,the pointer1 left to himself1 must either change or become extinct1 because not adapted to the wild state4 ,such instincts and habits would not only be of no use1 but would be incompatible with success in the struggle for life4 ,but suppose for a moment that these habits and instincts were useful to the animal in a wild state2 evidently they would be instantly seized upon by natural selection1 and not only perpetuated but intensified until a very distinct species would be produced4 ,the same is true of all other races of dogs4 ,if the ,newfoundland1 the greyhound1 and the pug were all turned loose in a forest1 and if each of these kinds were admirably adapted to some place in the economy of ,nature--for some special mode of food-getting without corresponding disabilities in other directions 7as must be the case if made by natural selection7--there can be no doubt they would each survive1 and their characters intensified2 intermediate forms would disappear 7for reasons which we shall see presently71 and we would soon have three distinct species1 or perhaps we would even call them distinct genera4 ,second ,difference1 ,intermediate ,forms4--,natural species are distinct--marked out with hard and fast lines--while artificially-made races1 even though in their typical forms they differ as much or more than natural species1 shade into one another by insensible gradations4 ,in answer and explanation of this difference we remark3 ,if species or modified forms of any kind1 whether natural or artificial1 are made by natural causes1 and not at once out of hand by supernatural creation1 then of course there must have been gradations in the process of making4 ,now1 in the artificial case1 the whole process as well as the result lies within the limits of observation1 while in the natural case only the final result4 ,but it will be asked1 ,why are the gradations not seen also in the final result8 ,we answer1 because the intermediate forms are eliminated in the struggle for life1 and not reproduced by cross-breeding4 ,if artificial races always bred true--i4 e41 without crossing1 as natural species do--they would probably soon be as sharply demarked4 ,cross-breeding is the great cause of the shadings between domestic races4 ,this brings me to the third and most important difference4 ,third ,difference1 ,cross-,fertility4--,artificially-made races breed freely and without repugnance with one another1 and the offspring of such cross-breeding is indefinitely fertile4 ,natural species will not usually unite with one another1 being prevented by sexual repugnance and other causes4 ,or1 if they do sexually unite1 there is either no offspring1 or else the offspring is sterile1 and therefore the intermediate form dies out in the first generation2 or else the offspring is imperfectly fertile1 and therefore the intermediate form is eliminated in a few generations1 and the species remain distinct2 or else the offspring is more fertile with the parent stocks1 and therefore revert to the parent stocks1 and still the species remain distinct4 ,such infertile1 or imperfectly fertile1 offspring--the result of crossing of species--are called hybrids4 ,this is regarded as a most important test of true species1 as contrasted with varieties or races4 ,there are two bases on which species may be founded4 ,species may be based on form1 morphological species2 or they may be based on reproductive functions1 physiological species4 ,by the one method a certain amount of difference of form1 structure1 and habit1 constitutes species2 according to the other1 if the two kinds breed freely with each other and the offspring is indefinitely fertile1 the kinds are called varieties1 but if they do not they are called species4 ,the two tests1 however1 do not always accord4 ,every now and then we find undoubted morphological species which may be crossed and produce indefinitely fertile offspring4 ,yet it is certainly true that species are usually cross-sterile1 while varieties1 whether natural or artificial1 are cross-fertile4 ,in explanation of this important difference1 let it be observed that there are here two things which must be kept distinct in the mind1 although they are1 doubtless1 closely allied--viz41 sexual repugnance 7psychological element7 and cross-sterility 7physiological element74 ,the former is found1 of course1 only in the higher animals1 where fertilization is voluntary4 ,the latter is universal among all living things4 ,this latter1 therefore1 is the more fundamental and essential element1 and the former may be regarded as its psychical sign in the higher animals4 ,it is of this latter1 therefore--i4 e41 cross-sterility--that we shall speak mainly4 ,suppose1 then1 we have growing together in the same locality many species of pines or oaks1 or other anemophilous trees4 ,the whole air is filled with the pollen of many species1 and every germ-cell must receive many kinds of male cells1 and yet there are no hybrids1 but1 on the contrary1 the species remain distinct4 ,so also in case of hermaphrodite animals1 where the fertilization is involuntary2 many aquatic species are found together in the same locality1 and the water is filled with sperm-cells of many different species4 ,many kinds of sperm-cells must fall on each germ-cell1 and yet there are no hybrids2 the species remain distinct4 ,in all such cases we must suppose that there is1 among the different kinds of male cells1 a struggle for the possession of the germ or female cell1 or a sort of sexual selection by the female cell among the competing male cells1 and the fittest--the most in accord2 i4 e41 those of the same species--prevail4 ,this is universal4 ,but in the higher animals1 in addition to the prepotency of male cells of the same species1 and comparative infertility in case of union of those of different species1 sexual attraction and sexual repugnance contribute to the same result1 and species are thus doubly separated4 ,thus sexual selection is of two kinds3 selection of individuals for union 7psychical71 and selection of sperm-cells for fertilization 7physiological74 ,the one kind is usually the sign of the other--attraction the sign of fertility1 and repugnance of sterility4 ,but in the domestic state it is all otherwise4 ,free competition between individuals or between cells is not allowed4 ,thus1 for example1 among plants1 crossings may be forced and hybrids made in gardens which would never occur in ,nature4 ,the florist prevents fertilization in the same kind and compels fertilization of a different kind4 ,if male cells of the same kind were allowed to compete1 the result would be different4 ,doubtless the same method would succeed in many lower animals4 ,so also in higher animals free competition and sexual selection for union are often not allowed1 and therefore animals of different species1 such as the horse and the ass1 unite1 which would not do so if they were free to select as in the wild state4 ,these two are widely distinct species1 sometimes even called genera1 and therefore the offspring is infertile2 but two closely allied species1 such as two species of wolf1 or of the fox1 in a domestic state would probably not only unite but produce indefinitely fertile offspring4 ,in fact1 it is almost certain that the dog was made by a mixture of several species of wolf1 most1 perhaps all1 of them now extinct4#cj ,on the other hand1 it is not at all certain that the extreme varieties of dogs have not passed the limit of greatest attraction1 and therefore of greatest cross-fertility1 and that1 if allowed free choice1 as in ,nature1 they would not breed true1 or tend to breed true1 with their own kind1 and intermediate kinds die out in the struggle for life4 ,law of ,cross-breeding4--,before going any further in this discussion1 it is necessary to bring out another point of extreme importance in the formation of varieties1 both natural and artificial--a point which ,i believe throws light upon the very significance of sex itself--,i refer to the effect of cross-breeding4 ,it is a curious and most significant fact that different varieties1 both natural and artificial1 are1 up to a certain limit1 not only cross-fertile and cross-attractive1 but even more so than individuals of the same variety4 ,long experience has shown that very close breeding of the same variety for a long time fixes the kind but weakens the stock1 especially in fertility1 while judicious crossing of varieties strengthens the stock1 increasing its fertility1 and especially producing plasticity or variability4 ,therefore breeders1 if they wish to preserve a valuable variety1 breed close2 but1 if they wish to make new varieties1 cross-breed4 ,but we have already seen that species are usually cross-sterile4 ,therefore there must be some regular law of increase to a maximum1 and again decrease to zero4 ,it is this law that ,i now wish to investigate4 ,in the lowest animals and plants multiplication of individuals and the continuance of the kind are independent of sex1 and therefore in such there may be no sex at all4 ,the sexual elements are not yet differentiated4 ,an individual divides itself into two2 each grows to the original size and again divides into two1 and so on1 it may be indefinitely4 ,in this lowest form of reproduction the individual is sacrificed to the kind1 or else we may regard the kind as an extension of the individual1 and reproduction as a modification of growth4 ,but there are other sexless modes of reproduction1 found in nearly all plants and many lower animals1 in which the individuality is not sacrificed4 ,the next step in the ascending scale is reproduction by budding4 ,in this case a bud is formed which grows into a perfect individual1 and may remain attached to the parent stalk1 forming together a compound individual1 as in most plants and many lower animals1 such as the coral2 or it may separate and assume independent life1 as in some plants and many lower animals4 ,in still other animals1 as in many hydrozoa1 the budding function is relegated to a special part1 which thus becomes a reproductive organ4 ,the next step is the placing of the budding organ1 for greater safety1 in an interior cavity4 ,this is the case with aphids4 ,now1 why would not this be an excellent mode of reproduction for all animals1 man included8 ,why was sex introduced at all8 ,there are very sufficient reasons1 of many kinds1 which may come up later2 but the fundamental reason1 in connection with evolution1 is the funding of individual differences in a common offspring1 thereby giving to the offspring a tendency to divergent variation4 ,now1 non-sexual reproduction is absolute true breeding4 ,the law of like producing like is absolute4 ,heredity is all-powerful1 and tendency to variation is nil4 ,these modes of reproduction are in fact but a modification of growth and an extension of the individual4 ,evolution-changes in animals produced in this way only must be very slow1 since the most powerful factor of evolution1 viz41 natural selection among divergent varieties of offspring1 would be wanting4 ,in the earliest times1 therefore1 before sex was yet declared1 we may imagine that physical environment was the great and only factor of change4 ,sexual reproduction introduces the new element of variation of offspring from which ,nature makes her selections2 and this element of variation is apparently the result of the union of diverse individuals1 and the funding of these differences in a common offspring1 and thus a double inheritance of individual characteristics from the parents and a multiple inheritance of the same from the ancestry4 ,see1 then1 with this end in view1 the pains ,nature has taken to make the difference between the uniting individuals and the diversity of inheritance by the offspring as great as possible1 and yet the gradual way in which she has accomplished it4 ,as already said1 the lowest form of reproduction is that by fission4 ,next comes budding in any part indifferently4 ,next comes the relegation of the budding function to a particular part4 ,this is the first appearance of a reproductive organ4 ,next comes the placing of this organ1 for greater safety1 within4 ,thus far all is non-sexual reproduction--all a modification of growth--an extension of the individual1 like the propagation of plants by cuttings and by buds4 ,then comes sexual reproduction in its lowest forms4 ,it may be well to stop here1 to show the entire difference between this and non-sexual modes4 ,the latter1 we have seen1 is only a modification of growth1 an extension of the individual4 ,now1 sexual reproduction is the opposite of all this4 ,growth is a constant multiplication of cells4 ,one cell is ever becoming two similar cells--or1 if we call them individuals1 one individual is ever becoming two similar individuals4 ,but in sexual reproduction we have an exactly reverse process4 ,reduced to its simplest terms1 sexual reproduction is the fusion of two diverse cells1 sperm-cell and the germ-cell1 to form one cell1 the ovule--literally1 a diverse twain forming one flesh4 ,in its higher forms it is the union of diverse individuals to bring about the same result4 ,instead of one cell becoming two1 it is two cells becoming one2 instead of one individual becoming two in the offspring1 it is two individuals becoming one in the offspring4 ,but this great change was not brought about at once1 but only in the most gradual manner4 ,first1 the sexual elements--sperm-cell and germ-cell--are separated1 but in the same organ4 ,then the organs--spermary and ovary--are separated1 but in the same individual4 ,this is the condition of self-fertilizing hermaphroditism so common among plants and lower animals4 ,then comes cross-fertilizing hermaphroditism2 and ,nature takes much pains and uses many ingenious devices to prevent self-fertilization and insure cross-fertilization4 ,now1 for the first time1 we have slight individual differences funded in a common offspring4 ,then1 in order to absolutely forbid self-fertilization1 and at the same time allow greater differences in the crossing individuals than could be attained in hermaphroditic individuals1 the sex organs are separated in different individuals1 and fertilization can only take place by voluntary union4 ,then1 to insure the union of suitable individuals1 and forbid the ban between unsuitable1 there are introduced sexual attraction and repulsion4 ,then1 last of all1 the difference between the two sex-individuals becomes greater and greater as we go up4 ,it is conspicuous only in vertebrates and some insects1 and very conspicuous only in birds and mammals4 ,we see1 then1 as we go up the taxonomic1 and undoubtedly also the phylogenic series1 that there is a cross-breeding of more and more diverse individuals1 a funding of more and more divergent characteristics in a common offspring4 ,why is this8 ,i answer1 for the sake of better results in the offspring4 ,this is abundantly shown by direct experiment4 ,in hermaphroditic plants in which there may be either self-fertilization or else cross-fertilization with other individuals of the same species1 the latter produces better results in number and vigor of offspring4 ,but there are other advantages1 more difficult to prove but none the less certain1 and of the greatest importance in evolution3 ,first1 as already stated1 complexity of inheritance1 like complexity of composition in a chemical substance1 gives instability to the embryo1 and thus liability to variation in the offspring2 and this in its turn furnishes the material for selection of the fittest4 ,again1 it seems to me that there is a direct tendency to improve the offspring by a sort of struggle in the embryo among the various qualities inherited from both sides1 and a survival of the best and strongest--a sort of pre-potency of strong qualities4 ,can divergence of uniting individuals and the funding of diverse characteristics go any further8 ,it may4 ,the differences of the uniting individual may be still further increased1 and the resulting offspring still further improved by the cross-breeding of different varieties of the same species1 for we thus add varietal differences to sexual differences in the uniting individuals4 ,it is well known that too close breeding1 or consanguineous breeding1 or breeding in and in1 as it is variously called1 if continued long1 has a bad effect on the offspring1 weakening the stock1 while judicious crossing of varieties within certain limits of difference has a good effect1 strengthening the stock and increasing its fertility4 ,it probably does so in two ways3 one direct1 by funding many diverse qualities from both sides1 and the survival in the offspring of the strongest and best2 the other indirect1 by giving plasticity1 instability to the embryo1 and variability to the offspring1 and therefore abundant material for the operation of selection1 either by man or by ,nature4 ,we said1 8within certain limits of difference40 ,if the difference is extreme1 as in extreme varieties and races1 then the effect becomes again bad1 and more and more so as the limit of specific difference is approached2 at which limit at last ,nature shuts down and forbids the bans4 ,thus1 then1 there is in cross-breeding a regular law of effect1 increasing to a maximum and again decreasing1 which may be graphically represented by a curve 7,fig4 #fi74 ,in this figure the horizontal line represents the ordinary level of the type2 distances on this line represent differences1 individual1 varietal1 or specific2 ordinates above or below represent the effect1 good or bad1 of crossing4 ,thus s s represent two species1 and the line between represents their specific differences2 r r represent different races or permanent varieties2 v v two strong varieties2 d d ordinary individual differences2 c c close resembling or consanguineous individuals4 ,the undulating line represents the effect of crossing these various kinds4 ,it is seen that 8in-and-in breeding10 c c1 produces bad effect 7negative ordinates72 breeding of ordinary individual differences1 d d1 keeps the stock at the ordinary level--in its typical form2 crossing two strong varieties1 v v1 produces maximum good effect 7positive ordinates72 crossing decided races produces again bad effects1 which become infinitely bad as we approach species1 ,s ,s4#ca ,illustration3 ,,fig4 #fi4 ,it is generally admitted that long-continued very close breeding has a bad effect4 ,even in plants1 ,darwin has shown that cross-fertilization has better effect than self-fertilization1 this last being of course the closest possible breeding4 ,but it is probable that the principal bad effect is not on the stock but on the process of evolution4 ,very close breeding weakens the stock1 ordinary breeding of individual differences maintains the stock at the ordinary level and fixes it4 ,cross-breeding of varieties strengthens the stock1 and also 7and this is its main advantage7 produces plasticity in the stock1 gives rise to strong divergent variations1 or even sports1 and thus becomes a main agent in evolution4 ,it is probable1 moreover1 that the higher the function the more sensitive is it to these effects of breeding4 ,therefore1 the effect is greater in man than in any other animal4 ,it is true that many have doubted the bad effect of close breeding in man1 and have brought forward formidable statistics to substantiate their position2 but these doubtless take no account of the most important function1 the psychic1 and especially the most important element in every function1 so far as evolution or progress is concerned1 viz41 plasticity or capability of progressive improvement4 ,the tendency of consanguineous breeding1 or even the breeding of persons of like character and experiences1 as in an isolated community1 is1 if not to deteriorate the physique1 at least to fix1 stereotype the character1 and thus to check social progress4 ,contrarily1 the crossing of varieties of the same race seems not only to strengthen but1 by the diverse inheritance1 to produce plasticity of character and capacity for progress4 ,but the difference between the primary races seems too great for crossing with advantage4 ,some degree of sexual repugnance which undoubtedly exists between the primary races is the psychical sign of this fact4#cb ,if1 now1 we go back to what we said before taking up this subject of the effect of cross-breeding1 we at once see that there is an apparent flaw in all our reasonings4 ,if close in-and-in breeding produced better and more numerous offspring than cross-breeding between slight varieties1 then1 indeed1 such varieties would be preserved1 and increase in divergence from generation to generation until they became species4 ,or1 in any case1 if1 in any way1 divergence could reach the point of extreme varieties or races1 or what are called sub-species1 then commencing cross-sterility would complete the separation1 and thus form true species4 ,but how can the process of progressive divergence begin1 when slight varieties are even more fertile by cross-breeding than by close breeding8 ,is it not evident that1 with every generation1 the slight varieties would cross-breed with one another and with the parent stock1 and thus all varietal differences would be funded into a common stock1 and the type would be preserved unchanged8 ,this1 as already pointed out 7p4 #gf71 has always been the chief difficulty in the way of imagining how varieties can grow into species2 and the difficulty is only increased by our discussion of the law of cross-breeding4 ,now1 just here1 ,dr4 ,romanes's most important and prolific idea comes to our help1 and1 as it seems to us1 completely solves the difficulty4 ,according to ,dr4 ,romanes1 no organ is so subject to variation as the reproductive1 and this in no respect so much as in degrees and kinds of fertility--we might almost say so subject to freaks of cross-sterility4 ,now1 suppose we start with any well-defined species in a state of nature4 ,with every generation there are many slightly divergent individual varieties1 some greater and some less2 but these are all immediately swamped by crossing with one another and with the parent stock1 and the species remains unchanged4 ,but suppose among these divergent variations there arise1 from time to time1 some which affect the reproductive organs in such wise that the variety1 though perfectly fertile with its own kind1 is infertile1 or imperfectly fertile1 with other varieties1 and especially with the parent stock4 ,the change may be only in the time of flowering in plants1 or season of heat in animals1 or it may be actual infertility in sexual union4 ,right here we have the beginning of a new species4 ,the variety is sexually isolated from the parent stock by cross-sterility1 and therefore all its peculiarities1 however trivial1 are preserved by true breeding4 ,cross-breeding is necessary to make species1 but true breeding preserves them4 ,cross-breeding tends ever to make varieties1 but immediately destroys them again4 ,this constant forming and swamping1 separating and again merging of varieties1 like mixing of dough1 makes the whole mass 7stock7 more and more plastic and subject to variety4 ,this plasticity finally gives rise to varieties of the kind which produces species by sexual isolation4 ,by continued merging the centrifugal forces continually increase1 but are continually repressed by crossing1 until finally varieties break away to form species4 ,now it is easy to see1 from this point of view1 why artificial varieties are cross-fertile4 ,it is because in artificial breeding we are intent only on making varieties in form1 size1 color1 etc41 and not at all on making any characterized by cross-sterility with the parent stock4 ,cross-sterility with the parent stock1 or with other varieties1 would be of no advantage1 because we control the breeding1 and can breed true if we desire4 ,sexual isolation is not necessary1 because we can use physical isolation4 ,on the contrary1 such cross-sterility would be a positive disadvantage to the breeder1 by limiting the range of his experiments just where they would be most prolific in making new varieties4 ,hence1 as might be expected1 all domestic varieties are cross-fertile1 unless it be the extreme varieties1 which may1 in some instances1 have passed the limit of greatest fertility4 ,if this idea be true1 then species which have originated in the same locality ought to be always cross-sterile1 but species which have grown up apart1 in widely separated geographical regions1 ought to be sometimes cross-fertile1 because they were isolated by physical not by sexual barriers4 ,such1 ,dr4 ,romanes thinks1 is a fact4 ,it is1 however1 a very important point1 which ought to be carefully investigated4 ,we say 8sometimes40 ,it is probable that most geographical species also are cross-sterile2 for1 although the isolation by cross-sterility of slight varieties be the main cause of the origin of species1 yet a species formed by isolation of any other kind will gradually become cross-sterile with other species4 ,although cross-sterility be the main cause of divergence1 yet divergence beyond a certain limit1 however caused1 will bring about cross-sterility1 because the reproductive organs will partake of the general change going on in every part4 ,application4--,suppose1 then1 a species breeding naturally in a wild state4 ,individual varieties are constantly being formed and again funded back into the common stock by cross-breeding4 ,if the varieties thus formed be decided1 the cross-breeding will strengthen the stock1 and especially will preserve and increase its plasticity or tendency to variation4 ,finally1 among the widely divergent varieties there is one affecting the reproductive organs of several individuals in such wise that they are infertile1 or imperfectly fertile1 with the parent stock1 though perfectly fertile among themselves4 ,these form a new species1 which continue to increase indefinitely4 ,objection answered4--,this view completes the answer to an objection which is often made to evolution3 8,if natural species are formed by transmutation1 why is it we do not find intermediate links8 ,why is not organic nature made up only of individual forms1 shading insensibly into each other in such wise that classification becomes a mere device to handle more conveniently complex material8 ,why is it that groups1 especially species1 are marked out with hard and fast lines80 ,we have heretofore answered this by saying that intermediate forms are eliminated4 ,so they are1 but how8 ,dr4 ,romanes's idea of physiological selection largely answers this4 ,it is by the funding of ordinary varieties into a common parental stock by crossing1 and separating specific varieties by cross-sterility4 ,thus the organic field is broken up into points about which variations oscillate4 ,as every mass of matter1 when closely examined1 is found to consist of aggregations about centers of cohesive attraction as discrete granules or crystals1 and only exceptionally do we find a homogeneous vitreous structure2 even so organic forms aggregate about points of sexual attraction1 and the whole mass consists of discrete species1 and only exceptionally--i4 e41 in domestication--do we find insensible shadings4 ,now1 species are the smallest aggregate of individuals1 as granules are of molecules4 ,species are more distinctly marked out by hard and fast lines than are other taxonomic groups only because they are the last1 going downward1 that are cross-sterile--because right here is the change from cross-sterility to cross-fertility4 ,if this view be true1 then in the same locality species ought to be always distinct and without shadings4 ,if we find shadings at all1 it ought to be in intermediate geographical regions1 where isolation is not sexual but physical4 ,now1 this is exactly what we find to be the fact4 ,innumerable examples of such intermediate forms in intermediate geographical regions are now known1 especially among birds and reptiles1 and examples have so increased in modern times1 by closer study1 that naturalists1 especially ornithologists1 have been compelled to resort to a trinomial nomenclature in order to designate these geographical sub-species4#cc ,if any further explanation is necessary1 it will probably be found in the following suggestions3 #a4 ,the number of individual varieties constantly being formed is almost infinite1 but the number of places in nature is very limited4 ,now1 among the infinite number of slight individual varieties formed with every generation1 the competitive struggle will be severest between those most nearly alike1 because they are competitors for the same place4 ,only one kind succeeds1 viz41 the fittest4 ,intermediate forms are1 therefore1 exactly those which are eliminated in the most wholesale way4 #b4 ,add to this the fact that1 as soon as divergence1 from whatsoever cause1 reaches a certain point1 sexual repugnance or cross-sterility1 or both1 come in to perpetuate and increase the separation already commenced4 #c4 ,add to this1 again1 that migrations in higher animals1 and involuntary dispersals in lower animals and in plants1 and the mingling together of different faunas and floras1 produces a still fiercer struggle for life1 especially between natives and invaders1 and thus great numbers of forms are destroyed2 all but the fittest are weeded out1 and therefore the distinctness of the remainder is greatly increased4 ,periods of great changes of physical geography and of climate1 and therefore of wide and general migrations1 are also periods of great weedings-out of unfit forms4 ,thus it happens that existing faunas and floras are little else than isolated remnants4 ,to illustrate1 again1 by a growing tree3 ,if all the buds of a tree lived and grew1 they would soon become so numerous that they would together form a solid hemispherical mass1 like a coral-head1 with no room between for leaf or light or air4 ,but ninety-nine one-hundredths of buds die in the struggle for light and air1 and therefore the survivors are distinct growing points1 widely separated from each other4 ,species are such extreme1 but separated1 twiglets of the tree of life4 ,objection4--,but it will be objected1 again3 ,the twig-points are1 indeed1 separate1 but the twigs themselves must meet somewhere lower down1 where they began to grow4 ,intermediate links may be wanting now1 but they must1 of course1 have existed once--i4 e41 in previous geological times1 and therefore ought to be found fossil4 ,in distribution in space or geographically1 organic kinds may be marked off by hard-and-fast lines1 but1 if their derivative origin be true1 in their distribution in time or geologically1 there ought to be many examples of insensible shadings between them4 ,in fact1 if we only had all the extinct forms1 the organic kingdom1 taken as a whole and throughout all time1 ought to consist not of species at all1 but simply of individual forms1 shading insensibly into each other1 like the colors of the spectrum1 and our classification ought to be a mere matter of convenience1 having no counterpart in nature4 ,but this is not the fact4 ,on the contrary1 the law of distribution in time is apparently similar in this respect to the law of distribution in space1 already given 7page #afi74 ,as in the case of contiguous geographical faunas1 the change is apparently by substitution of one species for another1 and not by transmutation of one species into another4 ,so also in successive geological faunas1 the change seems rather by substitution than by transmutation4 ,in both cases species seem to come in suddenly1 with all their specific characters perfect1 remain substantially unchanged as long as they last1 and then die out and are replaced by others4 ,certainly this looks much like immutability of specific forms1 and supernaturalism of specific origin4 ,we have1 we believe1 satisfactorily explained this in the case of geographical distribution 7page #bja71 but how can we explain it in the case of geological distribution8 ,answer4--#a4 ,the reason for this1 given by ,darwin and other evolutionists1 is the extremely fragmentary character of the geological record4 ,if the existing faunas and floras are but isolated remnants1 the rest having been destroyed by migrations and conflicts1 how much more are fossil faunas and floras but fragmentary remnants1 the rest having been lost1 partly because never preserved1 and partly by destruction of the record6 ,if from this cause existing species are widely separated1 how much more ought we to expect to find fossil species distinct and widely separated6 ,this is undoubtedly in most cases a true and sufficient answer1 yet we think the fragmentariness of the geological record has been overstated4 ,while it is true that there are many and wide gaps in the record2 while it is true1 also1 that even where the record is continuous many forms may not have been preserved1 yet there are some cases1 especially in the ,tertiary fresh-water deposits1 where the record is not only continuous for hundreds of feet in thickness1 but the abundance of life was very great1 and the conditions necessary for preservation exceptionally good4 ,in such cases the number of fossil species found on each horizon seems to be as great as in existing faunas over equal space4 ,the record in these cases seems to be continuous and without break1 and crowded with fossil forms2 and yet1 although the species change greatly1 and perhaps many times1 in passing from the lowest to the highest strata1 we do not usually1 it must be acknowledged1 find the gradual transitions we would naturally expect1 if the change were effected by gradual transformations4 ,the incompleteness of the record1 therefore1 although a true and important cause1 is not the whole cause4 ,in further and completer answer to this greatest of all objections1 we will throw out the following suggestions3 #b4 ,we must remember that considerable latitude is allowed by the anti-derivationists to variation of species2 so much so1 indeed1 that it is often difficult to draw the line between well-marked varieties and closely-allied species4 ,now1 according to the derivationist1 these strong varieties1 breeding usually true1 are naught else than commencing species4 #c4 ,on every side and everywhere1 both in existing faunas and in fossil forms1 but especially in the latter1 we find innumerable examples of transitions1 or intermediate forms1 between all the higher groups1 such as genera1 families1 orders1 and classes4 ,it is1 in fact1 by means of these that the great law of differentiation from generalized types has been established4 ,it is1 therefore1 only between species that such intermediate forms are rare4 #d4 ,but even between species such intermediate forms1 though rare1 have been pointed out1 both in existing and in extinct faunas4 ,but the opposition contend that1 in all such cases1 the previously supposed species are only varieties4 ,we have already 7page #fa7 spoken of the obvious fallacy involved in this position4 ,species are first defined as forms distinct and without intermediate links1 and then we are challenged to find such links2 and when1 with much labor1 we find them1 they say the supposed species are not species1 but only varieties4 ,but there are some cases in which this subterfuge will not do4 ,there are cases in which the transitions are between forms so extreme that they can not1 by any stretch of the term1 be called varieties4 ,we will select and dwell upon but one striking example1 viz41 the fossil forms of the ,tertiary fresh-water deposits of ,steinheim4 ,in ,wrtemberg1 near the little village of ,steinheim1 are found certain strata of sand and lime1 which are evidently deposits from a small lake of ,tertiary times4 ,the deposits are extremely rich in fossil shells1 especially of the different species of the genus ,planorbis4 ,as the deposits seem to have been continuous for ages1 and the fossil shells very abundant1 this seemed to be an excellent opportunity to test the theory of derivation4 ,with this end in view1 they have been made the subject of exhaustive study by ,hilgendorf in #ahff1cd and by ,hyatt in #ahhj4ce ,in passing from the lowest to the highest strata the species change greatly and many times1 the extreme forms being so different that were it not for the intermediate forms they would be called not only different species but different genera4 ,and yet the gradations are so insensible that the whole series is nothing less than a demonstration1 in this case at least1 of origin of species by derivation with modifications4 ,the accompanying plate of successive forms 7,fig4 #gj71 which we take from ,prof4 ,hyatt's admirable memoir1 will show this better than any mere verbal explanation4 ,it will be observed that1 commencing with four slight varieties--probably sexually isolated varieties--of one species1 each series shows a gradual transformation as we go upward in the strata--i4 e41 onward in time4 ,series ,i branches into three sub-series1 in two of which the change of form is extreme4 ,series ,,iv is remarkable for great increase in size as well as change in form4 ,in the plate we give only selected stages1 but in the fuller plates of the memoir1 and still more in the shells themselves1 the subtilest gradations are found4 ,illustration3 ,,fig4 #gj4--,transformations of ,planorbis 7after ,hyatt74 ,series ,,iv4 #a1 ,pl4 levis3 ,undorf4 #b1 ,pl4 ,steinheimensis2 #c1 tenuis-,steinheimensis2 #d1 tenuis2 #e1 discoideus2 #f1 trochiformis-discoideus2 #g1 trochiformis3 ,steinheim4 ,series ,,iii4 #h1 ,pl4 levis3 ,undorf4 #i1 ,pl4 oxystomus2 #aj1 supremus2 #aa1 supremus var4 turrita3 ,steinheim4 ,series ,,ii4 #ab1 ,pl4 levis3 ,undorf4 #ac1 ,pl4 crescens-parvus2 #ad1 #ae1 crescens3 ,steinheim4 ,series ,i4 ,sub-series #c4 #af1 ,pl4 levis3 ,undorf4 #ag1 ,pl4 minutus-levis2 #ah1 minutus2 #ai1 #bj1 triquetrus3 ,steinheim4 ,sub-series #b4 #ba1 ,pl4 minutus2 #bb1 #bc1 denudatus-minutus2 #bd1 denudatus var4 distortus3 ,steinheim4 ,sub-series #a4 #be1 ,pl4 costatus-minutus2 #bf1 costatus2 #bg1 #bh1 costatus var--3 ,steinheim4 ,the specimens from ,undorf all belong to an older ,tertiary period than that at ,steinheim4 ,this case is striking1 partly because it is a very favorable one1 but mainly because it has been so carefully studied4 ,there can be no doubt that equally careful study would reveal the same transition in many other cases4 ,nor are such transitions confined to the lower forms of life1 though they are probably more abundant there4 ,according to ,cope1 the nicest gradations may be traced between some of the extinct mammalian species so abundant in the ,tertiary deposits of the ,west--especially between the species of the extinct generalized family of ,oredontid#cf ,the same is probably true of the many extinct species of the horse family4 ,it is interesting to observe that the details of the process of change in the forms of ,planorbis are in accord with ,dr4 ,romanes's views4 ,the change does not seem to have been uniform but somewhat paroxysmal4 ,the forms seem to remain stable for a long time1 and then a few break into several different forms1 while the more rigid die out4 ,it is as if cross-breeding had kept the type true1 but at the same time increased its tendency to variation1 until finally one or more varieties became sexually isolated and thus formed new species4 #e4 ,but still the question remains3 ,why are transitional forms rare in all cases1 especially between species--so rare that they are eagerly sought and highly prized8 ,i believe that the true reason of this is that the steps of evolution are not always uniform4 ,nearly all evolutionists have assumed and even insisted on uniformity1 as the opposite of catastrophism and of supernaturalism1 and therefore as essential to the idea of evolution4 ,they say that the constancy of the action of the forces of change necessitates the uniformity of the rate of change4 ,but1 in fact1 this is not always nor even usually true4 ,causes or forces are constant1 but phenomena everywhere and in every department of ,nature are paroxysmal4 ,the forces producing storms and lightning1 and volcanoes and earthquakes1 are or may be constant2 yet the phenomena are in the highest degree paroxysmal4 ,wherever in nature we have a constant force and a strong resistance1 we find more or less paroxysmal action4 ,for this reason the wind blows in puffs1 the friction of wind on water produces waves1 water running in small pipes issues in pulses4 ,the reason is obvious1 as may be seen by the following examples3 ,suppose lifting forces within the earth are resisted by crust-rigidity4 ,the forces accumulate uniformly until the resistance gives way1 and suddenly we have an earthquake4 ,water running with great resistance in small pipes is checked1 but soon accumulates additional force1 which overcomes the resistance1 only to be again checked1 and so on1 and therefore runs in pulses4 ,now1 the course of evolution of the whole earth may be likened to such a current2 there are forces of movement and forces of resistance--progressive forces and conservative forces4 ,the progressive force is accumulative1 the resisting force is constant4 ,thus1 in all evolution or history1 whether of the earth or of society1 there are periods of comparative quiet1 during which the forces of change are gathering strength1 and periods of revolution or rapid change1 during which these forces show themselves in conspicuous effects4 ,now1 that there have been such periods of rapid revolutionary change in the history of the earth1 there can be no doubt4 ,the history of the earth is marked by periods of comparative quiet1 during which life was exceptionally abundant and prosperous1 and change of organic forms slow and uniform--separated by periods of disturbance1 revolution1 rapid changes of physical geography and climate1 and consequently of comparatively rapid and sweeping changes in organic forms4 ,these form the division-lines between great eras of the earth's history1 and are always marked by extensive unconformity of the strata1 showing the changes of physical geography above spoken of1 and by apparently sudden and sweeping change in life-forms1 showing the great changes of climate and other physical conditions4 ,unfortunately1 in all cases of unconformity of strata1 there is1 of course1 a break in the continuity of the record2 and when the unconformity is very general a portion of the record may be irrecoverably lost4 ,the consequence is1 that there is an apparent break also in the continuity of life-forms4 ,it looks1 at first sight1 like wholesale extermination of old and recreation of new forms4 ,but undoubtedly the break in the continuity of life is apparent only1 as is shown by the loss in the record4 ,if we could recover the whole record1 as indeed we sometimes do1 we should find in all cases that there is no break in the continuity of evolution1 but only more rapid rate of change at these times4 ,but to this cause of rapid rate of progress--i4 e41 change of physical environment--we must add change of organic environment induced by the physical4 ,we have already seen 7p4 #agi7 that extensive changes in physical geography and climate are always accompanied by wide migrations and dispersals of species1 the mingling of faunas and floras1 and the severer struggle for life1 and the sweeping weeding-out of all but the fittest1 and the change of these latter1 making them still fitter4 ,these two causes of rapid change1 viz41 change of climate and migrations1 together with the loss of record1 we believe completely account for those sweeping changes1 not only of species but even of genera1 families1 and orders which characterize the passage from one great era to another4 ,but this does not yet explain the apparent discontinuity between consecutive species in the same locality in continuous1 conformable strata1 or the rarity of transitional forms when one species takes the place of another in an apparently continuous record4 ,in such continuous deposits the successive faunas do indeed gradate insensibly into one another1 but apparently as in contiguous geographical regions 7p4 #bjj7 by substitution1 not by transmutation4 ,how shall we explain this8 ,on this point ,i throw out some suggestions3 #a4 ,in the modification of species1 too1 as well as in other progressive changes1 we may imagine two forces operating1 one progressive1 the other conservative--the one external1 the other internal4 ,the external progressive force consists of all the factors of change already mentioned1 the internal conservative is the law of heredity1 of like producing like4 ,a changing environment tends continually and increasingly to change of organisms1 but change is resisted by heredity1 which tends to adhere1 within narrow limits1 to the same form4 ,but since the external force or tendency to change increases constantly--since the discord between the environment and the organism becomes ever greater1 there must come a time when either the species is destroyed1 or else the resistance of heredity gives way1 and rapid change takes place4 ,the alternative is presented to the species to transform or perish2 and in one or perhaps in two or three generations we have an amount of change which1 under other circumstances1 might take a hundred generations to accomplish4 ,these rapid changes are in fact exactly what in artificial varieties we call sports4 ,we do not know all the conditions which determine sports in domestication1 and still less what determines large and widely-divergent variations1 and therefore rapid origin of many divergent species1 in geological history4 ,but one thing seems probable1 viz41 that1 when a species begins to change1 it continues to change easily and in many directions4 ,when resistance gives way it takes some time1 many generations1 for heredity to gather force again4 ,hence1 young species are plastic1 fluent1 because heredity1 on any one point1 has not yet accumulated4 ,but as soon as a stable form is again reached1 then1 by accumulating a fund of heredity1 the form tends to become more and more rigid1 until often it becomes too rigid to yield to modifying influences1 and therefore becomes extinct4 ,by far the greater number of species do thus become extinct and leave no progeny1 while the few more plastic forms are modified in several directions1 and the number of forms may1 after a little time1 be undiminished or even increased4 #b4 ,as to the cause of rapid changes of form during revolutionary or critical periods in the earth's history1 ,brooks has introduced an idea which is very suggestive1 and deserves serious attention4 ,we have above spoken of the progressive element as external4 ,brooks regards both elements as internal1 and represented by the two sexes4 ,the male represents the progressive1 the female the conservative element4 ,the one tends to divergent variation1 the other to fixity of type by heredity4 ,i think we will all admit that1 as a general rule1 in man 7and probably all the higher animals7 the male is more highly differentiated into many divergent forms--the female is more like the type-form of the species4 ,in man1 the male is certainly more diversified in form1 in expression1 and in character4 ,if they have the keenest ear for musical pitch1 they are also most often music-deaf2 if they have the sharpest perception of color1 they are also most often color-blind2 if among them we find the brightest intellects1 we also find the dullest and most stupid2 if there are among them more geniuses1 so1 also1 there are more cranks4 ,the same is also1 probably1 true of other animals1 in proportion to their grade of organization4 ,the operation of these two equally necessary elements is well shown in every advancing society4 ,the initiative of every movement1 in all directions1 good or bad1 is determined by the male2 the conservation of whatever balance of good there may be1 seems to be mainly by the female4 ,the male tries all things1 the female holds fast that which is good4 ,by the one society gains a little in each generation2 by the other the gain is conserved and made a new point of departure4 ,the one is ever building hastily a scaffolding and platform2 the other ever consolidating into a permanent structure4 ,now1 according to ,brooks1 what is true in the plane of social progress is true also in the lower plane of organic evolution4 ,in sexual union1 and in the resulting offspring1 the sperm-cell is the element which tends to divergent variation1 and the germ-cell to fixity of type1 through heredity4 ,in artificial breeding1 then1 we ought to make new varieties by proper use of the sire2 we ought to preserve them true by proper management of the dam4 ,but1 again1 it is believed that in many lower animals1 especially insects1 the high-feeding of the mother1 and consequent good condition of the ovum1 tends to the production of female offspring4 ,it seems almost certain that1 in butterflies1 the sex is not yet declared in the caterpillar stage4 ,according to the careful experiments of ,mrs4 ,treat1#cg if the caterpillars be well fed1 they become female butterflies2 but1 if poorly fed1 they make males4 ,one purpose of this provision of ,nature is1 doubtless1 to provide for the greater draught on the vitality of the female in reproduction4 ,now for the application4 ,in good times in the history of a species1 when everything is prosperous1 external conditions are favorable1 and food is abundant1 females are in excess1 and individuals are greatly multiplied4 ,under these conditions1 evolution would be slow and uniform4 ,but in bad times in the history of a species1 when external conditions were unfavorable1 not only would there be excess of males1 but these1 through the influence of the changing environment1 as well as through the dominance of the male element1 would be more than usually varied in character4 ,among the strongly divergent varieties thus formed1 the fittest--i4 e41 those most in accord with the changing environment--would survive and leave offspring partaking of their character4 ,we have already repeatedly said that the severer pressure of a rapidly-changing environment determines correspondingly rapid changes in organic forms4 ,it may do so in many ways2 but1 according to ,brooks1 one of the most important ways is by determining an excess of the male element4 ,in brief1 then1 the causes of rarity of transitional forms among fossils are--#a4 ,the change being1 for the reasons given1 comparatively rapid1 the number of generations between consecutive species are few1 perhaps only one4 #b4 ,times of rapid change are also times of unfavorable conditions1 and therefore the number of individuals in each generation is small1 and all the smaller--in ,brooks's view--because of the fewness of females4 ,when we remember that fossils are but a small fraction of the actual faunas and floras of the time1 surely these two causes go far toward explaining the rarity of links between species4 #c4 ,add to these the existence of periods of wide-spread changes in physical geography and climate1 and consequent wide migrations and dispersals of species1 and we sufficiently account for those sweeping changes in species1 genera1 families1 and orders1 which mark the limits of the great eras1 and which are made still more abrupt1 and apparently supernatural1 by the loss of record at these times4#ch ,objection4--,there is still one more objection which will be made4 ,we have drawings of plants1 animals1 and men1 by ,egyptian artists1 who lived at least three thousand years ago1 and the species of the one and the races of the other are still the same4 ,still better1 we have among the wrappings of ,egyptian mummies the very plants themselves1 leaves and flowers perfectly preserved1 and even colors almost perfect4 ,yet the species are exactly the same as grow in ,egypt to-day4 ,if species are made by gradual transmutation1 surely there ought to have been some change in three thousand years4 ,answer4--,it may be well to note that this apparent permanence is true of races of men as well as of species of animals and plants4 ,but the very men who insist on permanence of species are equally insistent on the variability of varieties and races4 ,the objection1 therefore1 proves too much4 ,we shall not insist on this1 however1 because as derivationists we regard races as naught else than commencing species1 and therefore subject to the same laws4 ,we are not striving for triumph in debate1 but only for truth4 ,the true answer will1 we believe1 be found among the following suggestions3 #a4 ,three thousand years seems a long time in human history1 but in geological history it is but a day4 ,this1 the usual answer1 is no doubt a true one1 but hardly1 we think1 sufficient4 ,when we remember the enormous change which has taken place in faunas and floras since the end of the ,tertiary1 if change still continues at the same rate1 surely it ought to be distinctly perceptible in three thousand years4 #b4 ,but we must remember that such changes are usually more or less paroxysmal2 not1 indeed1 so sudden as to break the continuity of life1 but far more rapid at some times than at others4 ,the last critical or revolutionary period of rapid change was the ,glacial epoch4 ,since that time--i4 e41 during the human period--a new equilibrium has been established1 and the changes in organic forms have been very slow4 #c4 ,remember1 again1 that in evolution all species do not change4 ,on the contrary1 most become rigid1 and either remain unchanged1 almost indefinitely1 or else die out and leave no descendants4 ,only the more plastic forms change into other species1 but usually into several other species1 and thus the number of forms may be undiminished1 even though the larger number of old forms leave no descendants4 ,it is true1 therefore1 of this as well as of other epochs1 that the greater number of species are permanent4 #d4 ,it is not impossible--indeed1 it is in exact accordance with the laws of evolution--that organic forms are more permanent now than ever before4 ,evolution is a growth2 the forces of growth must exhaust themselves4 ,evolution proceeds by constant differentiation and specialization1 but extreme specialization always arrests evolution4 ,in ontogenic evolution1 for example1 cell-structure becomes more and more specialized1 but also thereby more and more rigid1 and1 when specialization is complete1 evolution stops1 and cell-forms are permanent4 ,it is this which limits the cycle of every evolution4 ,so is it precisely with evolution of the organic kingdom1 except that the cycle is much longer4 ,here1 also1 every step is by specialization1 and yet specialization fixes the form1 and finally arrests the advance on that line4 ,thus1 throughout the whole geological history of the earth1 the larger number of forms1 by specialization1 become rigid and perish1 while the fewer1 more generalized1 and more plastic forms take up the march and carry it forward a step1 only to be themselves specialized and fixed4 ,if we compare1 again1 to a tree3 each twig finishes its growth1 flowers1 fruits1 and dies2 other buds take up the growth and carry it forward4 ,by specialization the highest condition of a certain form of life is attained1 but other possibilities are shut off4 ,extreme specialization is the flowering and fruiting--the end and completion of twig-life4 ,now1 obviously1 this specialization and respecialization can not go on forever4 ,when it is complete in every direction it must cease1 and forms become permanent1 or else perish4 ,when it flowers it must die4 ,now1 is not the advent of man in many ways a sign of the completeness of organic evolution8 ,certain it is that with man there begins an entirely new form of evolution4 ,certain it is that with man evolution is transferred from the organic to the social plane1 from the material to the psychical4 ,certain it is that the forces1 the conditions and results of this evolution1 are wholly different from those of the other4 ,in organic evolution the organism must conform to the environment2 in human evolution the environment is made to conform to the wants of the organism4 ,the one is unconscious and involuntary1 passive under the dominating laws of ,nature2 the other is conscious1 voluntary progress toward an ideal1 by the use1 among other means1 of the laws of ,nature4 ,the one is by change of external form--i4 e41 change of species--the other by change of brain-structure4 ,now1 does not the commencing of the cycle of this new evolution imply the closing of that of the old8 ,the two may overlap somewhat now1 but it is evident that1 when the cycle of human evolution culminates1 when highly civilized man shall have taken possession of the whole earth1 the whole organic kingdom must be readjusted to his wants4 ,all organic forms must be either domesticated or destroyed4 ,organic forms will no longer be modified by natural but wholly by artificial selection4 99 99 99 99 99 ,there are many other supposed objections which have been urged1 but these are mostly not objections to evolution1 but only to some special theory of evolution--,darwinian1 ,spencerian1 ,lamarckian1 or other4 ,origin of ,beauty4--,for example1 it has been urged that natural selection can only account for useful structures2 but beauty is as universal and as conspicuous in nature as use4 ,in many cases ,darwin has shown that beauty is useful1 and in such cases it is1 of course1 seized upon by selection and intensified4 ,thus1 the gorgeous coloring of birds and insects is largely due to sexual selection4 ,beauty is attractive1 and therefore the most beautiful prevail in securing reproductive opportunities4 ,this character is1 therefore1 perpetuated in the offspring1 and intensified from generation to generation4 ,but1 of course1 this can apply only to higher animals1 in which the sexes are separate and sexual union voluntary4 ,it can not apply to self-fertilizing hermaphrodites2 and yet in these1 also1 we often find the most gorgeous coloring4 ,again1 ,darwin has very ingeniously and successfully explained the case of the beauty and fragrance of flowers of hermaphroditic plants by another principle1 viz41 that of insect-selection4 ,insects are attracted by the most showy and fragrant flowers1 and thus become the means of carrying pollen from flower to flower1 insuring fertilization1 and especially cross-fertilization4 ,the most beautiful and fragrant flowers are most certain to be fertilized1 and thus beauty and fragrance become useful to the plant1 and therefore are selected and intensified4 ,these and many other cases of beauty may doubtless be explained by showing that it is useful2 but beauty which is without any use can not be explained by natural selection4 ,now1 as already said1 the most gorgeous beauty is lavishly distributed even among the lowest animals1 such as marine shells and polyps1 where no such explanation is possible4 ,the process by which such beauty is originated and intensified is wholly unknown to us4 ,incipient ,organs4--,again1 ,mivart has drawn attention to another difficulty in the way of natural selection as an explanation even of useful organs4 ,darwin does not1 of course1 attempt to account for the origin of varieties4 ,as we have already seen1 he assumes divergent variation of offspring as the necessary material on which natural selection operates4 ,he who shall explain the origin of varieties will have made another great step in completing the theory of evolution4 ,but not only does not natural selection explain the origin of varieties1 but neither can it explain the first steps of advance toward usefulness4 ,an organ must be already useful before natural selection can take hold of it to improve it4 ,it can not make it useful1 but only more useful4 ,for example1 if fins commenced as buds from the trunk1 it is difficult to see how they could be of any use1 and therefore how they could be improved by natural selection until they were of considerable size1 and especially until muscles were developed to move them4 ,until that time they would seem to be a hindrance to be removed by natural selection1 instead of a use to be preserved and improved4 ,it would seem that many organs must have passed through this incipient stage1 in which their use was prospective4 ,much that is very interesting might be said on these and similar points of difficulty1 but all this lies entirely aside from the scope of this work4 ,as already said1 these are not objections to evolution or derivation1 but only to ,darwinism1 or any other special theory1 as a sufficient explanation of the process of evolution4 ,they only show that we do not yet fully understand this process2 that there are still other and perhaps greater factors of evolution than is yet dreamed of in our philosophy4 ,in the foregoing chapters on special evidences1 and especially in the last two1 the reader will observe many points of doubt1 discussion1 and difference of opinion4 ,let it not be concluded on that account that the law of evolution is still in the region of uncertainty4 ,it can not be too strongly insisted on that the fact of evolution as a universal law must be kept distinct from the causes1 the factors1 the conditions1 the processes1 of evolution4 ,the former is certain1 the latter are still imperfectly understood4 ,,part ,,iii4 ,,the ,,relation ,,of ,,evolution ,,to ,,religious ,,thought4 ,,chapter ,i4 ,,introductory4 ,from what has preceded1 the reader will perceive that we regard the law of evolution as thoroughly established4 ,in its most general sense1 i4 e41 as a law of continuity1 it is a necessary condition of rational thought4 ,in this sense it is naught else than the universal law of necessary causation applied to forms instead of phenomena4 ,it is not only as certain as--it is far more certain than--the law of gravitation1 for it is not a contingent1 but a necessary truth like the axioms of geometry4 ,it is only necessary to conceive it clearly1 to accept it unhesitatingly4 ,the consensus of scientific and philosophical opinion is already well-nigh1 if not wholly1 complete4 ,if there are still lingering cases of dissent among thinking men1 it is only because such do not yet conceive it clearly--they confound it with some special form of explanation of evolution which they1 perhaps justly1 think not yet fully established4 ,we have sometimes in the preceding pages used the words evolutionist or derivationist2 they ought not to be used any longer4 ,the day is past when evolution might be regarded as a school of thought4 ,we might as well talk of gravitationist as of evolutionist4 ,if1 then1 evolution as a law be certain1 if1 moreover1 it is a law affecting not only one part of ,nature--the organic kingdom--and one department of science--biology--but the whole realm of ,nature and every department of science1 yea1 every department of thought1 changing our whole view of ,nature and modifying our whole philosophy1 the question presses upon us1 8,what will be its effect on religious belief1 and therefore on moral conduct80 ,this is a question of gravest import4 ,to answer it1 however imperfectly1 is the chief object of this work4 ,except for this1 it would probably never have been undertaken4 ,all that goes before is subsidiary to this4 ,but ,i will doubtless be met at the very threshold by an objection from the scientific side4 ,some will say--because it is the fashion now to say--that as simple1 honest truth-seekers1 we have nothing to do with its effect on religion and on life4 ,they say we must follow ,truth wherever she leads1 utterly regardless of what may seem to us moral consequences4 ,this ,i believe is a grave mistake1 the result of a reaction1 and on the whole a wholesome and noble reaction1 against the far more common mistake of sacrificing truth to a supposed good4 ,but the reaction1 as in most other cases1 has gone much too far4 ,there is a true philosophic ground of justification for the reluctance with which even honest truth-seekers accept a doctrine which seems harmful to society4 ,effect on life is1 and ought to be1 an important element in our estimate of the truth of any doctrine4 ,it is necessary for me to show this1 in order to justify this part of my work4 ,relation of the ,true and the ,good4--,there is a necessary and indissoluble connection between truth and usefulness4 ,we all at once admit this connection in one direction4 ,we all admit that a truth must eventually have its useful application4 ,it may not be now1 nor in ten years1 nor in a century1 nor even in a millennium1 but some time in the future it will vindicate its usefulness4 ,no truth is trivial or useless in its relation to human life1 for man is a part of ,nature1 and his life must be in accordance with the laws of ,nature4 ,every one admits this1 but not every one admits the converse proposition1 viz41 that whatever doctrine or belief1 in the long run and throughout the history of human advancement1 has tended to the betterment of our race1 must have in it an element of truth by virtue of which it has been useful2 for man's good can not be in conflict with the laws of ,nature4 ,also1 whatever in the long run and in the final outcome tends to the bad in human conduct1 ought to be received1 even by the honest truth-seeker1 with distrust as containing essential error4 ,the reason of this will now be further explained4 ,relation of ,philosophy to ,life4--,there are three primary divisions of our psychical nature1 viz41 sensuous1 intellectual1 and volitional or moral4 ,there are three corresponding primary processes necessary to make a complete rational and satisfactory philosophy3 7#a7 ,there is first the instreaming of the external world through the senses1 as impressions4 ,these we call facts or phenomena4 7#b7 ,the elaboration of these facts within1 by the intellect1 into a compact1 consistent structure4 ,this we call knowledge4 7#c7 ,the outgoing of this knowledge by the will into the world as right or wise conduct4 ,now these three are all equally necessary4 ,all these three portions of our complex nature are equally urgent to be satisfied4#ci ,but1 unfortunately1 scientific workers are too apt to think only #a and #b necessary--that true facts elaborated into consistent theory are all we need care for4 ,theologians and metaphysicians1 on the other hand1 seem to think only #b and #c necessary4 ,they elaborate a theory consistent in all its parts1 exquisitely woven in beautiful and delicate pattern1 and apparently satisfactory in its application to the right conduct of life1 but are less careful to inquire whether it is in harmony with facts derived from the senses4 ,but1 we repeat1 all three are equally necessary4 ,the first gathers the materials1 the second constructs the edifice1 the third1 by use1 by practical application1 tests whether it be a fit building to live in1 whether it is constructed on sound architectural principles4 ,the tendency of the olden time was to neglect the first1 the tendency of the present time is to neglect the third4 ,but we repeat with stronger emphasis that this third element is equally necessary4 ,all admit that successful application in art is the surest test of the truth of science4 ,now1 social conduct is the art corresponding to our philosophy of life1 and therefore is the sure test of its truth4 ,it follows1 therefore1 that unless all these three primary divisions of our nature are satisfied by any doctrine1 there must result an ineradicable confusion and discord in our psychical nature1 and cordial acceptance is not only impossible but irrational4 ,we insist upon this the more because it has become the fashion in these latter days of dominance of science1 to say that to inquire into effects on society is inconsistent with the scientific spirit1 and unworthy of the honest truth-seeker4 ,but1 observe1 ,i am speaking of effects on society only as a test of truth4 ,i would not swerve a hair's breadth from absolute devotion to truth4 ,it is necessary1 indeed1 to inquire into effects on society1 but we must inquire only in the patient spirit characteristic of the truth-seeker4 ,whatever is really true will surely vindicate itself by its beneficence1 if we will only wait patiently for final results4 ,evolution is no exception to this universal truth4 ,it will surely vindicate its beneficence1 but we must wait yet a little while--not very long4 ,so much it was necessary to say in justification of the inquiry which constitutes this third part of our work4 ,but1 after this justification1 the question returns with additional emphasis1 8,what will be the effect of the universal acceptance of the law of evolution on religious thought1 and through this on the right conduct of life80 ,there can be no doubt that evolution1 as a law affecting all science and every department of ,nature1 must fundamentally affect the whole realm of thought1 and profoundly modify our traditional views of ,nature1 of ,god1 and of man4 ,there can be no doubt that we are now on the eve of a great revolution4 ,but1 as in all great revolutions1 so in this1 the first fears as to its effects are greatly exaggerated4 ,to many1 both friends and foes of ,christianity1 evolution seems to sweep away the whole foundation1 not only of ,christianity1 but of all religion and morals1 by demonstrating a universal materialism4 ,many are ready to cry out in anguish1 8,ye have taken away our gods1 what have we more8 ,ye have destroyed our dearest hopes and noblest aspirations1 what more is left worth living for80 ,but ,i think all who are at all familiar with the history of the so-called conflict between religion and science will admit this is not the first time this cry has been raised against science4 ,they have heard this danger-cry so often that they begin to regard it as little more than a wolf-cry--scientific wolf in the religious fold4 ,it may not be amiss1 then1 to stop a moment to trace rapidly the main points of this conflict--to discuss the various forms of this scientific wolf4 ,first1 then1 it came in the form of the heliocentric theory of the planetary system4 ,we once thought the earth the center of the universe1 and so firm that it can not be moved4 ,but science shows that it moves about the sun1 and spins unceasingly on its axis4 ,every one has heard of the terror of the sheep produced by this discovery1 and the nearly tragic results to the bold scientist4 ,but now we look back with wonder that there should have been any trouble at all4 ,would any ,christian now consent to give up the grand conceptions of ,nature and of ,god thus opened to the human mind--the idea of infinite space full of worlds1 of which our earth is one1 moving in silent harmony as in a mystic dance8 ,verily1 this wolf has proved itself a harmless1 nay1 a very noble beast1 and lies down in peace with the lambs4 ,next1 it came in the shape of the law of gravitation1 as sustentation of the cosmos by law and resident forces4 ,the effect of this on religious thought was even more profound1 though less visible on the surface1 because only perceived by the most intelligent4 ,it seemed at that time to remove ,god from the course of ,nature4 ,this was the real ground of the skepticism of the last century1 and also the real motive of ,voltaire's ardent advocacy of ,newton's views before these were generally accepted in ,france4 ,but now1 who would give up this grand idea--this conception of law pervading infinite space--the same law which controls the falling of a stone guiding also the planetary orbs in their fiery courses8 ,this is indeed the divine spheral music1 inaudible but to the ear of science1 accompanying the celestial dance4 ,next1 it came in the form of the antiquity of the earth and of the cosmos4 ,the earth which we had fondly thought made specially for us about six thousand years ago2 sun1 moon1 and stars1 which we had vainly imagined shone only for our behoof--these1 science tells us1 existed and each performed its due course inconceivable ages before there was a man to till the ground or contemplate the heavens4 ,some of my readers may still remember the horror1 the angry dispute which followed the promulgation of these facts4 ,but now1 who would consent to give up the noble conception of infinite time thus opened to the human mind and become forever the heritage of man8 ,next1 it came in the form of the antiquity of man4 ,it is probable1 nay1 certain1 that man has inhabited the earth far longer than we had previously supposed we had warrant for believing4 ,the controversy on this question and the dread of its result has indeed not yet entirely subsided4 ,some timid people still look askance at this wolf1 but ,i think all intelligent people accept it and find it harmless4 ,next1 and last1 it comes now in the form of evolution--of the origin of all things1 even of organic forms1 by derivation--of creation by law4 ,we are even now in the midst of the terror created by this doctrine4 ,but what is evolution but law throughout infinite time8 ,the same law which now controls the development of an egg has presided over the creation of worlds4 ,infinite space and the universal law of gravitation2 infinite time and the universal law of evolution4 ,these two are the grandest ideas in the realm of thought4 ,the one is universal sustentation1 the other universal creation1 by law4 ,there is one law and one energy pervading all space and stretching through all time4 ,our religious philosophy has long ago accepted the one1 but has not yet had time to readjust itself completely to the other4 ,a few more years1 and ,christians will not only accept1 but love and cherish this also for the noble conceptions it gives of ,nature and of ,god4 ,but some will exclaim1 8,noble conceptions of ,god1 say you6 ,why1 it utterly obliterates the idea of ,god from the mind4 ,all other conflicts were for outworks--this strikes at the citadel4 ,all others required only readjustment of claims1 rectification of boundaries betwixt science and religion--this requires nothing less than unconditional surrender4 ,evolution is absolute materialism1 and materialism is incompatible with belief in ,god1 and therefore with religion of any kind whatsoever60 ,before proceeding any further1 it becomes necessary to remove this difficulty out of the way4 ,,chapter ,,ii4 ,,the ,,relation ,,of ,,evolution ,,to ,,materialism4 ,it is seen in the sketch given in the previous chapter that1 after every struggle between theology and science1 there has been a readjustment of some beliefs1 a giving up of some notions which really had nothing to do with religion in a proper sense1 but which had become so associated with religious belief as be to confounded with the latter--a giving up of some line of defense which ought never to have been held because not within the rightful domain of theology at all4 ,until the present the whole difficulty has been the result of misconception1 and ,christianity has emerged from every struggle only strengthened and purified1 by casting off an obstructing shell which hindered its growth4 ,but the present struggle seems to many an entirely different and far more serious matter4 ,to many it seems no longer a struggle of theology1 but of essential religion itself--a deadly life-and-death struggle between religion and materialism4 ,to many1 both skeptics and ,christians1 evolution seems to be synonymous with blank materialism1 and therefore cuts up by the roots every form of religion by denying the existence of ,god and the fact of immortality4 ,that the enemies of religion1 if there be any such1 should assume and insist on this identity1 and thus carry over the whole accumulated evidence of evolution as a demonstration of materialism1 although wholly unwarranted1 is not so surprising2 but what shall we say of the incredible folly of her friends in admitting the same identity6 ,a little reflection will explain this4 ,there can be no doubt that there is at present a strong and to many an overwhelming tendency toward materialism4 ,the amazing achievements of modern science2 the absorption of intellectual energy in the investigation of external nature and the laws of matter have created a current in that direction so strong that of those who feel its influence--of those who do not stay at home1 shut up in their creeds1 but walk abroad in the light of modern thought--it sweeps away and bears on its bosom all but the strongest and most reflective minds4 ,materialism has thus become a fashion of thought2 and1 like all fashions1 must be guarded against4 ,this tendency has been created and is now guided by science4 ,just at this time it is strongest in the department of biology1 and especially is evolution its stronghold4 ,this theory is supposed by many to be simply demonstrative of materialism4 ,once it was the theory of gravitation which seemed demonstrative of materialism4 ,the sustentation of the universe by law seemed to imply that ,nature operates itself and needs no ,god4 ,that time is passed4 ,now it is evolution and creation by law4 ,this will also pass4 ,the theory seems to many the most materialistic of all scientific doctrine only because it is the last which is claimed by materialism1 and the absurdity of the claim is not yet made clear to many4 ,the truth is1 there is no such necessary connection between evolution and materialism as is imagined by some4 ,there is no difference in this respect between evolution and any other law of ,nature4 ,in evolution1 it is true1 the last barrier is broken down1 and the whole domain of nature is now subject to law2 but it is only the last2 the march of science has been in the same direction all the time4 ,in a word1 evolution is not only not identical with materialism1 but1 to the deep thinker1 it has not added a feather's weight to its probability or reasonableness4 ,evolution is one thing and materialism quite another4 ,the one is an established law of nature1 the other an unwarranted and hasty inference from that law4 ,let no one imagine1 as he is conducted by the materialistic scientist in the paths of evolution from the inorganic to the organic1 from the organic to the animate1 from the animate to the rational and moral1 until he lands1 as it seems to him1 logically and inevitably1 in universal materialism--let no such one imagine that he has walked all the way in the domain of science4 ,he has stepped across the boundary into the domain of philosophy4 ,but1 on account of the strong tendency to materialism and the skillful guidance of his leaders1 there seems to be no such boundary2 he does not distinguish between the inductions of science and the inferences of a shallow philosophy2 the whole is accredited to science1 and the final conclusion seems to carry with it all the certainty which belongs to scientific results4 ,the fact that these materialistic conclusions are reached by some of the foremost scientists of the present day adds nothing to their probability4 ,in a question of science1 viz41 the law of evolution1 their authority is deservedly high1 but in a question of philosophy1 viz41 materialism1 it is far otherwise4 ,if the pure scientists smile when theological philosophers1 unacquainted with the methods of science1 undertake to dogmatize on the subject of evolution1 they must pardon the philosophers if they also smile when the pure scientists imagine that they can at once solve questions in philosophy which have agitated the human mind from the earliest times4 ,i am anxious to show the absurdity of this materialistic conclusion1 but ,i shall try to do so1 not by any labored argument1 but by a few simple illustrations4 #a4 ,it is curious to observe how1 when the question is concerning a work of ,nature1 we no sooner find out how a thing is made than we immediately exclaim3 8,it is not made at all1 it became so of itself60 ,so long as we knew not how worlds were made1 we of course concluded they must have been created1 but so soon as science showed how it was probably done1 immediately we say we were mistaken--they were not made at all4 ,so also1 so long as we could not imagine how new organic forms originated1 we were willing to believe they were created1 but1 so soon as we find that they originated by evolution1 many at once say1 8,we were mistaken2 no creator is necessary at all40 ,is this so when the question is concerning a work of man8 ,yes1 of one kind--viz41 the work of the magician4 ,here1 indeed1 we believe in him1 and are delighted with his work1 until we know how it is done1 and then all our faith and wonder cease4 ,but in any honest work it is not so2 but1 on the contrary1 when we understand how it is done1 stupid wonder is changed into intellectual delight4 ,does it not seem1 then1 that to most people ,god is a mere wonder-worker1 a chief magician4 ,but the mission of science is to show us how things are done4 ,is it any wonder1 then1 that to such persons science is constantly destroying their superstitious illusions8 ,but if ,god is an honest worker1 according to reason--i4 e41 according to law--ought not science rather to change gaping wonder into intelligent delight--superstition into rational worship8 #b4 ,again1 it is curious to observe how an old truth1 if it come only in a new form1 often strikes us as something unheard of1 and even as paradoxical and almost impossible4 ,a little over thirty years ago a little philosophical toy1 the gyroscope1 was introduced and became very common4 ,at first sight1 it seems to violate all mechanical laws1 and set at naught the law of gravitation itself4 ,a heavy-brass wheel1 four to five inches in diameter1 at the end of a horizontal axle1 six or eight inches long1 is set rotating rapidly1 and then the free end of the axis is supported by a string or otherwise4 ,the wheel remains suspended in the air while slowly gyrating4 ,what mysterious force sustains the wheel when its only point of support is at the end of the axle1 six or eight inches away8 ,scientific and popular literature were flooded with explanations of this seeming paradox4 ,and yet it was nothing new4 ,the boy's top1 that spins and leans and will not fall1 although solicited by gravity1 so long as it spins1 which we have seen all our lives without special wonder1 is precisely the same thing4 ,now1 evolution is no new thing1 but an old familiar truth2 but1 coming now in a new and questionable shape1 lo1 how it startles us out of our propriety6 ,origin of forms by evolution is going on everywhere about us1 both in the inorganic and the organic world4 ,in its more familiar forms1 it had never occurred to most of us that it was a scientific refutation of the existence of ,god1 that it was a demonstration of materialism4 ,but now it is pushed one step farther in the direction it has always been going--it is made to include also the origin of species--only a little change in its form1 and lo1 how we start6 ,to the deep thinker1 now and always1 there is and has been the alternative--materialism or theism4 ,god operates ,nature or ,nature operates itself2 but evolution puts no new phase on this old question4 ,for example1 the origin of the individual by evolution4 ,everybody knows that every one of us individually became what we now are by a slow process of evolution from a microscopic spherule of protoplasm1 and yet this did not interfere with the idea of ,god as our individual maker4 ,why1 then1 should the discovery that the species 7or first individuals of each kind7 originated by evolution destroy our belief in ,god as the creator of species8 #c4 ,it is curious and very interesting to observe the manner in which vexed questions are always finally settled1 if settled at all4 ,all vexed questions--i4 e41 questions which have tasked the powers of the greatest minds age after age--are such only because there is a real truth on both sides4 ,pure1 unmixed error does not live to plague us long4 ,error1 when it continues to live1 does so by virtue of a germ of truth contained4 ,great questions1 therefore1 continue to be argued pro and con from age to age1 because each side is in a sense--i4 e41 from its own point of view--true1 but wrong in excluding the other point of view2 and a true solution1 a true rational philosophy1 will always be found in a view which combines and reconciles the two partial1 mutually excluding views1 showing in what they are true and in what they are false--explaining their differences by transcending them4 ,this is so universal and far-reaching a principle that ,i am sure ,i will be pardoned for illustrating it in the homeliest and tritest fashion4 ,i will do so by means of the shield with the diverse sides1 giving the story and construing it1 however1 in my own way4 ,there is1 apparently1 no limit to the amount of rich marrow of truth that may be extracted from these dry bones of popular proverbs and fables by patient turning and gnawing4 ,we all remember1 then1 the famous dispute concerning the shield1 with its sides of different colors1 which we shall here call white and black4 ,we all remember how1 after vain attempts to discover the truth by dispute1 it was agreed to try the scientific method of investigation4 ,we all remember the surprising result4 ,both parties to the dispute were right and both were wrong4 ,each was right from his point of view1 but wrong in excluding the other point of view4 ,each was right in what he asserted1 and each wrong in what he denied4 ,and the complete truth was the combination of the partial truths and the elimination of the partial errors4 ,but we must not make the mistake of supposing that truth consists in compromise4 ,there is an old adage that truth lies in the middle between antagonistic extremes4 ,but it seems to us that this is the place of safety1 not of truth4 ,this is the favorite adage1 therefore1 of the timid man1 the time-server1 the fence-man1 not the truth-seeker4 ,suppose there had been on the occasion mentioned above one of these fence-philosophers4 ,he would have said3 8,these disputants are equally intelligent and equally valiant4 ,one side says the shield is white1 the other that it is black1 now truth lies in the middle2 therefore1 ,i conclude the shield is gray or neutral tint1 or a sort of pepper-and-salt40 ,do we not see that he is the only man who has no truth in him8 ,no2 truth is no heterogeneous mixture of opposite extremes1 but a stereoscopic combination of two surface views into one solid reality4 ,now1 the same is true of all vexed questions1 and ,i have given this trite fable again only to apply it to the case in hand4 ,there are three possible views concerning the origin of organic forms whether individual or specific4 ,two of these are opposite and mutually excluding2 the third combining and reconciling4 ,for example1 take the individual4 ,there are three theories concerning the origin of the individual4 ,the first is that of the pious child who thinks that he was made very much as he himself makes his dirt-pies2 the second is that of the street-gamin1 or of ,topsy1 who says3 8,i was not made at all1 ,i growed02 the third is that of most intelligent ,christians--i4 e41 that we were made by a process of evolution4 ,observe that this latter combines and reconciles the other two1 and is thus the more rational and philosophical4 ,now1 there are also three exactly corresponding theories concerning the origin of species4 ,the first is that of many pious persons and many intelligent clergymen1 who say that species were made at once by the ,divine hand without natural process4 ,the second is that of the materialists1 who say that species were not made at all1 they were derived1 8they growed40 ,the third is that of the theistic evolutionists1 who think that they were created by a process of evolution--who believe that making is not inconsistent with growing4 ,the one asserts the divine agency1 but denies natural process2 the second asserts the natural process1 but denies divine agency2 the third asserts divine agency by natural process4 ,of the first two1 observe1 both are right and both wrong2 each view is right in what it asserts1 and wrong in what it denies--each is right from its own point of view1 but wrong in excluding the other point of view4 ,the third is the only true rational solution1 for it includes1 combines1 and reconciles the other two2 showing wherein each is right and wherein wrong4 ,it is the combination of the two partial truths1 and the elimination of the partial errors4 ,but let us not fail to do perfect justice4 ,the first two views of origin1 whether of the individual or of the species1 are indeed both partly wrong as well as partly right2 but the view of the pious child and of the ,christian contains by far the more essential truth4 ,of the two sides of the shield1 theirs is at least the whiter and more beautiful4 ,but1 alas6 the great bar to a speedy settlement of this question and the adoption of a rational philosophy is not in the head but in the heart--is not in the reason but in pride of opinion1 self-conceit1 dogmatism4 ,the rarest of all gifts is a truly tolerant1 rational spirit4 ,in all our gettings let us strive to get this1 for it alone is true wisdom4 ,but we must not imagine that all the dogmatism is on one side1 and that the theological4 ,many seem to think that theology has a 8pre-emptive right0 to dogmatism4 ,if so1 then modern materialistic science has 8jumped the claim40 ,dogmatism has its roots deep-bedded in the human heart4 ,it showed itself first in the domain of theology1 because there was the seat of power4 ,in modern times it has gone over to the side of science1 because here now is the place of power and fashion4 ,there are two dogmatisms1 both equally opposed to the true rational spirit1 viz41 the old theological and the new scientific4 ,the old clings fondly to old things1 only because they are old2 the new grasps eagerly after new things1 only because they are new4 ,true wisdom and true philosophy1 on the contrary1 tries all things both old and new1 and holds fast only to that which is good and true4 ,the new dogmatism taunts the old for credulity and superstition2 the old reproaches the new for levity and skepticism4 ,but true wisdom perceives that they are both equally credulous and equally skeptical4 ,the old is credulous of old ideas and skeptical of new2 the new is skeptical of old ideas and credulous of new4 ,both deserve the unsparing rebuke of all right-minded men4 ,the appropriate rebuke for the old dogmatism has been already put in the mouth of ,job in the form of a bitter sneer3 8,no doubt ye are the people1 and wisdom shall die with you40 ,the appropriate rebuke for the new dogmatism1 though not put into the mouth of any ancient prophet1 ought to be uttered--,i will undertake to utter it here4 ,i would say to these modern materialists1 8,no doubt ye are the men1 and wisdom and true philosophy were born with you40 ,let it be observed that we are not here touching the general question of the personal agency of ,god in operating ,nature4 ,this we shall take up hereafter4 ,all that we wish to insist on now is that the process and the law of evolution does not differ in its relation to materialism from all other processes and laws of ,nature4 ,if the sustentation of the universe by the law of gravitation does not disturb our belief in ,god as the sustainer of the universe1 there is no reason why the origin of the universe by the law of evolution should disturb our faith in ,god as the creator of the universe4 ,if the law of gravitation be regarded as the ,divine mode of sustentation1 there is no reason why we should not regard the law of evolution as the ,divine process of creation4 ,it is evident that if evolution be materialism1 then is gravitation also materialism2 then is every law of ,nature and all science materialism4 ,if there be any difference at all1 it consists only in this3 that1 as already said1 here is the last line of defense of the supporters of supernaturalism in the realm of ,nature4 ,but being the last line of defense--the last ditch--it is evident that a yielding here implies not a mere shifting of line1 but a change of base2 not a readjustment of details only1 but a reconstruction of ,christian theology4 ,this1 ,i believe1 is indeed necessary4 ,there can be little doubt in the mind of the thoughtful observer that we are even now on the eve of the greatest change in traditional views that has taken place since the birth of ,christianity4 ,but let no one be greatly disturbed thereby4 ,for as then1 so now1 change comes not to destroy but to fulfill all our dearest hopes and aspirations2 as then1 so now1 the germ of living truth has1 in the course of ages1 become so encrusted with meaningless traditions which stifle its growth1 that it is necessary to break the shell to set it free2 as then1 so now1 it has become necessary to purge religious belief of dross in the form of trivialities and superstitions4 ,this has ever been and ever will be the function of science4 ,the essentials of religious faith it does not1 it can not1 touch1 but it purifies and ennobles our conceptions of ,deity1 and thus elevates the whole plane of religious thought4 ,it will not1 of course1 be expected of me to give1 even in briefest outline1 a system of reconstructed ,christian thought4 ,such an attempt would be wholly unbecoming4 ,time1 very much time1 and the co-operation of many minds1 bringing contributions from many departments of thought1 is necessary for this4 ,in a word1 it can only itself come by a gradual process of evolution4 ,but from the point of view of science some very fundamental changes in traditional views are already plain4 ,of these the most fundamental and important are our ideas concerning ,god1 ,nature1 and man in their relations to one another4 ,these will form the subject of the next three chapters4 ,,chapter ,,iii4 ,,the ,,relation ,,of ,,god ,,to ,,nature4 ,we have already said that evolution does not differ essentially from other laws of ,nature in its bearing on religious belief4 ,it only reiterates and enforces with additional emphasis what ,science1 in all its departments1 has been saying all along4 ,the difficulties in the way of certain traditional views have pressed with ever increasing force upon the thoughtful mind ever since the birth of modern science4 ,all along1 an issue has been gathering1 but put off from time to time by compromise1 until now1 at last1 the issue is forced upon us and compromise is exhausted4 ,the issue 7let us look it squarely in the face7 is3 ,either ,god is far more closely related with ,nature1 and operates it in a more direct way than we have recently been accustomed to think1 or else 7mark the alternative7 ,nature operates itself and needs no ,god at all4 ,there is no middle ground tenable4 ,let us trace rapidly the growth of this issue4 ,the old idea and the most natural to the religious mind was the direct agency of ,god in every event and phenomenon of ,nature4 ,this view is nobly expressed in the noblest literature in the world--in the ,hebrew and ,christian ,scriptures3 8,he looketh on the earth and it trembleth4 ,he toucheth the hills and they smoke40 8,he maketh his sun to rise on the evil and on the good1 and sendeth his rain on the just and on the unjust40 ,but now comes ,science and explains all these phenomena by natural laws and resident forces1 and we all accept her explanation4 ,thus1 one by one the phenomena of ,nature are explained by the operation of resident forces according to natural laws1 until the whole course of ,nature1 as we now know it1 has been1 or will be1 or conceivably may be1 thus explained4 ,thus has gradually grown up1 without our confessing it1 a kind of scientific polytheism--one great ,jehovah1 perhaps1 but with many agents or sub-gods1 each independent1 efficient1 and doing all the real work in his own domain4 ,the names of these1 our gods1 are gravity1 light1 heat1 electricity1 magnetism1 chemical affinity1 etc41 and we are practically saying3 8,these be your gods1 ,o ,israel1 which brought you out of the land of ,egyptian darkness and ignorance4 ,these be the only gods ye need fear1 and serve1 and study the ways of40 ,what1 then1 is practically the notion which most people seem to have of the relation of ,deity to ,nature8 ,it is that of a great master-mechanic far away above us and beyond our reach1 who once upon a time1 long ago1 and once for all1 worked1 created matter1 endowed it with necessary properties and powers1 constructed at once out of hand this wonderful cosmos with its numberless wheels within wheels1 endowed it with forces1 put springs in it1 wound it up1 set it a-going1 and then--rested4 ,the thing has continued to go of itself ever since4 ,he might have not only rested but slept1 and the thing would have gone of itself4 ,he might not only have slept but died1 and still the thing would have continued to go of itself4 ,but1 no1 ,i forget4 ,he must not sleep or die1 for the work is not absolutely perfect4 ,there are some things too hard even for ,him to do in this masterful1 god-like way4 ,there are some things which even ,he can not do except in a 'prentice-like1 man-like way4 ,the hand must be introduced from time to time to repair1 to rectify1 to improve1 especially to introduce new parts1 such as new organic forms4 ,such was the state of the compromise until twenty-five years ago4 ,nature is sufficient of itself for its course and continuance1 but not for origins of at least some new parts4 ,such was the state of the compromise until ,darwin and the theory of evolution4 ,but1 now1 even this poor privilege of occasional interference is taken away4 ,now1 origins1 as well as courses1 are reduced to resident forces and natural law4 ,now1 ,nature is sufficient of itself1 not only for sustentation1 but also for creation4 ,thus1 ,science has seemed to push ,him farther and farther away from us1 until now1 at last1 if this view be true1 evolution finishes the matter by pushing ,him entirely out of the universe and dispensing with ,him altogether4 ,this1 of course1 is materialism4 ,but this is no new view now brought forward for the first time by evolution4 ,on the contrary1 evolution only finishes what science has been doing all along4 ,see1 then1 how the issue is forced4 ,either ,nature is sufficient of itself and wants no ,god at all1 or else this whole idea1 the history of which we have been tracing1 is radically false4 ,we have here given by science either a demonstration of materialism or else a reductio ad absurdum4 ,which is it8 ,i do not hesitate a moment to say it is a reductio ad absurdum4 ,and ,i believe that evolution has conferred an inestimable benefit on philosophy and on religion by forcing this issue and compelling us to take a more rational view4 ,what1 then1 is the alternative view8 ,it is the utter rejection with ,berkeley and with ,swedenborg of the independent existence of matter and the real efficient agency of natural forces4 ,it is the frank return to the old idea of direct divine agency1 but in a new1 more rational1 less anthropomorphic form4 ,it is the bringing together and complete reconciliation of the two apparently antagonistic and mutually excluding views of direct agency and natural law4 ,such reconciliation we have already seen is the true test of a rational philosophy4 ,it is the belief in a ,god not far away beyond our reach1 who once long ago enacted laws and created forces which continue of themselves to run the machine we call ,nature1 but a ,god immanent1 a ,god resident in ,nature1 at all times and in all places directing every event and determining every phenomena--a ,god in whom in the most literal sense not only we but all things have their being1 in whom all things consist1 through whom all things exist1 and without whom there would be and could be nothing4 ,according to this view the phenomena of ,nature are naught else than objectified modes of divine thought1 the forces of ,nature naught else than different forms of one omnipresent divine energy or will1 the laws of ,nature naught else than the regular modes of operation of that divine will1 invariable because ,he is unchangeable4 ,according to this view the law of gravitation is naught else than the mode of operation of the divine energy in sustaining the cosmos--the divine method of sustentation2 the law of evolution naught else than the mode of operation of the same divine energy in originating and developing the cosmos--the divine method of creation2 and ,science is the systematic knowledge of these divine thoughts and ways--a rational system of natural theology4 ,in a word1 according to this view1 there is no real efficient force but spirit1 and no real independent existence but ,god4 ,but some will object that this is pure ,idealism4 ,yes1 but far different from what usually goes under that name4 ,the ideal philosophy as usually understood regards the external world as having no real objective existence outside of ourselves--as objectified mental states of the observer--as literally such stuff as dreams are made of--as a mere phantasmagoria of trooping shadows having no real existence but in the mind of the dreamer1 and each dreamer makes his own world4 ,not so in the idealism above presented4 ,according to this the external world is the objectified modes1 not of the mind of the observer1 but of the mind of ,god4 ,according to this1 the external world is not a mere unsubstantial figment or dream1 but for us a very substantial objective reality surrounding us and conditioning us on every side4 ,again1 it will be objected that this is pure ,pantheism4 ,again1 we answer 8yes40 ,call it so if you like1 but far different from what goes under that name1 far different from the pantheism which sublimates the personality of the ,deity into all-pervading unconscious force1 and thereby dissipates all our hopes of personal relation with him4 ,properly understood1 we believe this view completely reconciles the two antagonistic and mutually excluding views of impersonal pantheism and anthropomorphic personalism1 and is therefore more rational than either4 ,the discussion of this most important point can only come up after the next chapter1 because the argument for the personality of ,deity is derived1 not from without by the study of ,nature1 but from within in our own consciousness4 ,we therefore put off its discussion for the present4 ,but1 finally1 some will object1 8,we can not live and work effectively under such a theory unless1 indeed1 we escape through pantheism40 ,it may1 alas6 be true that this view brings us too near ,him in our sense of spiritual nakedness and shortcoming4 ,it may1 indeed1 be that we can not live and work in the continual realized presence of the ,infinite4 ,it may1 indeed1 be that we must still wear the veil of a practical materialism on our hearts and minds4 ,it may1 indeed1 be that in our practical life and scientific work we must still continue to think of natural forces as efficient agents4 ,but1 if so1 let us at least remember that this attitude of mind must be regarded only as our ordinary work-clothes--necessary work-clothes it may be of our outer lower life--to be put aside when we return home to our inner higher life1 religious and philosophical4 ,,chapter ,,iv4 ,,the ,,relation ,,of ,,man ,,to ,,nature4 ,there are two widely distinct views concerning the relation of man to ,nature2 the one as old as the history of human thought1 the other only now urged upon us by modern science4 ,according to the one1 man is the counterpart and equivalent of ,nature4 ,he alone has--in fact is--an immortal spirit1 and therefore he belongs to a world of his own4 ,according to the other1 man is but a part1 a very insignificant part of ,nature1 and connected in the closest way with all other parts1 especially with the animal kingdom4 ,he has no world of his own1 nor even kingdom of his own3 he belongs to the animal kingdom4 ,in that kingdom he has no department of his own3 he is a vertebrate4 ,in the department of vertebrates he has no privileged class of his own3 he is a mammal4 ,in the class of mammals he has no titled order of his own3 he is a primate1 and shares his primacy with apes4 ,it is doubtful if he may enjoy the privacy of a family of his own--the ,hominid--for the structural differences between man and the anthropoid apes are probably not so great as between the sheep family and the deer family4 ,now it is evident that these two are only views from different points1 psychical and structural4 ,from the psychical point of view it is simply impossible to exaggerate the wideness of the gap that separates man from even the highest animals4 ,from this point of view man must be set over as an equivalent1 not only to the whole animal kingdom1 but to the whole of ,nature besides4 ,from the structural point of view1 on the contrary1 it is impossible to exaggerate the closeness of the connection4 ,man's body is identified with all ,nature in its chemical constituents1 with the body of all animals in its functions1 with all vertebrates1 especially mammals1 in its structure4 ,bone for bone1 muscle for muscle1 ganglion for ganglion1 almost nerve-fiber for nerve-fiber1 his body corresponds with that of the higher animals4 ,whether he was derived from lower animals or not1 certain it is that his structure even in the minutest details is precisely such as it would be if he were thus derived by successive slight modifications4 ,now1 of these two views1 the latter has been in recent times enormously productive in increasing our knowledge4 ,anatomy has become truly scientific only through comparative anatomy2 physiology through comparative physiology2 embryology through comparative embryology4 ,sociology is fast following in the same line1 and becoming scientific through comparative sociology4 ,is not the same true also of psychology8 ,will not psychology become truly scientific only through comparative psychology1 i4 e41 by the study of the spirit of man in relation to what corresponds to it in lower animals8 ,but this view and this method1 when pushed to what seems to many their logical conclusion1 end in identification of man with mere animals1 of spirit with mere physical and chemical forces1 immortality with mere conservation of energy1 and thus leads to blank and universal materialism4 ,thus1 while it increases our knowledge1 it destroys our hopes4 ,is there any escape8 ,there is4 ,the two extreme views given above are not irreconcilable4 ,as already said1 they are only views from different points1 and therefore1 although both true1 are equally one-sided and partial1 and a true and rational philosophy1 in this as in all other cases of vexed questions1 is found only in a higher view1 which combines and reconciles these mutually excluding extremes4 ,can we find such a view8 ,i think we can4 ,let us first1 however1 trace some of the stages of this scientific materialism4 ,there are two main branches of the argument for materialism3 one derived from brain-physiology1 the other from evolution4 ,as we wish to be perfectly fair1 we will present and even press the argument in both these directions1 although the latter alone bears directly on the subject in hand4 ,in recent times1 physiology has made great and1 to many1 startling advances in the direction of connecting mental phenomena with brain-changes4 ,physiologists have established the correlation of vital with chemical and physical forces1#dj and probably in some sense1 at least1 of mental with vital forces4 ,they have proved1 in every act of perception1 first a physical change in a nerve-terminal1 then a propagated thrill along a nerve-fiber1 and then a resulting change1 physical or chemical1 in the brain2 and in every act of volition1 a change first in a brain-cell1 then1 a return thrill along a nerve-fiber1 and a resulting contraction of a muscle4 ,even the velocity of the transmission to and fro has been measured1 and the time necessary to produce brain-changes estimated4 ,they have also established the existence of physical and chemical changes in the brain corresponding to every change of mental state1 and with great probability an exact quantitative relation between these changes of brain and the corresponding changes of mind4 ,in the near future they may do more3 they may localize all the different faculties and powers of the mind1 each in its several place in the brain1 and thus lay the foundations of a truly scientific phrenology4 ,in the far-distant future we may possibly do much more4 ,we may connect each kind of mental state with a different and distinctive kind of brain-change4 ,we may find1 for example1 a right-handed rotation of atoms associated with love1 and a left-handed rotation associated with hate1 or a gentle sideways oscillation associated with consciousness1 and a vertical pounding associated with will4 ,now1 suppose all this1 and even much more1 be done in the way of associating1 both in degree and in kind1 mental changes with brain-changes4 ,what then8 8,why10 say the materialists1 8we thereby identify mind with matter1 mental forces with material forces4 ,thought1 emotion1 consciousness and will become products of the brain1 in the same sense as bile is a product of the liver1 or urea a product of the kidneys40 ,such is1 in brief1 the argument4 ,now1 the answer3 ,we may do all we have supposed and much more4 ,we may push our knowledge in this direction as far as the boldest imagination can reach1 and even then we are no nearer the solution of this mystery of the relation of brain-changes and mental changes than we are now4 ,even then it would be impossible for us to conceive how brain-changes produce mental changes or vice versa4 ,physical changes in sense-organs1 transmitted along nerve-fibers1 determine changes in brain-substance4 ,so much is intelligible4 ,but now there appear--how it is impossible to imagine--consciousness1 thought1 emotion1 etc4--phenomena of an entirely different order1 belonging to an entirely different world4 ,so different1 that it is impossible to imagine the nature of the nexus between1 or to construe the one in terms of the other4 ,brain-cells are agitated and thought appears3 ,aladdin's lamp is rubbed1 and the genie appears4 ,there is just as much intelligible causal relation between the two sets of phenomena in the one case as in the other4 ,now1 this mystery is not of the nature of those which disappear under the light of knowledge4 ,on the contrary1 science only brings it out in sharper relief1 and emphasizes its absolute unsolvableness4 ,suppose an absolutely perfect knowledge1 perfect in degree1 but human in kind4 ,suppose an ideally perfect science--a science which has so completely subdued its domain1 and reduced it to such perfect simplicity1 that the whole cosmos may be expressed in a single mathematical formula--a formula which1 worked out with plus signs1 would give every phenomenon and event which shall ever occur in the future1 and with minus signs every phenomenon and event which has ever occurred in the past4 ,surely1 this is an ideally perfect science4 ,yet1 even to such a science1 the relation of brain-changes to mental states would be as great a mystery as now4 ,it would even come out in stronger relief1 because so many other apparent mysteries would disappear4 ,like the essential nature of matter or the ultimate cause of force1 this relation lies evidently beyond the domain of science4 ,it requires some other kind of knowledge than human to understand it4 ,but materialists insist so much on the identity of brain-physiology with psychology1 that even at the risk of tediousness we will multiply illustrations in order1 if possible1 to make this point still clearer4 ,suppose1 then1 we exposed the brain of a living man in a state of intense activity4 ,suppose1 further1 that our senses were absolutely perfect1 so that we could see every change1 of whatever sort1 taking place in the brain-substance4 ,what would we see8 ,obviously nothing but molecular changes1 physical and chemical2 for to the outside observer there is absolutely nothing else there to see4 ,but the subject of this experiment sees nothing of all this4 ,his experiences are of a different order1 viz41 consciousness1 thought1 emotions1 etc4 ,viewed from the outside1 there is--there can be--nothing but motions2 viewed from the inside1 nothing but thought1 etc4--from the one side1 only physical phenomena2 from the other side1 only psychical phenomena4 ,is it not plain that1 from the very nature of the case1 it must ever be so8 ,certain vibrations of brain molecules1 certain oxidations with the formation of carbonic acid1 water1 and urea on the one side1 and there appear on the other sensations1 consciousness1 thoughts1 desires1 volitions4 ,there are1 as it were1 two sheets of blotting-paper pasted together4 ,the one is the brain1 the other the mind4 ,certain ink-scratches or blotches1 utterly meaningless on the one1 soak through and appear on the other as intelligible writing1 but how we know not1 and can never hope to guess4 ,but when the paste dissolves1 shall the writing remain8 ,we shall see4 ,but some will object4 ,there is nothing specially strange and unique in all this1 for the same mystery underlies the essential nature of all kinds of force and matter1 and therefore all phenomena4 ,true enough1 but with this difference4 ,physical and chemical forces and phenomena are indeed incomprehensible in their essential nature2 but once accept their existence1 and all their different forms are mutually convertible1 construable in terms of each other and all in terms of motion4 ,but it is impossible by any stretch of the imagination to thus construe mental forces and mental phenomena4 ,it may1 indeed1 be impossible to conceive how came the plane of material existence1 but1 standing on that plane1 all phenomena fall into intelligible order4 ,but there is another plane above this one1 having no intelligible relation with it4 ,we must climb up and stand on this before its phenomena fall into intelligible order4 ,in a word1 material forces and phenomena are1 indeed1 a mystery1 but only of the first order4 ,but mental and moral forces and phenomena are a mystery even from the standpoint of the other1 and are therefore a mystery of the second order--a mystery within a mystery4 ,we repeat1 then1 with additional emphasis after this examination1 that we can not imagine between physical and psychical phenomena a relation of cause and effect in the same sense in which we use these terms in physical science1 although in some sense there is doubtless such a relation4 ,if man were the only animal we had to deal with1 there would be no standing ground left for materialism4 ,but there is still another difficulty which sticks deeper4 ,it is that suggested by the law of evolution and enforced by the comparative method4 ,relation of ,man to ,animals4--,man1 we say1 is endowed with1 is1 in fact1 an immortal spirit4 ,what is spirit8 ,we know things only by their phenomena2 what are the phenomena of spirit8 ,consciousness1 will1 intelligence1 memory1 love1 hate1 fear1 desire--surely these are some of them4 ,but has not a dog or a monkey all these8 ,pressed with this difficulty1 some have indeed felt compelled to accord immortal spirit to higher animals4 ,but we can not stop here4 ,if to these1 then also to all animals2 for we have here only a sliding scale without break4 ,can we stop now and make it coextensive with sentiency8 ,no2 for the lowest animals and lowest plants merge into each other so completely that no one can draw the line between them with certainty4 ,we must extend it to plants also4 ,shall we stop here and make immortal spirit coextensive with life8 ,we can not2 for life-force is certainly correlated with1 transmutable into1 and derivable from1 physical and chemical forces4 ,we must extend it into dead nature also4 ,therefore1 everything is immortal or none4 ,our boasted immortality by continued extension becomes thinner and thinner until it evaporates into thin air4 ,it becomes naught else than conservation of energy1 and not1 as we had hoped1 conservation of self-conscious personality4 ,this may be interesting as a scientific fact2 but of what value to us personally is a continued existence of our spiritual forces as heat1 light1 electricity1 or any other form of unconscious force8 ,thus1 then1 if once we pass the gap between man and the higher animals1 there is no possibility of a stopping-place anywhere4 ,such is the difficulty presented by comparison in the taxonomic series4 ,take now the embryonic series4 ,each one of us1 individually1 was formed gradually by a process of evolution1 from a microscopic spherule of protoplasm undistinguishable in structure from the lowest forms of protozoal life4 ,now1 in this gradual process of evolution1 where did immortal spirit come in8 ,was it in the germ-cell8 ,then why deny it to the protozoan8 ,was it at the quickening1 or at the birth1 or at the moment of first self-consciousness1 or at some later period of capacity of abstract thought8 ,again1 when it did come in1 was it something superadded or did it grow out of something already existing in the embryo or the infant8 ,or take the evolution series from protozoan to man4 ,this we have already seen is similar in outline to the other two4 ,now1 in the gradual evolution of the animal kingdom throughout all geological time1 terminating in man1 when did immortal spirit come in8 ,did it enter with life1 or with sentient life1 or somewhere in the ascending scale of animals1 or with the advent of man8 ,if with man1 was it some new thing added at once out of hand1 or did it grow out of something already existing in animals8 ,this last1 we are persuaded1 is the only tenable view--the only view that can effect that reconciliation between the two extreme1 mutually excluding views now usually held1 which1 as already seen1 is the true test of a rational philosophy4 ,i believe that the spirit of man was developed out of the anima or conscious principle of animals1 and that this1 again1 was developed out of the lower forms of life-force1 and this in its turn out of the chemical and physical forces of ,nature2 and that at a certain stage in this gradual development1 viz41 with man1 it acquired the property of immortality precisely as it now1 in the individual history of each man at a certain stage1 acquires the capacity of abstract thought4 ,this is1 in brief1 the view which ,i wish to enforce4 ,the reader must understand1 however1 that this is my own view only1 a view for which ,i have earnestly contended for twenty years4 ,it appeals1 therefore1 not to authority1 but only to reason4 ,i wish now to present it as briefly as possible4 ,first1 then1 ,i would draw attention to the fact that there is nothing wholly exceptional in such transformation with the sudden appearance of new powers and properties2 but1 on the contrary1 it is in accordance with many analogies in the lower forces1 and therefore a priori not only credible but probable4 ,for example1 force and matter may be said to exist now on several distinct planes raised one above another4 ,there is a sort of taxonomic scale of force and matter4 ,these are1 #a1 the plane of elements2 #b1 the plane of chemical compounds2 #c1 the plane of vegetal life2 #d1 the plane of animal life2 and #e1 the plane of rational and1 as we hope1 immortal life4 ,each plane has its own appropriate force and distinctive phenomena4 ,on the first operates physical forces1 producing physical phenomena only--for the operation of chemical affinity immediately raises matter to the next plane4 ,on the second plane operates1 in addition to physical1 also chemical forces1 producing all those changes by action and reaction1 the study of which constitutes the science of chemistry4 ,on the third plane1 in addition to the two preceding forces1 with their characteristic phenomena1 operates also life-force1 producing the distinctive phenomena characteristic of living things4 ,on the fourth plane1 in addition to all lower forces and their phenomena1 operates also a higher form of life-force characteristic of animals1 producing the phenomena characteristic of sentient life1 such as sensation1 consciousness1 and will4 ,on the fifth plane1 in addition to all the preceding forces and phenomena1 we have also the forces and phenomena characteristic of rational and moral life4 ,now1 although there are doubtless great differences of level on each of these planes1 yet there is a very distinct break between each4 ,although there are various degrees of the force characteristic of each1 yet the difference between the characteristic forces is one of kind as well as of degree4 ,although energy by transmutation may take all these different forms1 and thus does now circulate up and down through all these planes1 yet the passage from one plane upward to another is not a gradual passage by sliding scale1 but at one bound4 ,when the necessary conditions are present1 a new and higher form of force at once appears1 like a birth into a higher sphere4 ,for example1 when hydrogen and oxygen are brought together under proper conditions1 water is born--a new thing with new and wholly unexpected properties and powers1 entirely different from those of its components4 ,when ,,co#b1 ,h#b,o1 and ,,nh#c are brought together under suitable conditions1 viz41 in the green leaves of plants1 in the presence of sunlight1 living protoplasm is then and there born1 a something having entirely new and unexpected powers and properties4 ,it is no gradual process but sudden1 like birth into a higher sphere4 ,now1 there is not the least doubt that the same is true of the order and manner of the first appearance of the natural forces in the phylogenic series4 ,in the history of the evolution of the cosmos1 the forces of ,nature have appeared successively and suddenly when conditions became favorable4 ,there was a time in the history of the earth when only physical forces existed1 chemical affinity being held in abeyance by the intensity of the heat4#da ,by gradual cooling1 chemical affinity at a certain stage came into being--was born1 a new form of force1 with new and peculiar phenomena1 though doubtless derived from the preceding4 ,ages upon ages passed away until the time was ripe and conditions were favorable1 and life appeared--a new and higher form of force1 producing a still more peculiar group of phenomena1 but still1 as ,i believe1 derived from the preceding4 ,ages upon ages again passed away1 during which this life-force took on higher and higher forms--in the highest foreshadowing and simulating reason itself--until finally1 when the time was fully ripe and conditions were exceptionally favorable1 spirit1 self-conscious1 self-determining1 rational1 and moral1 appeared--a new and still higher form of force1 but still1 as ,i am persuaded1 derived from the preceding4 ,now1 that these forces are really of derivative origin is proved by the fact that we see every step of this process taking place daily under our very eyes4 ,i pass over the conversion of physical into chemical force because this is admitted on all hands4 ,i begin1 therefore1 with vital force4 ,sunlight falling on green leaves disappears as light and reappears as life--is consumed in doing the work of decomposing ,,co#b1 ,h#b,o1 and ,,nh#c1 and the ,c1 ,h1 ,o1 and ,n thus set free from previous combination unite to form living protoplasm4#db ,again1 in the embryonic history of every animal we see the next change take place--i4 e41 the emergence of the psychic out of the vital4 ,in the germ-cell1 in the egg1 and even in the early stages of the embryo1 there is no distinctive animal life--i4 e41 no consciousness1 nor volition1 nor response of any kind to stimulus4 ,at a certain stage distinctive animal or psychic life appears4 ,we call it quickening4 ,materials for psychology are now present for the first time4 ,in man alone1 and that only some time after physical birth1 we see the last change4 ,the new-born child has animal life only4 ,the emergence of self-consciousness--a change so wonderful that it may well be called the birth of spirit--takes place only at the age of two to three years4 ,now for the first time we have phenomena distinctive of humanity4 ,but some will ask1 8,how is this consistent with immortality80 ,in answer1 let me again remind the reader that with every new form of force1 with every new birth of the universal energy into a higher plane1 there appear new1 unexpected1 and1 previous to experience1 wholly unimaginable properties and powers4 ,this last birth is of course no exception4 ,why may not immortality be one of these new properties8 ,but this point is so important that we must treat it more fully4 ,remember1 then1 the view of the relation of ,god to ,nature1 already explained4 ,remember that the forces of ,nature are naught else than different forms of the one omnipresent ,divine energy4 ,remember that1 as just shown1 this ,divine omnipresent energy has taken on successively higher and higher forms in the course of cosmic time4 ,now this upward movement has been wholly by increasing individuation1 not only of matter1 but also of force4 ,this universal ,divine energy1 in a generalized condition1 unindividuated1 diffused1 pervading all ,nature1 is what we call physical and chemical force4 ,the same energy in higher form1 individuating matter1 and itself individuated1 but only yet very imperfectly1 is what we call the life-force#dc of plants4 ,the same energy1 more fully individuating matter and itself more fully individuated1 but not completely1 we call the anima of animals4 ,this anima1 or animal soul1 as time went on1 was individuated more and more until it resembled and foreshadowed the spirit of man4 ,finally1 still the same energy1 completely individuated as a separate entity and therefore self-conscious1 capable of separate existence and therefore immortal1 we call the spirit of man4 ,according to this view1 the vital principle of plants and the anima of animals are but different stages of the development of spirit in the womb of ,nature3 in man at last it came to birth4 ,in plants and animals it was in deep embryo sleep--in the latter1 quickened1 indeed1 but not viable--still unconscious of self1 incapable of independent life1 with physical1 umbilical connection with ,nature2 but now at last in man1 separated from ,nature1 capable of independent life1 born into a new and higher plane of existence4 ,separated1 but not wholly3 ,nature is no longer gestative mother1 but still nursing mother of spirit4 ,as the organic embryo at birth reaches independent material or temporal life1 even so spirit embryo by birth attains independent spiritual or eternal life4 ,although birth is its truest correspondence and best illustration1 yet we may vary the illustration in many ways3 #a4 ,nature may be likened to a level water-surface4 ,this represents unindividuated physical and chemical force4 ,on this surface some individuating force pulls up a portion of the water into a commencing drop4 ,this represents the condition of spirit in plants4 ,or by greater force the surface may be lifted higher into a nipple-like eminence simulating a drop1 or even into an almost complete drop with only a neck-like connection with the general surface4 ,this represents the condition of spirits in the higher animals4 ,in all these cases1 even though the drop be nearly completed1 if we remove the individuating or lifting force1 the commencing drop is immediately drawn back by cohesion and refunded into the general watery surface4 ,but1 once complete the drop1 and there is no longer any tendency to revert1 even though the lifting force is removed4 ,this represents the condition of spirit in man4 #b4 ,or ,nature may1 again1 be likened to a water-surface beneath which the anima of animals is deeply and tranquilly submerged1 wholly unknowing of any higher1 freer world above4 ,in man spirit emerges above the surface into a higher world1 looks down on ,nature beneath him1 around on other emerged spirits about him1 and upward to the ,father of all spirits above him4 ,emerged1 but not wholly free--head above1 but not yet foot-loose4 #c4 ,or1 again3 ,as a planet must break away from physical1 cohesive connection with the central sun 7planet-birth7 in order to enter into higher gravitative relations1 which thenceforward determine all its movements in beautiful harmony2 as the embryo must break away from physical umbilical connection with the mother in order to enter into higher spiritual bonds of love1 which thenceforward determine all their mutual relations--even so spirit must break away from physical and material connection with the forces of ,nature1 which are but the omnipresent ,divine energy1 in order thereby to enter into higher relations of filial love to ,god and brotherly love to man4 #d4 ,as the new-born child differs little in grade of physical organization from the mature but unborn embryo1 but at the moment of birth there is a sudden and complete change1 not so much in the grade of organization but in the whole plane of existence--a change absolutely necessary for further advance1 for another cycle of life2 even so at the moment of the origin of man1 howsoever this may have been accomplished1 there may have been no great change in the grade of psychical structure1 but yet a complete change in the plane of psychical life--a change absolutely necessary for further advance1 for another cycle of evolution4 ,in both cases there is a sudden entrance into a new world1 the sudden appearance of a new creature with entirely different capacities--a passing out of an old world1 a waking up in a new and higher4 ,according to this view1 man alone is a child of ,god1 capable of separate spirit-life--separate but not yet wholly independent of ,nature4 ,as already said1 ,nature is no longer gestative mother1 but still nursing mother of spirit--we are weaned only by death4 #e4 ,or1 again3 ,as in passing up the organic scale1 we find all grades of completeness of organic individuality1 an increasing individuation of bodily form which completes itself as a perfect organic individual only in the higher animals1 so1 also1 in passing up the dynamic scale1 force or energy is individuated more and more until the process reaches completeness as a spirit-individual or dynamic individual--a person only in man4 ,organic individuality completes itself in animals4 ,psychic individuality only in man4 #f4 ,one more illustration and the last4 ,the animal body may be likened to an exquisitely adjusted instrument of communication between two worlds--the material world without and the spiritual world within4 ,the key-boards of this marvelous instrument are the nerve-terminals of the sense-organs in contact with the material world1 and the brain-cells in touch with the spirit-world4 ,external ,nature plays on the one by sensation and determines changes in spirit4 ,spirit plays on the other by will and muscular contraction1 and determines changes in external ,nature4 ,now1 in animals spirit is fast asleep or at most dreaming1 or even perhaps somnambulistic1 but at least unconscious of self1 and acts only by stimulus--only responds in some sense automatically as sleepers do4 ,in man spirit is wide awake and may respond automatically like animals1 or may choose not to respond at all4 ,moreover1 it acts freely in its own domain--the world of ideas--without external stimulus2 or of its own free-will may initiate changes in the external world4 ,with ,god all phenomena commence at the spirit-end4 ,in animals all commence at the matter-end1 and by automatic response terminate in the same4 ,man alone lives in both worlds1 partakes of both natures1 and acts according to either method4 ,the more we reflect on this subject1 the more we shall be convinced that completed spirit individuality explains1 as nothing else can1 all that is characteristic of man4 ,it is this which constitutes person1 or the self-acting ego4 ,it is this which constitutes self-consciousness1 free-will1 and moral responsibility4 ,and out of these1 again1 grows1 the recognition of relations to other moral beings and to ,god1 and therefore ethics and religion4 ,out of these1 also1 grows the capacity of indefinite voluntary progress4 ,this also means separate life1 spirit-viability1 or immortality4 ,self-consciousness especially seems to me the simplest sign of separate entity or spirit-individuality1 and its appearance among psychical phenomena the very act of spirit-birth4 ,we may imagine man to have emerged ever so gradually from animals3 in this gradual development the moment he became conscious of self1 the moment he turned his thoughts inward in wonder upon himself and on the mystery of his existence as separate from ,nature1 that moment marks the birth of humanity out of animality4 ,all else characteristic of man followed as a necessary consequence4 ,i am quite sure that1 if any animal1 say a dog or a monkey1 could be educated up to the point of self-consciousness 7which1 however1 ,i am sure is impossible71 that moment he 7no longer it7 would become a moral responsible being1 and all else characteristic of moral beings would follow4 ,at that moment would come personality1 immortality1 capacity of voluntary progress2 and science1 philosophy1 religion1 would quickly follow4 ,we have emphasized self-consciousness as the most fundamental sign of spirit-individuality2 but a difference of exactly the same kind is found running through the whole gamut of human faculties as compared with corresponding faculties in animals4 ,as animal consciousness is related to human self-consciousness1 so exactly is animal will to human free-will1 animal intelligence to human reason1 animal sign-language to rational grammatical speech of man1 constructive art of animals to true rational progressive art of man4 ,in every one of these the resemblance is great1 but the difference is immense1 and not only in degree but also in kind4 ,in every case it is like shadow and substance1 promise and fulfillment1 or1 still better1 it is like embryo and child4 ,the change from one to the other is like to a birth into a higher sphere1 the beginning of another cycle of evolution4 ,we would like to follow this idea out in detail1 but it would lead us beyond the scope of this work4 ,those who desire to do so we would refer to an article by the author on the 8,psychical ,relation of ,man to ,animals40#dd ,but it will be objected that there are other births of energy from lower to higher condition2 but such births do not insure continued existence in the higher condition4 ,in the gradual evolution of energy described on page #caf1 when a portion rises from physical to chemical1 from chemical to vital1 or from vital to sentient1 it does not remain ever after in the higher condition--there is no immortality on the higher plane4 ,on the contrary1 all these lower forms of energy are continually ascending and descending2 transformation is downward as well as upward4 ,why should there be an exception in this last birth8 ,in these successive upward metamorphoses of energy why should the last only be permanent8 ,i answer3 ,because it reaches at last its final goal1 viz41 complete individuation1 as free1 self-acting spirit2 it reaches again the spiritual plane from which it sprang1 and becomes thereby a partaker of the ,divine nature2 because it comes at last into moral relations with the absolute--the ,divine--and therefore above the plane of shifting changes4 ,if the scale of energy be likened to a ladder with many rounds1 reaching from the plane of matter to the plane of spirit1 then so long as energy is on the ladder it ascends and descends2 but1 once it reaches the plane of free spirit1 it is in a wholly new world in which eternal ascent is the law4 ,perhaps ,i can best bring out the reasonableness of my view by comparing it with other possible alternative views4 ,there are three possible views as to the nature1 the origin1 and the destiny of the human spirit3 7#a47 ,that it pre-existed always--uncreated1 underived1 eternal1 both ways--backward as well as forward4 ,therefore1 as it never began1 so it will never end4 ,it is immortal of its own right4 ,this is substantially the view of ,plato1 of ,leibnitz1 and perhaps some other philosophers4 7#b47 ,that it is derived from ,god directly--created at once without natural process2 that at the moment of creation of the first man ,adam1 and at some unknown time and in some inscrutable way in the history of each individual1 it was injected into the body from the outside1 and at the same time endowed with immortality4 ,this1 ,i take it1 is the orthodox view4 7#c47 ,that it was indeed derived from ,god1 but not directly2 created indeed1 but only by natural process of evolution2 that it indeed pre-existed1 but only as embryo in the womb of ,nature1 slowly developing through all geological times1 and finally coming to birth as living soul in man4 ,thus it attains immortality at a certain stage of development1 viz41 at spirit-birth4 ,this is the view ,i have striven to enforce4 ,i hold up these three views3 ,which is the more rational8 ,the view of ,plato--that of self-existent1 uncreated1 eternal spirit--,i think few will entertain at this time of the world's day4 ,the usual orthodox view ,i have shown is surrounded with insuperable difficulties2 is wholly unscientific and irrational4 ,what is there left but the view presented above8 ,plato is right in asserting pre-existence1 but wrong in denying creation4 ,the usual view is right in asserting creation1 but wrong in denying natural process4 ,the view ,i have presented asserts pre-existence in embryo and creation by natural process4 ,it therefore combines and reconciles the two extreme views1 and is more rational than either4 ,some ,general ,conclusions4--,there are still two or three thoughts so closely connected with what we have already said that we can not pass them over3 #a4 ,we have seen that every mental state corresponds with a particular brain state1 and every mental change with a brain change4 ,we have1 therefore1 here1 two series1 physical and psychical1 corresponding with each other1 term for term4 ,for every change in the one there is a corresponding change in the other1 both in kind and amount4 ,now1 is not this the test of the relation of cause and effect8 ,it certainly is4 ,yes1 there must be a causal relation here1 even though we are not able to understand the nature of the causal nexus4 ,but which is cause and which effect8 ,if the view above presented be correct1 then in animals brain changes are in all cases the cause of psychical phenomena4 ,in man alone1 and only in his higher activities1 psychic changes precede and determines brain changes4 ,in man alone brain changes are determined not only by external but by internal impressions4 ,man alone perceives not only objects--material things--but also relations and properties abstracted from the objects1 i4 e41 ideal things2 and1 moreover1 not only relations between objects1 but also relations between relations or ideas4 ,in man alone there is an inner world--microcosm--the things of which are thoughts1 ideas1 etc4 ,this self-acting power of spirit on the things of itself1 instead of merely reacting as played upon by external nature1 is characteristic of man1 and is a necessary result and a sign of severance1 partial at least1 of physical bond with ,nature4 #b4 ,again1 ,i have used the term vital principle4 ,i must justify it4 ,i know full well that it is the fashion to ridicule the term as a remnant of an old superstition which regards vital force as a sort of supernatural entity unrelated to other forces of ,nature4 ,no one has striven more earnestly than myself to establish the correlation of vital with physical and chemical forces2#de and yet1 if the view above presented be true1 there is a kind of justification even for the term vital principle--much more1 vital force4 ,there is a kind of reason and true insight in the personification of the forces of ,nature1 and especially of vital force4 ,all forces1 by progressive dynamic individuation1 are on the way toward entity or personality1 but fully attain that condition only in man4 #c4 ,again1 to perceive relations and properties abstracted from material things1 to form abstract or general ideas1 to form not only percepts but also concepts1 is admitted to be a characteristic of man--a characteristic on which all our science and philosophy rest4 ,from time immemorial the vexed question has been debated1 8,have such abstract or general ideas any real existence1 or are they mere names of figments of the mind80 ,this is the famous question of realism and nominalism4 ,now1 if our view be correct1 then there is one most fundamental abstraction1 viz41 self1 which is indeed a reality4 ,self-consciousness is the direct recognition of the one reality1 spirit1 of which all others are the sign and shadow--the true reality which underlies and gives potency to all abstractions or ideas4 ,do we not find in this view1 then1 the foundation of a true realism1 or rather a complete reconciliation of realism and nominalism8 #d4 ,thus1 then1 ,nature1 through the whole geological history of the earth1 was gestative mother of spirit1 which1 after its long embryonic development1 came to birth and independent life and immortality in man4 ,is there any conceivable meaning in ,nature without this consummation8 ,all evolution has its beginning1 its course1 its end4 ,without spirit-immortality this beautiful cosmos1 which has been developing into increasing beauty for so many millions of years1 when its evolution has run its course and all is over1 would be precisely as if it had never been--an idle dream1 an idiot tale signifying nothing4 ,i repeat3 ,without spirit-immortality the cosmos has no meaning4 ,now mark3 ,it is equally evident that1 without this gestative method of creation of spirit1 the whole geological history of the earth previous to man would have no meaning4 ,if man's spirit were made at once out of hand1 why all this elaborate preparation by evolution of the organic kingdom8 ,the whole evolution of the cosmos through infinite time is a gestative process for the birth of spirit--a divine method of the creation of spirits4 ,thus1 again1 man is born of ,nature into a higher nature4 ,he therefore alone is possessed of two natures--a lower1 in common with animals1 and a higher1 peculiar to himself4 ,the whole mission and life-work of man is the progressive and finally the complete dominance1 both in the individual and in the race1 of the higher over the lower4 ,the whole meaning of sin is the humiliating bondage of the higher to the lower4 ,as the material evolution of ,nature found its goal1 its completion1 and its significance in man1 so must man enter immediately upon a higher spiritual evolution to find its goal and completion and its significance in the ideal man--the ,divine man4 ,as spirit1 unconscious in the womb of ,nature1 continued to develop by necessary law until it came to birth and independent life in man1 so the new-born spirit of man1 both in the individual and in the race1 must ever strive by freer law to attain1 through a newer birth1 unto a higher life4 ,,chapter ,v4 ,,the ,,relation ,,of ,,god ,,to ,,man4 ,in the two preceding chapters we have discussed the relation of ,god to ,nature and of man to ,nature4 ,there is still another relation1 if possible1 of still more vital importance to us1 viz41 the relation of ,god to man4 ,this1 of course1 introduces the question of revelation--a subject which ,i approach with some reluctance4 ,i feel ,i am treading on holy ground1 and must do so with shoes removed4 ,if it be asked1 ,how is evolution concerned with the subject of revelation8 ,i answer ,evolution emphasizes and enforces the reign of law taught by all science1 and makes it at last universal4 ,many conclude1 therefore1 that1 if evolution be true1 a belief in the possibility of any form of revelation is irrational4 ,i do not think this follows1 and ,i will give my reasons4 ,i do so1 however1 very briefly1 because we are not yet ready to formulate our views except in the most general way4 ,if man be indeed something more than a higher species of animal2 if man's spirit be indeed a spark of ,divine energy individuated to the point of self-consciousness and recognition of his relation to ,god2 if spirit embryo1 developing in the womb of ,nature through all geological time1 came to birth and independent spirit-life in man1 and thus man alone is a child of ,god as well as a product of ,nature--if all this be true1 then it is evident that this wholly new relation requires also a wholly different mode of ,divine operation4 ,if ,god operates on ,nature only by regular processes1 which we call natural laws1 then he must operate on spirit in a different and a more direct way1 and this we call revelation4 ,if to the student of ,nature it is inconceivable that ,he should operate on ,nature except by natural laws 7for this is the name we give to ,his chosen mode of operation there71 then to the student of theology it is equally inconceivable1 if our view of man be true1 that ,he should not operate on spirit in some more direct and higher way1 i4 e41 by revelation4 ,but some will ask1 ,is not this a palpable violation of law8 ,i think not4 ,all divine operations are1 must be1 according to reason1 i4 e41 according to law4 ,the operation of the divine on the human spirit1 i4 e41 revelation1 must therefore be according to law1 but a higher law than that which governs ,nature1 and1 therefore1 from the point of view of ,nature1 supernatural4 ,there is nothing wholly unique in this4 ,life is a higher form of force than the physical and chemical4 ,life-phenomena are therefore super-physical1 and if we confined the term ,nature to dead ,nature they would be supernatural4 ,so the free1 self-determined acts of spirit on spirit1 even of the spirit of man on the spirit of man1 much more of the ,spirit of ,god on the spirit of man1 may be according to law1 and yet from the natural point of view be supernatural4 ,it is true that1 in the complex of phenomena1 material and spiritual inextricably woven together1 which go to make up human life1 ,science must ever strive to reduce as much as possible to material laws1 for this is her domain1 and she is bound to extend it2 but1 if our view of man be true1 there will always remain a large residuum of phenomena--a whole world of phenomena--which will never yield1 because clearly beyond her domain4 ,standing on the lower material plane1 these phenomena are wholly super-material1 and therefore incomprehensible from the material point of view4 ,we must rise and stand on the higher plane before these also are reduced to law1 but a higher law than that operating on the lower plane4 ,if1 therefore1 science insists on banishing the supernatural from the realm of ,nature1 theology may reasonably insist on its necessity1 in this sense1 in the realm of morals and religion4 ,if1 then1 the direct influence of the ,spirit of ,god on the spirit of man be what we call revelation1 then there is evidently no other kind of revelation possible2 and1 furthermore1 such revelation is given to all men in different degrees4 ,it is given to all men as conscience2 in greater measure to all great and good men as clearer perception of righteousness2 in pre-eminent measure to ,hebrew prophets and ,christian apostles2 but supremely and perfectly to ,jesus alone4 ,but there is1 and in the nature of things there can be1 no test of truth but reason4 ,we must fearlessly1 but honestly and reverently1 try all things1 even revelations1 by this test4 ,we must not regard1 as so many do1 the spirit of man as the passive amanuensis of the ,spirit of ,god4 ,revelations to man must of necessity partake of the imperfections of the medium through which it comes4 ,as pure water from heaven1 falling upon and filtering through earth1 must gather impurities in its course differing in amount and kind according to the earth1 even so the pure divine truth1 filtering through man's mind1 must take imperfections characteristic of the man and of the age4 ,such filtrate must be redistilled in the alembic of reason to separate the divine truth from the earthy impurities4 ,,chapter ,,vi4 ,,the ,,objection1 ,,that ,,the ,,above ,,view ,,implies ,,pantheism1 ,,answered4 ,it will be observed that the views presented in the last three chapters are closely connected with one another1 and all conditioned on the 8,relation of ,god to ,nature10 urged in ,chapter ,,iii4 ,now it will doubtless be objected to this view1 especially as applied in ,chapter ,,iv on the 8,relation of ,man to ,nature10 that it is naught else than pure pantheism2 that it destroys completely the personality of ,deity1 and with it all our hopes of communion with him1 and all our aspirations of love and worship toward him2 that1 according to this view1 ,god becomes only the soul or animating principle of ,nature1 operating everywhere but unconsciously like the vital principle of an organism2 that the whole cosmos becomes in fact a great organism1 developing under the operation of resident force according to necessary law1 only that we apotheosize this omnipresent force and call it ,god2 and finally1 that ,god is naught else than an abstraction1 created like other abstractions or general ideas wholly by the human mind1 and having no objective existence4 ,furthermore1 it will be said1 that according to this view1 this omnipresent unconscious energy individuates itself by necessary law of evolution more and more until it reaches1 for the first time in man1 self-consciousness and immortality1 and thus that man himself is the only self-conscious immortal being in existence1 and therefore the only being worthy of reverence and worship4 ,thus1 this view leads to humanity-worship or rather to self-worship4 ,i feel the full force of this objection4 ,i answer it as follows3 ,i freely admit that1 following up this scientific line of thought alone1 we are carried strongly in the direction of pantheism4 ,but there is nothing strange or exceptional in this4 ,in all the deepest questions1 single lines of thought inevitably carry us to extreme one-sided views4 ,this seems to be the necessary result of the essentially two-fold nature of man1 self-conscious spirit in a material body1 the relation between which is1 and must ever be1 inscrutable4 ,on this account there is and must be a fundamental antithesis in human philosophy1 i4 e41 two lines of thought1 the material and spiritual1 which lead to two apparently irreconcilable views4#df ,we have already seen that a rational philosophy1 whenever we are able to reach such1 is always found in a higher and more comprehensive view1 which includes1 combines1 and reconciles two one-sided1 partial1 and mutually excluding views4 ,but spirit and matter1 or mind and brain1 or ,god and ,nature1 is the fundamental antithesis which underlies and is the cause of all other lesser antitheses4 ,this antithesis1 therefore1 is absolutely fundamental1 and therefore forever irreconcilable4 ,we must accept both sides1 even though we can not clearly perceive the nature of their relation4 ,we must be content with compromise where we can not effect complete reconciliation4 ,we must frankly acknowledge that the antagonism is apparent only1 and the result of the limitation of our faculties1 and believe that1 if we could only rise to a high enough point of view1 like all other antitheses1 this also would disappear in a rational philosophy4 ,now1 to apply these principles4 ,no one1 we admit1 can form a clear conception of how immanence of ,deity is consistent with personality1 and yet we must accept both1 because we are irresistibly led to each of these by different lines of thought4 ,science1 following one line of thought1 uncorrected by a wider philosophy1 is naturally led toward the one extreme of pantheistic immanence2 the devout worshiper1 following the wants of his religious nature1 is naturally led toward the other extreme of anthropomorphic personality4 ,the only rational view is to accept both immanence and personality1 even though we can not clearly reconcile them1 i4 e41 immanence without pantheism1 and personality without anthropomorphism4 ,we have already seen in the third chapter1 how following the scientific line of thought1 we are logically driven to immanence4 ,we wish now to show how1 following another line of thought1 we are as logically driven to personality4 ,on this most difficult subject1 however1 all we are prepared to do is to throw out some brief suggestions1 in the hope that they may be carried out more perfectly by some thoughtful reader2 scatter some seed-thoughts1 in the hope that1 falling haply on good soil1 they may spring up and bear more fruit than ,i have been able to produce4 #a4 ,in the gradual individuation of the universal ,divine energy described in ,chapter ,,iv1 there must of course be a corresponding growth of a kind of independent self-activity which reaches completeness in man1 and in fact constitutes what we call self-consciousness and free will4 ,the exact nature of the relation of ,deity or of the general forces of ,nature to this gradually individuated portion1 ,i do not undertake to define4 ,and how this idea of partial self-activity comports with the absoluteness of ,deity we can not clearly understand4 ,but this fact need not specially disturb us here2 for this is only one branch of the wider question of the moral agency of man in relation to the absolute sovereignty of ,god1 or the freedom of man in relation to necessary law in ,nature4 #b4 ,personality behind ,nature4--,we have already shown that1 if the brain of a living1 thinking man were exposed to the scrutiny of an outside observer with absolutely perfect senses1 all that he would or could possibly see would be molecular motions1 physical and chemical4 ,but the subject himself1 the thinking1 self-conscious spirit1 would experience and observe by introspection only consciousness1 thought1 emotion1 etc4 ,on the outside1 only physical phenomena2 on the inside only psychical phenomena4 ,now1 must not the same be necessarily true of ,nature also8 ,viewed from the outside by the scientific observer1 nothing is seen1 nothing can be seen1 there is nothing else to be seen1 but motions1 material phenomena2 but behind these1 on the other side1 on the inside1 must not there be in this case also psychical phenomena1 consciousness1 thought1 will2 in a word1 personality8#dg ,in the only place where we do get behind physical phenomena1 viz41 in the brain1 we find psychical phenomena4 ,are we not justified1 then1 in concluding that in all cases the psychical lies behind the physical8 ,the human brain is a wonderful instrument1 by means of which1 in some inscrutable way1 viz41 in our own experience1 we do get behind1 on the other side1 on the inside of some material phenomena1 and in so far become partakers of the ,divine nature4 ,but behind other phenomena of ,nature we may never hope to penetrate either by observation or experience1 but only in dim way by highest reason4 ,science1 even in the case of the brain1 can not pass from the one kind of phenomena to the other4 ,if she would study the inside she must abandon the outside--she must abandon the microscope and take to introspection4 ,if she would study the phenomena of the higher platform1 she must leave the lower and climb up and stand on the higher4 ,if this be true of the brain where the two kinds of phenomena are brought so close together1 how much more is it true of the phenomena of the cosmos4 ,we can never hope1 either by observation or by experience1 to pass beyond the veil4 ,we must abandon the methods of science and reach it1 if at all1 in some other way4 ,not the clear-sighted but the pure-hearted shall see ,god in ,nature4 ,thus1 then1 we see that our own self-conscious personality behind brain phenomena compels us to accept consciousness1 will1 thought1 personality behind ,nature4 ,now ,i assert that1 once get this abstract idea in the mind1 and by a necessary law of thought it gradually expands without limit1 and eventually reaches the form of infinite consciousness1 will1 thought1 etc41 and therefore of an infinite person4 ,this law of indefinite expansion may be illustrated by the ideas of space and time4 ,the animal1 and1 indeed1 the infant1 understands space and time only in their relation to itself1 but has not yet abstracted these from their contents4 ,this comes only with the birth of self-conscious personality4 ,but1 so soon as the abstract idea of space is acquired1 by a necessary law of mental activity it expands without limit1 and finally becomes the idea of infinite space4 ,similarly1 so soon as the idea of time as abstracted from its contents is conceived1 it inevitably expands without limit and grows into the idea of infinite time4 ,so is it precisely with the idea of self-conscious personality4 ,the animal or the very young child is indeed conscious of its body and of external objects in their mutual relations1 but not of self1 as abstracted from its contents4 ,the animal never attains it1 the child does4 ,now1 so soon as this idea of self-conscious personality--of a spiritual entity underlying material phenomena--appears1 by a necessary law of mental activity it expands without limit1 and inevitably reaches the idea of an infinite self1 an infinite person1 ,god1 behind the phenomena of ,nature4 ,but some will object that this idea of infinite personality is inconceivable4 ,true enough2 but the opposite is far more inconceivable4 ,the ideas of infinite space and infinite time are also inconceivable1 yet we must accept them1 because the idea of all space or all time being limited is still more inconceivable2 for if we think of space or time as limited1 immediately there comes the question1 8,what is there beyond the limit80 ,there is therefore this wide difference between these two inconceivables3 the one is so only in the sense of transcending the power of our mind1 but the other is unthinkable1 self-contradictory1 absurd4 ,so also is it with self-conscious personality4 ,the idea of an infinite self1 i4 e41 ,god1 is indeed inconceivable1 but only in the sense of transcending our power of comprehension2 but the idea of the consciousness behind the cosmos as being limited or finite is more than inconceivable1 it is unthinkable1 self-contradictory1 absurd2 for immediately comes the question1 8,what is there beyond which limits it80 ,to the ,greek mind ,zeus was limited2 therefore of necessity came also the idea of ,fate1 superior to and limiting ,zeus himself4 ,to them1 therefore1 ,fate was the real ,god--the absolute4 #c4 ,divine ,personality4--,i have used the word personality as expressing the nature of ,god4 ,but let me not be misunderstood4 ,i well know we can not conceive clearly of an infinite1 unconditioned personality4 ,deeply considered1 it seems nothing short of a contradiction in terms4 ,all ,i insist on is this3 ,in our view of the nature of ,god1 the choice is not between personality and something lower than personality1 viz41 an unconscious force operating ,nature by necessity1 as the materialists and pantheists would have us believe2 but between personality as we know it in ourselves and something inconceivably higher than personality4 ,language is so poor that we are obliged to represent even our mental phenomena by physical images4 ,how much more1 then1 the ,divine nature by its human image6 ,self-conscious personality is the highest thing we know or can conceive4 ,we offer him the very best and truest we have when we call him a ,person2 even though we know that this1 our best1 falls far short of the infinite reality4 #d4 ,cause in ,nature4--,we have thus far spoken only or principally of self-consciousness1 but the same precisely is true of another essential attribute of personality1 viz41 free-will4 ,every one admits causative force or forces operating in ,nature4 ,science has shown that all the different kinds of force are but different forms of one omnipresent energy4 ,now1 looking abroad on ,nature from the outside1 this omnipresent energy seems to modern science as simply resident1 inherent in matter itself1 and therefore as operating unconsciously and by necessity4 ,but the question occurs1 8,whence did we get the idea of force1 energy1 causation80 ,i answer unhesitatingly3 ,we get it not from without by observation of ,nature1 but from within through consciousness2 not from the outside view1 but from1 the inside view of phenomena4 ,we can not conceive of phenomena without force1 of effects without cause1 because we are intensely conscious of being ourselves through our wills an active cause of external phenomena4 ,if we were merely passive observers1 not active causers of changes in the external world1 then these external phenomena would seem to us merely to shift and change and succeed each in a certain order4 ,we might note the order and determine the laws of sequence1 and thus form a science2 but it would never enter into our minds to imagine any causal or dynamical nexus between them4 ,in the mind of such passive observer1 but not doer--thinker1 but not worker--would be completely realized the only thorough-going and consistent materialistic philosophy1 i4 e41 a philosophy in which1 like ,comte's1 cause and force have no place--are in fact banished as a superstition from science4 ,but the clear consciousness of essential energy1 of causative force within1 the certainty that we ourselves1 through our wills and by the conscious exertion of force do determine changes in the external world1 compels us to attribute all changes to causative force of some kind1 and naturally enough1 until the interference of science1 to a personal will like our own4 ,thus by a necessary law we project our internal states into external ,nature4 ,but see now the steps of evolution of this idea4 ,at first1 i4 e41 in the uncultured races1 and also in childhood1 external forces take the form of a personal will like our own residing in each object1 and controlling its phenomena as our wills control our bodily movements 7fetichism74 ,then1 as culture advances1 it takes next the form of several personal wills controlling each the phenomena of a different department of ,nature 7polytheism74 ,finally1 in the highest stage of culture1 it takes the form of one personal will controlling the phenomena of the whole cosmos 7monotheism74 ,to the religious but unscientific mind in all these stages the personal will is anthropomorphic4 ,but we have already seen 7,chapter ,,iii7 how anthropomorphism has been driven by science from one department after another1 until now at last by evolution it is driven out of ,nature entirely1 and to those following this line of thought alone1 the phenomena of ,nature are relegated to forces inherent in matter1 and operating by laws necessary and fatal2 and not only so1 but material forces are made to invade even the realm of consciousness1 and reduce this also to material laws4 ,thus the savage ejects his own conscious personal will into every separate object of ,nature2 the modern materialist injects material forces into the realm of consciousness4 ,but1 as already seen1 a rational philosophy admits these two antithetic views1 and strives to combine and reconcile them4 ,this reconciliation1 as far as it is possible for us1 is found in a personal will immanent in ,nature1 and determining directly all its phenomena4 ,thus it is evident that the idea of a causal nexus between successive phenomena is a primary conception1 and therefore ineradicable and certain4 ,even from the purest evolution point of view it must be true1 for1 if man's mind grew out of the forces of ,nature1 this idea must represent a fact in ,nature4 ,also1 analysis shows that all causative force originates in will4 ,lastly1 culture and reason1 by a necessary law of expansion1 carry us upward to the conception of one infinite sustaining and creative will4 ,science may sometimes obscure but can not destroy this idea4 ,evolution1 which was supposed by some to have destroyed it for ever1 has only temporarily obscured it in the minds of the unreflecting1 by the supposed identity of evolution with materialism4 ,from this temporary eclipse it now emerges with still greater clearness and far greater nobleness4 ,for1 observe3 ,all the effects known to us in ,nature are finite2 therefore a personal will1 which determines these separately by successive acts1 as we do1 must also be finite like ourselves4 ,but a will1 which by one eternal act ever-doing1 never done1 determines the evolution and the sustentation of an infinite cosmos1 must itself be infinite4 ,thus only in the doctrine of universal evolution do we rise to a just conception of ,god as an infinite cause4 #e4 ,design in ,nature4--,as the idea of cause and force is related to will1 so precisely is the idea of design related to thought4 ,we get this also1 not from without1 but from within4 ,adaptation of means to ends is in our experience the result of thought1 and we can not conceive it to result otherwise4 ,the effect of science can not be to destroy this primary conception--which1 indeed1 like all primary conceptions1 is ineradicable1 and already more certain than anything can be made by proof--but only to exalt and purify our conceptions of the designer4 ,for1 observe3 ,in any case of adaptive structure1 whether in the animal body or in planetary relations1 the evidence of design is not in the materials1 but in the use of the materials2 not in the parts1 but in the adjustment of the parts for a purpose4 ,design1 purpose1 adjustment1 adaptation1 are not material things1 but relations or intellectual things1 and therefore perceivable only by thought1 and conceivable only as the result of thought4 ,it is simply impossible to talk about such adaptive structures without using language which implies design4 ,the very word 8adaptive0 implies it4 ,it is impossible even to think of such structures without implicitly assuming intelligence as the cause4 ,it makes no particle of difference how the material originated1 or whether it ever originated at all2 it matters not whether the adaptation was done at once out of hand1 or whether by slow process of modification2 it matters not whether the adaptive modification was brought about by a process of natural selection1 or by pressure of a physical environment2 whether without law or according to law4 ,the removal of the result from man-like directness of separate action can not destroy the idea of design1 but only modify our conception of the ,designer4 ,what science1 and especially evolution1 destroys1 therefore1 is not the idea of design1 but only our low anthropomorphic notions of the mode of working of the ,designer4 ,precisely the same change takes place here under the influence of science as has taken place in all our notions concerning ,god4 ,the uncultured savage sees a separate god in every object4 ,as culture advances1 his gods become fewer and nobler1 until1 in the most advanced states1 man recognizes but one infinite ,god1 the creator and sustainer of all4 ,god is still in every phenomenon1 but no longer as a separate ,god1 but only as the separate manifestation of the ,one4 ,thus culture takes away our gods1 but only to compel us to seek him in nobler forms until we reach the only true ,god4 ,but1 even after the conception of the one ,god is reached1 how many seem to regard him as altogether such a one as ourselves2 but science shows us that his ways are not like our ways1 nor his ends as our ends4 ,thus science1 more than all other kinds of culture1 simplifies while it infinitely ennobles and purifies our conceptions of ,deity4 ,again1 the same change takes place in our sense of mystery4 ,i suppose most people imagine that it is the special mission of science to destroy all mystery4 ,many seem to think that superstition1 or even religion1 is inseparably connected with ignorance and mystery1 and all must disappear together before the light of science4 ,but not so4 ,there is only a gradual progressive change--an evolution in the form of mystery as well as in the form of religion4 ,to the savage everything is a separate mystery4 ,the function of science is1 indeed1 to destroy these separate mysteries1 by explaining them2 but1 in doing so1 it only reduces them to fewer and grander mysteries1 and these again to still fewer and grander1 until1 in an ideally perfect science1 all separate and partial mysteries are swallowed up in the one all-embracing infinite mystery--the mystery of existence4 ,there is still mystery in each object1 but no longer a separate mystery--only a separate manifestation of the one overwhelming mystery4 ,or1 again1 and finally3 ,the same change occurs in our ideas of creation4 ,at first every object is a separate creation--a manufacture4 ,with advancing science these separate1 creative acts become fewer and nobler1 until now1 at last1 in evolution1 all are embraced and swallowed up in one eternal act of creation--a never-ceasing procession of the divine energy4 ,every object is still a creation1 but not a separate creation--only a separate manifestation of the one continuous creative act4 ,now1 precisely the same change must take place in our conception of design in ,nature4 ,to the uncultured there is a distinct and separate design in every separate work of ,nature4 ,but1 as science advances1 all these distinct1 separate1 petty1 man-like designs are merged into fewer and grander designs1 until1 finally1 in evolution at last1 we reach the conception of the one infinite1 all-embracing design1 stretching across infinite space1 and continuing unchanged through infinite time1 which includes and predetermines and absorbs every possible separate design4 ,there is still design in everything1 but no longer a separate design--only a separate manifestation of the one infinite design4 ,thus1 then1 our own self-consciousness and will and thought give rise1 necessarily1 to the conception of an infinite self-consciousness1 will1 and thought--i4 e41 ,god4 ,the necessity to believe in self-conscious spirit behind bodily phenomena compels us to believe also in an infinite self-conscious spirit behind cosmic phenomena4 ,looking at the operations of this ever-active spirit1 whether in the one case or the other1 from the outside1 it looks like unconscious energy inherent in matter itself1 and therefore like necessity1 or fate4 ,but1 looked at from the inside in the one case1 the brain1 we perceive only self-conscious1 free activity of spirit4 ,therefore1 we are compelled to acknowledge in the other case1 the cosmos1 also1 the same source of all activity1 the same cause of all phenomena4 ,we are compelled to acknowledge an infinite immanent ,deity behind phenomena1 but manifested to us on the outside as an all-pervasive energy4 ,but some portion of this all-pervasive energy again individuates itself more and more1 and therefore acquires more and more a kind of independent self-activity which reaches its completeness in man as self-consciousness and free-will4 ,we said1 8a kind of independent self-activity40 ,how this comports with the absoluteness of ,god we can not understand1 any more than we can understand how it comports with invariable law in ,nature4 ,we simply accept them both as primary truths1 even though we can never hope to reconcile them completely1 because we can not understand the exact nature of the relation of spirit to matter4 ,we can not look at the outside and the inside at the same time4 ,if we could understand the relation of psychical phenomena to brain-changes1 then might we hope to understand far more perfectly than now the relation of ,god to ,nature4 ,but as in the one case1 the brain1 although we can not understand the nature of the relation1 yet we are sure of the intimacy of the connection of the two series1 psychical and physical1 term for term2 so in the other case1 the cosmos1 although we can not understand the exact nature1 we are sure of the intimacy of the connection1 term for term--every material phenomenon and event with a corresponding psychical phenomenon as its cause4 ,,chapter ,,vii4 ,,some ,,logical ,,consequences ,,of ,,the ,,doctrine ,,of ,,the ,,divine ,,immanency4 ,the doctrine of the ,divine immanency carries with it the solution of many vexed questions4 ,in fact1 in its light these questions simply pass out of view as no longer having any significance4 ,several of these questions have been alluded to in an indirect way in the previous chapter and in ,chapter ,,iii4 ,we take them up distinctly here1 and show their relation to evolution4 ,religious thought1 like all else1 is subject to a law of evolution1 and therefore passes through regular stages4 ,of these stages1 three are very distinct and even strongly contrasted4 ,they correspond in a general way to the three stages of ,comte1 which he has misnamed the theological1 the metaphysical1 and the positive4 ,we will illustrate by many examples4 ,i4 ,conception of ,god4 ,this1 the most fundamental conception of all religion1 has passed from a gross anthropomorphism to a true spiritual theism1 and the change is largely due to science and especially to the theory of evolution4 ,there are three main stages in the history of this change3 7#a47 ,the first is a low anthropomorphism4 ,god is altogether such a one as ourselves1 but larger and stronger4 ,his action on ,nature1 like our own1 is direct2 his will is wholly man-like1 capricious and without law4 7#b47 ,the second is still anthropomorphism1 but of a nobler sort4 ,god is not altogether like ourselves4 ,he is man-like2 yes1 but also king-like4 ,he is not present in ,nature1 but sits enthroned above ,nature in solitary majesty4 ,he acts on ,nature1 not directly but indirectly1 through physical forces and natural laws4 ,he is an absentee landlord governing his estate by means of appointed agents1 which are the natural forces and laws established in the beginning4 ,he interferes personally and by direct action only occasionally1 to initiate something new or to rectify something going wrong4 ,this idea culminated and found the clearest expression in the eighteenth century1 and was the necessary result of the scientific ideas then prevalent1 viz41 ideas of pre-established stability of cosmic order and fixedness of organic types4 ,god was the great artificer1 the great architect1 working1 as it were1 on foreign material and conditioned by its nature4 ,he established all things as they are in the beginning1 and they have continued so ever since4 ,this conception still lingers in the religious mind1 and is in fact the prevailing one now4 ,it is a great advance on the preceding1 but1 alas6 it removes ,god beyond the reach of our love4 ,he is the architect of worlds1 the artificer of the eye1 the sovereign ruler of the universe1 but not our ,father4 ,we are his creatures1 his subjects1 but not his children4 7#c47 ,the third and last stage in this development is true spiritual theism4 ,god is immanent1 resident in ,nature4 ,nature is the house of many mansions in which he ever dwells4 ,the forces of ,nature are different forms of his energy acting directly at all times and in all places4 ,the laws of ,nature are the modes of operation of the omnipresent ,divine energy1 invariable because he is perfect4 ,the objects of ,nature are objectified1 externalized--materialized states of ,divine consciousness1 or ,divine thoughts objectified by the ,divine will4 ,in this view we return again to direct action1 but in a nobler1 a spiritual1 ,godlike form4 ,he is again brought very near to every one of us and restored to our love1 for in him we live and move and have our being4 ,in him all things consist1 by him all things exist4 ,this view has been held by noble men in all times1 especially by the early ,greek fathers1 but is now verified and well-nigh demonstrated by the theory of evolution4 ,no other view is any longer tenable4 ,the idea of ,god is of course the most fundamental of all religious ideas1 and a change in this carries with it many other changes4 ,some of these necessary outcomes1 especially the nature1 the origin1 and the destiny of the human spirit1 and its relation to the ,divine spirit1 ,i have already treated in previous chapters4 ,but there are others which flow so directly and obviously that they may be presented in brief space4 ,,ii4 ,question of ,first and ,second ,causes4 ,among the most obvious of these is the question of first and second causes4 ,this distinction1 ,i suppose1 did not exist in early thought4 ,as a popular view1 it was mainly due to the physical science of the eighteenth century4 ,it was a necessary corollary of the idea of ,god as the great architect sitting outside of ,nature and acting on ,nature as on foreign material4 ,according to this view1 ,god is the original and primary cause of all things2 but he delegates his power to secondary forces1 such as gravity1 heat1 electricity1 etc41 which are therefore the immediate causes of phenomena4 ,i believe that most persons hold this view still4 ,but it is now being displaced by the idea of ,god immanent or resident in ,nature as already explained4 ,this view is a complete identification of first and second causes4 ,all causes are mere modes of the first cause4 ,they seem to us secondary1 necessary1 and unconscious only because they act according to invariable law4 ,but law itself is only the mode of operation of a perfect will4 ,thus we have the same three stages of evolution here also3 7#a47 ,first1 all is first cause1 direct1 man-like1 capricious1 lawless4 7#b47 ,then the first cause acts king-like1 indirectly by many appointed agents subject to pre-enacted laws4 ,these agents or secondary causes directly determine all natural phenomena4 7#c47 ,lastly1 come the complete combination and reconciliation of these two4 ,all is by first cause and direct action1 like the first4 ,all is by invariable law like the second1 the law being only the mode of operation of a perfect will4 ,,iii4 ,question of ,general and ,special ,providence4 ,so also providence1 general and special1 is only another phase of the same question and solved in the same way4 ,at first all is special providence--the result of caprice or favoritism and without law4 ,then all or nearly all is general providence operating by invariable law2 but from time to time the general law is broken through for special purposes when necessary4 ,is not this the prevailing view now8 ,lastly1 these two must be combined and reconciled in a third4 ,all is alike general and special3 general--i4 e41 according to law2 special--i4 e41 by direct action4 ,there is no real distinction between the two4 ,the distinction vanishes in the light of a higher view4 ,,iv4 ,the ,natural and the ,supernatural4 ,in precisely the same category falls the question of the natural and the supernatural4 ,the same three stages are evident here also1 and the same solution3 #a4 ,first all is supernatural and lawless1 and ,nature is viewed with stupid wonder and abject fear4 #b4 ,then ,nature is reduced to mechanical laws and made subject to man4 ,wonder and fear give place to indifference and even perhaps to contempt4 ,we practically live without ,god in the world4 ,it requires1 now1 miracles or a violent breaking through of law in order to startle us out of our stupidity and awaken in us a sense of the ,divine presence4 #c4 ,but we must come lastly to a higher philosophy4 ,we must recognize that all is natural and all is supernatural according as we view it1 but none more than another4 ,all is natural--i4 e41 according to law2 but all is supernatural--i4 e41 above ,nature1 as we usually regard ,nature1 for all is permeated with the immediate ,divine presence4 ,wonder in the contemplation of ,nature returns1 or rather exalted reverence and rational worship are given in place of open-mouthed wonder and superstitious fear4 ,once clearly conceive the idea of ,god permeating ,nature and determining directly all its phenomena according to law1 and the distinction between the natural and the supernatural disappears from view1 and with it disappears also the necessity of miracles as we usually understand miracles4 ,in fact1 the word as we usually understand it has no longer any meaning4 ,i must stop a moment to explain1 lest ,i be misunderstood2 and to enforce1 lest it be thought ,i speak lightly4 ,miracle1 in the sense of violation of law1 is simply impossible1 because law is the expression of the essential nature and perfection of ,god4 ,it is as impossible for ,god to perform a miracle in this sense as it is for him to lie1 and for the same reason1 viz41 that it is contrary to his essential nature4 ,in what sense1 then1 is a miracle possible8 ,i answer1 only as an occurrence or a phenomenon according to a law higher than any we yet know4 ,if we define ,nature as phenomena governed by physical and chemical laws and forces1 then life becomes supernatural and miraculous--because higher than ,nature as we define it4 ,if we reduce the phenomena of life to law and include these also in our definition of ,nature but limit it there1 then the free1 self-determined phenomena of reason become supernatural because above our definition of ,nature4 ,there may well be still other and higher modes of ,divine activity1 the law of which we do not and may never understand4 ,these are above our present definition of ,nature1 and therefore to us supernatural or miraculous4 ,but1 even if miracles in the ordinary sense were possible1 is it not evident that the ordinary processes of ,nature are far more wonderful1 more truly ,godlike1 than any such miracle8 ,v4 ,question of ,design in ,nature4 ,so1 again1 the question of design or purpose or mind in ,nature is similarly solved4 ,it has been said1 it is continually now being said1 that evolution has destroyed forever the teleological view of ,nature--i4 e41 the idea of design in ,nature4 ,yes1 if we mean the man-like1 cabinet-making1 watch-making design of ,paley and older writers--a separate petty design for each separate object4 ,it has indeed destroyed this1 but only to replace it by a far nobler conception--a truly ,godlike design1 a design embracing all space and running through all time1 including and absorbing all possible separate designs and predetermining them by a universal law of evolution4 ,or the same question may be put in another way as 8,mind vs4 ,mechanics in ,nature40 ,in the evolution of thought on this subject at first all was mind1 but lawless1 capricious1 like our own4 ,then one department after another of ,nature was reduced to mechanical1 physical1 necessary law1 until all have been or will be or conceivably may be thus reduced1 and mind seems driven out of ,nature entirely4 ,the friends of religion in despair cry out for at least some small corner left for mind4 ,thus ,i find in recent numbers of an ,english scientific periodical1 8,nature10 a discussion concerning mind as one of the factors of evolution4#dh ,is it not amusing1 if it were not so sad8--,god the ,divine mind as one of the factors of evolution6 ,the true solution is very simple4 ,all is mind or none2 so also all is mechanics or none4 ,it is all mind through mechanics4 ,it is all mechanics from the outside2 it is all mind from the inside4 ,to science all is mechanics2 to theology all is mind4 ,it is the duty of philosophy to reconcile these two opposites by the higher view that mechanics is but the mode of operation of the ,divine mind4 ,there is only one form of evolution1 viz41 human progress1 in which mind--but the human1 not the ,divine mind--is one of the factors of evolution4 ,but to think and speak thus of ,god in relation to ,nature is to place him on the human plane4 ,it is gross anthropomorphism4#di ,,vi4 ,question of the ,mode of ,creation4 ,i might multiply examples almost without limit1 of questions the solution of which depends on this one of the relation of ,god to ,nature4 ,i give one more--,creation4 ,the creation of the universe at once--in the beginning--out of nothing--and then rest ever since4 ,this old anthropomorphic idea is now replaced by that of continuous creation--unhasting1 unresting1 by an eternal process of evolution4 ,for if the universal law of gravitation is the ,divine mode of sustentation of the universe1 the no less universal law of evolution is the ,divine process of creation4 ,,chapter ,,viii4 ,,the ,,relation ,,of ,,evolution ,,to ,,the ,,idea ,,of ,,the ,,christ4 ,what think ye of ,christ8 ,this is indeed in many ways a test-question1 and we ought frankly to meet it4 ,i have feared heretofore to touch this question4 ,i now only throw out some brief suggestions--scatter some seed-thoughts4 ,does ,evolution have anything to say on this also8 ,i think it does4 ,this ,i proceed to show3 ,as organic evolution reached its goal and completion in man1 so human evolution must reach its goal and completion in the ideal man--i4 e41 the ,christ4 ,according to this view1 the ,christ is the ideal man1 and therefore--7mark the necessary implication7--and therefore the ,divine man4 ,we are all as men 7as contradistinguished from brutes7--we are all1 ,i say1 sons of ,god2 the ,christ is the well-beloved ,son4 ,we are all in the image of ,god2 he is the express and perfect image4 ,we are all partakers in various degrees of the ,divine nature2 in him the ,divine nature is completely realized4 ,it is not necessary that the ideal man--the ,christ--should be perfect in knowledge or in power2 on the contrary1 he must grow in wisdom and in stature1 like other men2 but he must be perfect in character4 ,character is essential spirit4 ,all else1 even knowledge1 is only environment for its culture4 ,in the dazzling light of modern science we are apt to forget this4 ,character is the attitude of the human spirit toward the ,divine ,spirit4 ,if ,i should add anything to this definition1 ,i would say it is spiritual attitude and spiritual energy4 ,in the ,christ this attitude must be wholly right2 the harmony--the union with the ,divine--must be perfect4 ,this perfect union gives1 of necessity1 also fullness of spiritual energy4 ,now1 ,i wish to show that1 although the ,christ as thus defined must be human--yes1 even more intensely human than any one of us--yet by the law of evolution we ought to expect him to differ from us in an inconceivable degree1 and especially in a superhuman way4 ,this ,i do by a series of illustrations4 ,we have said that the ,christ is the ideal and therefore the ,divine man--that he is the goal and completion of humanity4 ,but in evolution a goal is not only a completion of one stage1 but also the beginning of another and higher stage--on a higher plane of life with new and higher capacities and powers unimaginable from any lower plane4 ,let me illustrate3 #a4 ,as man is the ideal--the goal and completion of animal evolution1 and yet is he also a birth into a higher plane of life--the spiritual2 so the ,christ1 the ideal man1 may be only the goal and completion of human evolution1 and yet is he also a birth into a new and higher plane--the ,divine4 #b4 ,as the human spirit pre-existed in embryo in animals1 slowly developing through all geological times1 until it came to birth and immortality in man1 so the ,divine spirit is in embryo in man in various degrees of development1 and comes to birth and completion of ,divine life in the ,christ4 #c4 ,as animals reached1 finally1 conscious relations with ,god in man1 even so man reaches union with ,god in the ,christ4 ,as man1 the ideal animal1 is a union of the animal with the spiritual2 so the ,christ1 the ideal of human evolution1 is a union of the human and the ,divine4 #d4 ,finally3 ,as with the appearance of man there were introduced new powers and properties unimaginable from the animal point of view1 and therefore from that point of view seemingly supernatural--i4 e41 above their nature--so with the appearance of the ,christ we ought to expect new powers and properties unimaginable from the human point of view1 and therefore to us seemingly supernatural--i4 e41 above our nature4 ,the ,christ as defined above--i4 e41 as the ideal man--is undoubtedly a true object of rational worship4 ,there are two and only two fundamental moral principles1 viz41 love to ,god and love to man4 ,both of these must be embodied in a rational worship4 ,the one must be embodied in the worship of an ,infinite ,spirit--,god2 the other in the worship of the ideal man--the ,christ4 ,but some one will object that1 admitting all this1 it is impossible that the goal1 the ideal1 should appear until the end of the course of evolution4 ,to him ,i answer3 ,this is indeed true of animal evolution1 but not of human evolution4 ,we have already seen 7see p4 #hh et seq47 that there is an essential difference in this regard between these two kinds of evolution4 ,in addition to all the factors of organic evolution1 in human progress there is a new and higher factor added1 which immediately takes precedence of all others4 ,this factor is the conscious voluntary co-operation of the human spirit in the work of its own evolution4 ,the method of this new factor consists essentially in the formation1 and especially in the voluntary pursuit1 of ideals4 ,in organic evolution species are transformed by the environment4 ,in human evolution character is transformed by its own ideal4 ,organic evolution is by necessary law--human evolution is by voluntary effort1 i4 e41 by free law4 ,organic evolution is pushed onward and upward from behind and below4 ,human evolution is drawn upward and forward from above and in front by the attractive force of ideals4 ,thus the ideal of organic evolution can not appear until the end2 while the attractive ideals of human evolution must come--whether only in the imagination or realized in the flesh--but must come somehow in the course4 ,the most powerfully attractive ideal ever presented to the human mind1 and1 therefore1 the most potent agent in the evolution of human character1 is the ,christ4 ,this ideal must come--whether in the imagination or in the flesh ,i say not1 but--must come somehow in the course and not at the end4 ,at the end the whole human race1 drawn upward by this ideal1 must reach the fullness of the stature of the ,christ4 ,but it will be again objected that all ideals are relative and temporary2 that we are in fact drawn onward and upward by many successive ideals1 one beyond another1 in the course4 ,ideals are but mile-stones which we put successively behind us while we press on to another2 they are successive rounds of an infinite ladder which we put successively beneath us while we rise higher4 ,this one also we shall eventually put behind us and pass on4 ,to this ,i have two answers3 ,admitted that in many ways such is the course of progress2 but who has been able to reach this ideal and conceive a higher8 ,when this one is reached and completely realized in our personal character1 it will be time enough to propose another4 ,again1 it is true that in many ways we have advanced and are still advancing by the use of partial ideals2 but this use of partial and relative ideals is itself in only a temporary stage of evolution4 ,at a certain stage we catch glimpses of the absolute moral ideal4 ,then our gaze becomes fixed1 and we are thenceforward drawn upward forever4 ,the human race has already reached a point when the absolute ideal of character is attractive4 ,this ,divine ideal can never again be lost to humanity4 ,,chapter ,,ix4 ,,the ,,relation ,,of ,,evolution ,,to ,,the ,,problem ,,of ,,evil4 ,the problem of evil has tasked the power and baffled the skill of the greatest thinkers in every age4 ,it would be folly in me to imagine that ,i can solve it4 ,its complete solution is probably impossible in the present state of science4 ,yet ,i can not doubt that on this1 as on every important question relating to man1 the theory of evolution will throw new and important light4 ,all ,i can hope to do is to throw out some brief suggestions on the subject4 ,if evolution be true1 and especially if man be indeed a product of evolution1 then what we call evil is not a unique phenomenon confined to man1 and the result of an accident1 but must be a great fact pervading all nature1 and a part of its very constitution4 ,it must have existed in all time in different forms1 and subject like all else to the law of evolution4 ,let us1 then1 trace rapidly some of the steps of this evolution4 #a4 ,external ,physical ,evil in the ,animal ,kingdom4--,as already seen in previous chapters1 the necessary condition of evolution of the organic kingdom is a struggle for life--a conflict on every side1 with a seemingly inimical environment and a survival of only the strongest1 the swiftest1 or the most cunning--in a word1 the fittest4 ,now1 suppose the course of organic evolution finished in the introduction of man1 and from this vantage-ground we look back over the course and consider its result4 ,shall we call that evil which was the necessary condition of the progressive elevation which culminated so gloriously8 ,evil doubtless it seemed to the individual1 struggling animal1 but is this worthy to be weighed in comparison with the evolution of the whole organic kingdom until it culminated in man8 ,is it not rather a good in disguise8 ,i suppose human arrogance may be willing enough to admit it in this case1 where animals only are sufferers4 #b4 ,physical ,evil in ,relation to ,man4--,but organic evolution1 completed in man1 was immediately transferred to a higher plane1 and continued as social evolution2 material evolution is transformed into psychical evolution2 unconscious evolution1 according to necessary law1 to conscious voluntary progress toward a recognized goal1 and according to a freer law4 ,but in this transformation the fundamental conditions of evolution do not change4 ,man also is surrounded on every side with what at first seems to him an evil environment1 against which he must ever struggle or perish4 ,heat and cold1 tempest and flood1 volcanoes and earthquakes1 savage beasts and still more savage men4 ,what is the remedy--the only conceivable remedy8 ,knowledge of the laws of ,nature1 and thereby acquisition of power over ,nature4 ,but increasing knowledge and power are equivalent to progressive elevation in the scale of psychical being4 ,this conflict with what seems an evil environment is1 therefore1 the necessary condition of such elevation4 ,it is not too much to say that1 without this condition1 except for this necessity for struggle1 man could never have emerged out of animality into humanity1 or1 having thus emerged1 would never have risen above the lowest possible stage4 ,now suppose1 again1 this ideal to have been attained--suppose knowledge of physical laws and power over physical forces to be complete--suppose physical nature completely subdued1 put beneath our feet1 and subject to our will1 and1 from the high intellectual position thus attained1 we look back over the whole ground and consider the result4 ,shall that be called evil which was obviously the necessary condition for attaining our then elevated position8 ,evil it doubtless seemed to the individuals who fell1 and still seems to us who now suffer1 by the way in the conflict2 but is physical discomfort or even physical death of the individual to be weighed in comparison with the psychical elevation of the individual1 and especially of the race8 ,evidently1 then1 physical evil even in the case of man is only seeming evil1 but real good4 #c4 ,organic ,evil--,disease4--,but there is a more dreadful form of evil than that which results from external physical nature--an evil far more subtle and difficult to understand1 and therefore to conquer4 ,i mean internal organic evil--disease in its diversified forms and with its attendant weakness and suffering1 inscrutable often in its causes1 insidious in its approaches1 contagious1 infectious1 spreading from house to house1 carrying suffering and death in its course1 and leaving sorrow and desolation behind4 ,is there any remedy which can transmute this evil into good8 ,there is4 ,it is again knowledge--knowledge of the laws1 and power over the forces1 of organic nature4 ,is it not evident that complete knowledge of the laws of health and the causes of disease would put this evil also under our feet8 ,is it not evident that a perfect knowledge of the laws of health1 and a perfect living according to these laws1 would so entirely subdue this evil that men would no longer die except by natural decay or by accident8 ,is it not evident1 also1 that the race will not attain this knowledge unless it be forced upon us by the necessity of avoiding the dread evil of disease8 ,now suppose1 again1 this ideal attained1 suppose this dread evil subdued by complete knowledge1 and again from our elevated intellectual position we look back over the ground4 ,shall we call that evil which was the necessary condition of our intellectual elevation8 ,evil1 doubtless1 it seems to us individuals who have suffered and are still suffering through our ignorance2 but is such individual suffering or even individual death to be weighed against the psychical elevation of the individual and evolution of the race8 ,ought not the individual to be willing to suffer thus much vicariously for the race8 ,is not this seeming evil also a real good8 ,may we not1 then1 confidently generalize8 ,may we not say that all physical evil is good in its general effect--that every law of ,nature is beneficent in its general operation1 and1 if sometimes evil in its specific operation1 is so only through our ignorance8 ,partly by survival of the fittest1 and partly by intelligence1 man1 like other animals1 brings himself in accord with the laws of ,nature1 and thus appropriates the good and avoids the evil1 and ,nature becomes beneficent only4 ,but1 also unlike any other animal1 man by rational knowledge makes the laws of ,nature his servants1 and uses them for his own purposes1 thus increasing his power and elevating the plane of his life4 #d4 ,moral ,evil4--,but there is still another form of evil1 the most dreadful of all4 ,this one may be called the evil1 in some sense1 the only evil4 ,it is that of which all other forms are but the shadows cast backward and downward along the course of evolution and on lower stages of existence4 ,this consummation of all evil is sin--moral disease--more dreadfully contagious and deadly than any organic disease4 ,what shall we say now8 ,is there any rational explanation of this evil8 ,is there any possible-reason or excuse for an all-wise1 all-powerful ,ruler afflicting man alone of all ,his creatures with this greatest of all evils8 ,in all other cases1 the individual and the race sacrifice themselves for a time physically for the sake of final spiritual elevation2 but this is spiritual debasement4 ,in all other cases1 there is a sacrifice in the course in order to attain the goal1 but this is a missing of the goal itself4 ,is there any view which mitigates this evil1 any philosophic alchemy which can transmute this evil into good8 ,age after age the human mind has prostrated itself in helpless paralysis before this problem4 ,most thinkers have been content to say1 8,thou hast ordered it so4 ,thou art good4 ,it must be right40 ,but many1 and among them some of the best minds1 have said1 8,either ,god is not all-good1 or else not all-wise1 or else not all-powerful1 or else there is no ,god at all40 ,does evolution shed any light on this dread problem8 ,i believe it does4 ,we have said that all other evils are but shadows of this one1 cast backward and downward on earlier stages of evolution and lower forms of existence4 ,but from the evolution point of view these earlier and lower forms of evil are rather to be regarded as foreshadowings of the reality to come4 ,they are but earlier and lower stages of the evolution of the same thing--embryonic conditions of the now full-grown evil4 ,if so1 then the same law must apply here also1 though1 as we shall see1 with a difference4 ,here1 also1 the individual as well as the race finds himself surrounded by what seems an evil environment1 against which he must struggle4 ,the spirit of man is inclosed and conditioned by a lower environment1 which he must subdue or perish4 ,here1 then1 is again a deadly conflict3 8a law in the members warring against the law of the spirit1 and bringing it into captivity02 a law of selfism warring against the law of love1 and bringing it into subjection2 solicitations to debasement on the one hand1 and solicitations to wrong others on the other4 ,how shall it be overcome8 ,what is the remedy8 ,again ,i answer1 ,knowledge of and conformity to the laws of the moral world4 ,but1 as in other cases1 so in this3 this knowledge of and conformity to law1 which is the true goal of humanity1 will not be attained unless it is forced upon us by necessity and in self-defense--i4 e41 by evil4 ,now suppose1 once more1 this knowledge and conformity be complete1 and the ideal of humanity be attained1 and from this final and highest position we look back over the whole ground4 ,shall that be called evil which from the very nature of a moral being and the laws of evolution was obviously the necessary condition of attaining the goal8 ,shall we not from this final position call it a good in disguise8 ,evil1 doubtless1 it seems to us who suffer and stumble and mayhap fall by the way2 but shall the mishap of the individual be weighed as an equivalent against the evolution of the race and the attainment of its goal8 ,ah6 there is the rub4 ,it is all well enough to talk of sacrificing the physical individual to the race1 but not so the spiritual4 ,if we believe in the immortality of the human spirit1 if we do indeed stand related to ,god in the manner explained in ,chapter ,,iv1 then moral evil in the individual has an entirely peculiar and an eternal significance--then the individual human spirit has an infinite worth and can not be sacrificed to the race2 for the evolution of the race itself is only in order to the perfecting of individual human souls4 ,what shall we say now8 ,i answer3 ,the sacrifice is not necessary4 ,there is in the realm of morals alone a way of escape--a saving element which redeems the individual without violating the law4 ,let me explain4 ,it will1 ,i think1 be admitted by all that innocence and virtue are two very different things4 ,innocence is a pre-established1 virtue a self-established1 harmony of spiritual activities4 ,the course of human development1 whether individual or racial1 is from innocence through more or less discord and conflict to virtue4 ,and virtue completed1 regarded as a condition1 is holiness1 as an activity1 is spiritual freedom4 ,not happiness nor innocence but virtue is the goal of humanity4 ,happiness will surely come in the train of virtue1 but if we seek primarily happiness we miss both4 ,two things must be borne steadily in mind3 virtue is the goal of humanity2 virtue can not be given1 it must be self-acquired4 ,now we have already seen that in all evil the remedy1 which not only cures it but transmutes it into good1 is knowledge of law and conformity of conduct thereto--a true science and a successful art--in a word1 knowledge of the laws of ,god and obedience to these laws4 ,in the physical world ignorance of these laws is necessarily fatal1 but not so in the moral world4 ,ignorance here is not necessarily fatal though dangerous4 ,by the very nature of a moral being1 the essential thing is not knowledge but character or virtue--the will to know and the effort to obey4 ,in the physical realm1 knowledge is the goal2 in the moral realm1 knowledge is only in order to virtue4 ,therefore1 in the case of the individual struggling with moral evil within and without1 the victory is always in his power4 ,if he fails1 it is his own fault4 ,his utmost effort in this field must be successful1 because the result is not external1 but internal and in the realm of moral freedom4 ,the spirit of man is self-acting and in some sense1 though not absolutely1 self-existing1 and can not be ruined except by its own act4 ,in the moral world1 where the goal is not knowledge but character1 attainment must be in proportion to honest endeavor in the right spirit4 ,evil1 then1 has its roots in the necessary law of evolution4 ,it is a necessary condition of all progress1 and pre-eminently so of moral progress4 ,but some will ask1 8,why could not man have been made a perfectly pure1 innocent1 happy being1 unplagued by evil and incapable of sin80 ,i answer3 ,the thing is impossible even to omnipotence1 because it is a contradiction in terms4 ,such a being would also be incapable of virtue1 would not be a moral being at all1 would not in fact be man4 ,we can not even conceive of a moral being without freedom to choose4 ,we can not even conceive of virtue without successful conflict with solicitations to debasement4 ,but these solicitations are so strong and so often overcome us1 that we are prone to regard the solicitations themselves as essential evil instead of our weak surrender to them4 ,all evolution1 all progress1 is from lower to higher plane4 ,from a philosophic point of view1 things are not good and evil1 but only higher and lower4 ,all things are good in their true places1 each under each1 and all must work together for the good of the ideal man4 ,each lower forms the basis and underlying condition of the higher2 each higher must subordinate the lower to its own higher uses1 or else it fails of its true end4 ,the physical world forms the basis and condition of the organic1 yet the organism rises to a higher plane only by ceaseless conflict with and adaptation to the physical environment1 which therefore seems in some sense evil4 ,the organic world in its turn underlies and conditions and nourishes the rational moral world4 ,as the senses are the necessary feeders of the intellect1 so the appetites are the necessary feeders of the moral nature4 ,yes1 even the lowest sensual appetites are the necessary basis and nourishers of our highest moral sentiments4 ,and yet the struggle for mastery of the higher spiritual with the lower animal is often so severe that the latter seems to many as essential evil to be extirpated1 instead of a useful servant to be controlled4 ,this view is asceticism4 ,now the whole view of evil usually held is a kind of asceticism1 and therefore1 like asceticism1 must be only a transition phase of human thought4 ,all that we call evil both in the material and the spiritual world is good1 so long as we hold it in subjection as servants to the spirit1 and only becomes evil when we succumb4 ,all evil consists in the dominance of the lower over the higher2 all good in the rational use of the lower by the higher4 ,asceticism may1 indeed1 be the best philosophy for some4 ,if we can not subdue the lower nature1 we must try to extirpate it1 and thus at any cost set free the higher from humiliating bondage4 ,if we can not practice the higher virtue of temperance in all things1 we must even try the lower virtue of total abstinence in some things4 ,if our right eye offends1 we must not hesitate to pluck it out2 but let us not imagine that one eye is better than two--let us clearly understand that thereby our spiritual nature is sadly maimed1 and therefore that the highest virtue1 which is spiritual beauty and strength1 can not thus be attained4 ,true virtue consists1 not in the extirpation of the lower1 but in its subjection to the higher4 ,the stronger the lower is1 the better1 if only it be held in subjection4 ,for the higher is nourished and strengthened by its connection with the more robust lower1 and the lower is purified1 refined1 and glorified by its connection with the diviner higher1 and by this mutual action the whole plane of being is elevated4 ,it is only by action and reaction of all parts of our complex nature that true virtue is attained4 ,,footnotes3 #a ,the term ,chorology1 used by ,haeckel1 nearly covers the ground4 #b ,ontos-gennao 7individual-making1 or genesis of the individual74 #c ,taxis1 nomos 7relating to science of arrangement74 #d ,this statement is general2 it will be modified hereafter4 #e ,phule-gennao 7kind-making72 genesis of the race4 #f ,this formulation of the laws of organic succession was given by me in #ahfj1 before ,i knew anything of either ,darwin's or ,spencer's evolution4 ,they were my own mode of formulating ,agassiz's views4 #g ,genesis without previous life--spontaneous generation4 #h ,fishes were first introduced in the later ,silurian2 but became dominant in the ,devonian4 #i ,amphibians were introduced in the ,carboniferous1 but true reptile not until the ,permian4 #aj ,of course ,i mean downward in social function4 ,individually the scavenger may be nobler than the statesman4 #aa ,cope1 8,science10 vol4 ii1 p4 #bgd1 #ahhc4 #ab ,boston ,society of ,natural ,history--anniversary memoir1 #ahhj4 ,also1 8,american ,naturalist10 ,june1 #ahhb4 #ac 8,archives des ,sciences10 vol4 liv1 #ahge4 #ad 8,nature10 vol4 xxxi1 p4 #d1 #ahhd4 #ae ,see abstract of ,dr4 ,romanes's views1 8,nature10 vol4 xxxiv1 pp4 #cad1 #ccf1 #cfb4 ,also1 discussions of the same by ,meldola1 ,galton1 ,wallace1 etc41 in immediately subsequent numbers4 #af ,this subject is more fully treated in chapter ,,ix1 p4 #bdj et seq4 #ag ,see an article entitled 8,genesis of ,sex10 8,popular ,science ,monthly10 #ahgi1 vol4 xvi1 p4 #afg4 #ah ,mr4 ,wallace has recently1 in his work on 8,darwinism10 taken strong ground against this ,darwinian factor4 ,he thinks1 for example1 that sexual vigor is the cause of both the splendor of color and the pertinacity which secures the female4 ,we see little difference in this way of putting it4 ,our object1 however1 is not to argue the question of what are true factors1 but simply to give the most accepted1 and1 as it seems to us1 also the most probable view4 #ai ,by reason ,i mean the faculty of dealing with the phenomena of the inner world of consciousness and ideas4 ,animals live in one world--the outer world of sense2 man in two--the outer world of sense1 like animals1 but also in an inner and higher world of ideas4 ,all that is characteristic of man comes of this capacity of dealing with the inner world4 ,in default of a better word ,i call it reason4 ,if any one can suggest a better word1 ,i will gladly adopt it4 #bj ,while all comparative anatomists agree that the lung is a diverticulum from the sophagus1 like the air-bladder of the gar-fish1 some think that it is a different diverticulum1 which is seen first in the dipnoi4 #ba ,undoubtedly the true principle on which primary groups ought to be made is1 identity of general plan of structure1 or traceableness of homology throughout4 ,for these groups are the great primary branches of the tree of life1 and classification ought to represent degrees of genetic relationship4 ,this was ,agassiz's principle1 although he did not admit the genetic relation4 ,this principle has been1 it seems to us1 too much neglected by later systematists4 #bb ,the ,amphioxus1 the lowest of all vertebrates--if vertebrate it may be called--is an exception to #b and #c4 ,in this animal the vertebrate type is not yet fully declared4 #bc ,this is only one example under a general law which it may be well to stop a moment to illustrate4 ,a repetition of similar parts performing the same function is always an evidence of low organization1 and as we rise in the scale of organization such parts usually become fewer and more efficient4 ,thus1 to give one example1 myriapods1 as their name indicates1 have hundreds of locomotive organs--lower crustaceans perhaps thirty or forty4 ,as we go up1 they are reduced to fourteen 7tetradecapods71 then to ten 7decapods71 then in spiders to eight1 in insects to six1 in vertebrates to four1 and in man to two4 ,a similar reduction in number1 but increase in efficiency1 is found in toes1 when they are used for support and locomotion only4 ,in man we find the normal number of five 7#a71 because his hands are used for grasping and the functions of the fingers are not the same2 and 7#b71 because man's development was almost wholly brainward4 ,in other respects his structure is far less specialized than most other mammals4 ,he can not compete with carnivores in strength and ferocity1 nor with herbivores in fleetness4 ,in the struggle for life1 therefore1 there was nothing left for him but increase in intelligence4 ,probably four is the smallest number of locomotive organs consistent with highest efficiency4 ,in retaining but two legs for locomotion1 man has lost in locomotive efficiency1 but by the sacrifice he liberates two limbs for higher functions4 #bd 8,proceedings of ,american ,academy of ,arts and ,sciences10 vol4 xiv1 ,may1 #ahgh4 #be ,fol41 8,archives des ,sciences10 vol4 xiv1 p4 #hd1 #ahhe2 8,science10 vol4 vi1 p4 #ib1 #ahhe4 #bf ,of course1 this is a purely imaginary case4 ,the conditions of development of the eggs of higher animals forbid continuous watching the process4 ,yet we do observe in different individuals all these stages in mammals as well as other animals4 #bg ,these baleen plates are not modifications of teeth1 as might at first be supposed1 but rather of the transverse gum-ridges found on the roof of the mouth of many mammals1 and conspicuous in the horse4 #bh 8,proceedings of the ,california ,academy of ,science10 vol4 v1 p4 #aeb4 #ahgc4 #bi ,for fuller discussion of this subject1 see 8,bulletin of the ,california ,academy of ,science10 ,no4 #h1 #ahhg1 and 8,american ,journal of ,science10 for ,dec41 #ahhg4 #cj 8,origin of ,races of the ,dog40 8,annals and ,magazine of ,natural ,history10 vol4 xvii1 p4 #bie4 #ahhf4 #ca ,mr4 ,galton 78,nature10 ,august #bf1 #ahhf7 has used a diagram similar to the above 7which ,i first used in #ahgi7 to illustrate the law of sexual attraction and repugnance4 #cb ,this subject is more fully discussed by the author in an article entitled 8,genesis of ,sex10 in 8,the ,popular ,science ,monthly10 vol4 xvi1 p4 #afg1 #ahgi4 #cc ,for examples of this the reader is referred to ,cope1 8,bulletin of the ,national ,museum10 ,no4 #a2 and to ,coues's 8,key to ,north ,american ,birds10 last edition4 #cd 8,monatsbericht d4 k4 ,preuss4 ,akademie d4 ,wissenschaft zu ,berlin10 for ,july1 #ahff4 #ce 8,genesis of ,tertiary ,species of ,planorbis at ,steinheim40 ,a4 ,hyatt1 ,anniversary ,memoir of the ,boston ,society of ,natural ,history1 #ahhj4 #cf ,in a letter to the author1 dated ,february #ac1 #ahhg1 ,prof4 ,cope says3 8,such transitions of species are clearly indicated in the ,oreodontid1 where such different forms as ,o4 gracilis and ,o4 ,culbertsoni are connected by intergradations40 #cg 8,american ,naturalist10 #ahgc2 8,popular ,science ,monthly10 ,june1 #ahgc4 #ch ,for a fuller development of this subject the reader is referred to an article by the author1 entitled 8,critical ,periods in the ,history of1 and their ,relation to1 ,evolution0 78,american ,journal of ,science10 vol4 xiv1 p4 #ii1 #ahgg74 #ci 8,reflex ,action and ,theism10 ,william ,james1 8,unitarian ,review0 for ,november1 #ahha4 #dj ,see an article by the author on this subject1 8,american ,journal of ,science10 series ii1 vol4 xxviii1 p4 #cje1 #ahei1 and in 8,popular ,science ,monthly10 vol4 iv1 p4 #aef1 #ahgc4 #da ,all chemical compounds are dissociated by sufficient heat4 #db ,the origin of vital from chemical force in the green leaves of plants can not be doubted2 but this does not1 of course1 explain the mystery of the first origin of life on the earth1 for one condition of the change now is the contact of living matter4 #dc ,i know it is the fashion to ridicule the use of the terms vitality1 vital force1 as a remnant of an old superstition2 and yet the same men who do so use the terms gravity1 electricity1 chemical force1 etc4 ,vital force is indeed correlated with other forces of ,nature1 but is none the less a distinct form of force1 far more distinct than any other unless it be the still higher form of psychical1 and therefore it better deserves a distinct name than any lower form4 ,each form of force gives rise to a peculiar group of phenomena1 and the study of these to a special department of science4 ,now1 the group of phenomena called vital is more peculiar1 more different from other groups than these are from each other1 and the science of physiology is a more distinct department than either physics or chemistry1 and therefore the form of force1 which determines these phenomena1 is more distinct and better entitled to a name than any physical or chemical force4 #dd 8,princeton ,review0 for ,may1 #ahhd4 #de 8,popular ,science ,monthly10 ,december1 #ahgc4 #df ,for a fuller statement of this antithesis1 see an article by the author entitled 8,evolution in ,relation to ,materialism10 8,princeton ,review10 for ,march1 #ahha4 #dg ,johnstone ,stoney1 8,nature10 vol4 xxxi1 p4 #dbb4 #dh 8,nature10 vol4 xxxiv1 p4 #che4 #ahhf4 #di ,so1 again1 see a book recently published 78,nature10 vol4 xliii1 p4 #dfj1 #ahia71 entitled 8,whence comes ,man1 from ,nature or from ,god80 ,the answer is plain4 ,from both--from ,god through ,nature4 ,evolution is the method of creation4 ,,index ,acceleration1 law of1 #agh4 ,african fauna explained1 #bjd4 ,agassiz1 his greatest result1 #bi1 #dc2 relation to evolution1 #cb1 #cg1 #dc2 relation to ,darwin1 #df2 compared with ,kepler1 #dg4 ,ages of geological history1 #af4 ,alpine species explained1 #bae4 ,amphibians1 development of1 #aej4 ,analogy and homology1 #ii4 ,anima of animals1 #cac1 #cag4 ,animal architecture1 styles of1 #bji4 ,animal kingdom1 primary divisions of1 #ajg4 ,animals1 relation of man to1 #caa2 spirit embryonic in1 #caa4 ,antiquity of man1 religion and1 #bhb2 of the earth1 religion and1 #bha4 ,aortic arches1 proofs of evolution from1 #aea4 ,arthropods1 #acb4 ,artificial production of varieties1 #bbb4 ,australia1 fauna and flora of1 explained1 #bjj2 when isolated1 #bjb4 ,barriers limit faunal and floral regions1 #ahh4 ,beauty1 origin of1 #bfi4 ,birds' tails1 changes of1 #agd4 ,brain1 vertebrate1 proofs of evolution from1 #afb2 vertebrate1 changes of1 in phylogenic series1 #afh2 relation to mind1 #cbg1 #cch4 ,brain-physiology as a basis for materialism1 #cjf4 ,branching tree illustrates evolution1 #ac-ae1 #ah1 #aaj1 #bej4 ,brooks1 ,w4 ,k41 on the cause of variations1 #bfb4 ,californian coast-islands1 fauna and flora of1 #baa4 ,causation1 idea of1 from within1 #cdb4 ,cause1 first and second1 #ced4 ,cells1 somatic and germ1 #ic4 ,centers of creation1 specific1 #aid4 ,cephalization1 #aga4 ,chambers1 his views on evolution1 #cd4 ,changes slow at present1 #bff4 ,christ1 the1 #cei2 relation of evolution to1 #cei2 as an agent in human progress1 #cfc4 ,close-breeding1 effects of1 #bcf1 #bdc4 ,coast-islands of ,california1 fauna and flora of1 #baa4 ,comparison1 method of1 #da4 ,conflict between religion and science1 #bhj4 ,continental faunas and floras1 #ahh4 ,continental island life1 #bjh4 ,continuity1 law of1 #ec2 law of1 applied to inorganic forms1 #ed2 to organic forms1 #ef4 ,cope's law of acceleration1 #agh4 ,creation1 special1 #cj1 #fi2 specific centers of1 #aid2 changes in our notions of1 #cdh2 question of mode1 #ceh4 ,cross-breeding1 law of1 #bcf4 ,cross-fertility of artificial varieties1 #bcb4 ,cross-sterility1 #gg1 #bcd4 ,cyclical movement1 law of1 #af1 #bb4 ,darwin1 relation to ,agassiz1 #df2 compared with ,newton1 #dh2 factors of evolution discovered by1 #gd2 objections to his theory of evolution1 #gf4 ,derivation1 origin of inorganic forms by1 #ed2 origin of organic forms by1 #ef4 ,design1 idea of1 from within1 #cde2 argument from1 not destroyed by evolution1 #cdf2 changes in our ideas of1 #cdh2 in ,nature1 question of1 #ceg4 ,differentiation1 law of1 #aa1 #ai2 law of1 in embryonic development1 #ai2 law of1 illustrated1 #add2 of the animal kingdom illustrated1 #agf4 ,disease1 necessity of1 #cfg4 ,divine energy1 forms of1 #cah4 ,divisions of the animal kingdom1 #aag4 ,dogmatism1 theological and scientific1 #bic4 ,domestication1 changes produced by1 #bbb4 ,egg1 development of1 #c1 #ai4 ,egyptian species unchanged in three thousand years1 #bfe4 ,embryology1 proofs of evolution from1 #adh4 ,environment1 physical1 #gc4 ,evil1 problem of1 relation of evolution to1 #cfe2 physical1 necessity of1 #cff2 a condition of progress1 #cff1 #cgc2 organic1 necessity of1 #cfg2 moral1 necessity of1 #cfi4 ,evolution1 what is1 #c1 #h2 scope of1 #c2 type of1 #c1 #h2 examples of1 #e2 popularly limited to the organic kingdom1 #g2 progressive change in1 #i2 laws of1 #aa2 illustrated by branching tree1 #ac-ae1 #ah1 #ij1 #bej2 misconception of1 #ad2 produced by resident forces1 #bg2 germs of the idea1 #cb2 relation of ,agassiz to1 #cb1 #cg1 #dc2 ,lamarck's views on1 #cc2 ,chambers's views on1 #cd2 obstacle to1 removed1 #ce2 confliction with religion imaginary1 #de2 how related to gravitation1 #di2 general evidences of1 #ec2 artificial1 #fj2 observed1 #fb2 certainty of1 #fe2 special proofs of1 #fg2 factors of1 #gc1 #ha2 human contrasted with organic1 #hh2 monotypal and polytypal1 #he2 proofs of1 from the vertebrate skeleton1 #aaa2 from the articulate skeleton1 #acb2 from embryology1 #adh2 from development of amphibians1 #aej2 from aortic arches1 #aea2 from vertebrate brain1 #afb2 from rudimentary organs1 #agi2 from geographical distribution of organisms1 #ahc2 explains geographical diversity1 #aie2 objection to this view1 #bag2 answer1 #bai2 proofs of1 from artificial modifications1 #bbb2 factors of1 operative in domestication1 #bbh2 paroxysmal1 #beg2 material1 nearly completed1 #bfg2 thoroughly established1 #bge2 relation to religion1 #bgf1 #bhb2 relation to materialism1 #bhd2 necessitates great change in religious thought1 #bie2 of forces1 #cae2 relation to revelation1 #cca2 pantheistic objection answered1 #cce2 relation to problem of evil1 #cfe4 ,experimental method largely fails on plane of life1 #dj4 ,factors of evolution1 #gc2 their grades and order of introduction1 #ha2 ,lamarckian1 #ha2 selection1 #hb-he2 ,darwinian1 #hc2 rational1 #hf4 ,faculties1 evolution of1 #bc4 ,faunas and floras1 geographical1 #ahc2 continental1 #ahh2 marine1 #aib2 special cases of distinct1 #aib2 of ,australia1 #bjj2 of ,africa1 #bjd2 of ,madagascar1 #bje2 of continental islands1 #bjh2 of the coast-islands of ,california1 #baa2 of oceanic islands1 #bac2 of lofty mountains1 #bae4 ,fish-tails1 changes of1 in development1 #agb2 in evolution1 #agd4 ,fishes1 age of1 #ag4 ,floras and faunas1 geographical1 #ahc4 ,force1 vital1 correlation of1 #cf2 planes of1 #cad2 evolution of1 #cae2 idea of1 from within1 #cdb4 ,forces1 resident1 evolution by1 #bg2 of ,nature are forms of ,divine energy1 #cag2 different planes of1 #cad4 ,fore-limbs1 vertebrate1 homologies of1 #aac4 ,generation1 spontaneous1 #ae4 ,geographical faunas and floras1 #ahc2 diversity1 theory of1 #aic2 diversity explained by evolution1 #aie2 present diversity determined by ,glacial epoch1 #aih2 objection to this view1 #bag2 answer1 #bai4 ,geological record1 imperfection of1 #beb4 ,glacial epoch determined distribution of species1 #aie1 #aih1 #bae2 changes during1 in ,america1 #aih2 in ,europe1 #aii4 ,god1 relation of1 to ,nature1 #big2 immanence of1 in ,nature1 #cjj2 relation of1 to man1 #cbf2 personality of1 #ccb2 necessary belief in1 #cdd2 different forms of conception1 #cea4 ,good and the true1 relation of1 #bgg4 ,grasshopper1 external anatomy of1 #adc4 ,gravitation1 relation of1 to evolution1 #di2 and religion1 #bha4 ,gyroscope1 #bhh4 ,heliocentric theory and religion1 #bhj4 ,hind-limbs1 vertebrate1 homologies of1 #aba4 ,horse1 genesis of1 #abf4 ,homologies of vertebrate skeleton1 #aaa2 of vertebrate fore-limbs1 #aac2 of vertebrate hind-limbs1 #aba2 of articulate skeleton1 #acb4 ,homology and analogy1 #ii2 only within primary divisions1 #ajh4 ,hyatt1 ,a41 on ,planorbis1 #bed4 ,ideal1 relative and absolute1 #cfd4 ,idealism1 true and false1 #cja4 ,immortality in accord with law1 #caf4 ,individuality1 organic1 #cbe2 spiritual1 #cbe4 ,innocence and virtue compared1 #cgb4 ,inorganic forms1 law of continuity applied to1 #ed4 ,intermediate forms between artificial varieties1 #bcb4 ,islands1 continental and oceanic1 #bjg4 ,kepler compared with ,agassiz1 #dg4 ,lamarck1 evolutionary views of1 #cc1 #gd4 ,law of differentiation1 #aa1 #ai2 of progress of the whole1 #ac1 #bb2 of cyclical movement1 #af1 #bb2 of continuity1 #ec2 of continuity applied to inorganic forms1 #ed2 to organic forms1 #ef2 of differentiation illustrated1 #add2 of acceleration1 #agh2 of cross-breeding1 #bah1 #bcf4 ,laws of evolution1 #aa1 #ai4 ,lepidosiren1 #aja4 ,life1 nature of1 #ce2 imperfectly subject to experiment1 #dj2 relation of1 to philosophy1 #bgg4 ,limbs1 vertebrate1 homology of1 #aac4 ,links1 connecting1 #ab1 #eg1 #ade2 connecting1 elimination of1 #bdh2 connecting1 usually absent from geological faunas1 #bea4 ,liquidambar1 #bah1 #bbj4 ,lobster1 external anatomy of1 #acf4 ,lungs1 formation of1 #ajj4 ,madagascan fauna explained1 #bje4 ,mammals1 age of1 #ag4 ,man1 age of1 #ah2 relation of1 to ,nature1 #cjd2 relation of1 to animals1 #caa2 spirit of1 in relation to the forces of ,nature1 #cac1 #caf2 relation of ,god to1 #cca4 ,marsupials1 #bja4 ,materialism1 relation of1 to evolution1 #bhd2 basis for1 in brain-physiology1 #cjf2 basis for1 in evolution1 #caa4 ,methods1 scientific1 #ch4 ,migration favors diversification1 #gg4 ,mind1 relation of1 to brain1 #cbg1 #cch2 versus mechanics in ,nature1 #cdj4 ,miracles1 question of1 #cef4 ,mollusks1 age of1 #af4 ,monotremes1 #bja4 ,mystery1 changes in our sense of1 #cdg4 ,nature1 relation of ,god to1 #big2 immanence of ,god in1 #cjj2 relation of man to1 #cjd2 has no meaning without spirit1 #cbi2 mind versus mechanics in1 #cdj4 ,natural and supernatural1 #cee4 ,neo-,darwinism1 #ic2 relation of1 to human progress1 #ig4 ,newton compared with ,darwin1 #dh4 ,nominalism and realism reconciled1 #cbi4 ,obstacle to evolution removed1 #ce4 ,oceanic island life1 #bac4 ,ontogenic series1 #i1 #dj4 ,organic forms1 views of origin of1 #bi1 #fh1 #gb1 #bib2 law of continuity applied to1 #ef4 ,organs1 incipient1 #bgj4 ,origin of varieties unexplained1 #bgj4 ,pantheism1 true and false1 #cjb1 #cce4 ,paroxysmal evolution1 #beg4 ,personality behind ,nature1 #cch4 ,personality of ,god1 #ccg1 #cda4 ,philosophy and life1 relations of1 #bgg4 ,phylogenic series1 #aj1 #da4 ,planorbis of ,steinheim1 #bed4 ,primal animals1 #ade4 ,progress of the whole1 law of1 #ac1 #bb4 ,progressive change in evolution1 #i4 ,providence1 question of general and special1 #cee4 ,ranges of organic forms1 #ahf4 ,realism and nominalism reconciled1 #cbi4 ,record1 geological1 imperfection of1 #beb4 ,religion1 so-called conflict of1 with evolution1 #de1 #bhj4 ,religious thought to be reconstructed1 #bie4 ,reproduction1 methods of1 #bcg4 ,reptiles1 age of1 #ag4 ,revelation1 relation of evolution to1 #cca2 not inconsistent with the laws of ,nature1 #ccb2 nature of1 #ccc4 ,reversion of artificial forms1 #bbi4 ,romanes1 ,g4 ,j41 his idea of physiological selection1 #gf1 #hd2 the idea applied1 #bde4 ,rudimentary organs1 proofs of evolution from1 #agi2 organs in man1 #aha4 ,selection1 sexual1 #gd1 #he2 natural1 #gd1 #gi1 #hc2 physiological1 #ge1 #gi1 #hd2 natural1 compared with artificial1 #bbe2 physiological1 applied1 #bde4 ,self-consciousness the sign of spirit-individuality1 #cbe4 ,sequoia1 #bai1 #bbj4 ,sexes1 characters of1 compared1 #bfb4 ,shrimp1 external anatomy of1 #acd4 ,sin a condition of moral evolution1 #cej4 ,skeleton1 vertebrate1 homologies of1 #aaa2 articulate1 homologies of1 #acb2 articulate1 general structure of1 #acd4 ,society1 progress of1 #be4 ,space and time the two fundamental conditions of material existence1 #dh4 ,species1 natural1 more permanent than artificial varieties1 #bbi2 more distinct1 #bcb2 cross-sterile1 #bcb4 ,spirit embryonic in animals1 #caa2 of man related to anima of animals1 #cac2 to forces of ,nature1 #cac1 #caf2 origin of illustrated1 #cbj-cbb2 ,plato's view1 #cbf2 orthodox view1 #cbf2 no meaning in ,nature without1 #cbi4 ,steinheim1 ,planorbis of1 #bed4 ,supernatural and the natural1 #cee4 ,taxonomic series1 #i1 #dj4 ,temperature-regions1 #ahd4 ,tread1 plantigrade and digitigrade1 #abc4 ,true and the good1 relation of1 #bgg4 ,truth tested by effect on life1 #bgg2 not compromise1 #bia4 ,types1 generalized1 #ac4 ,use and disuse of organs1 #gc4 ,useless structures1 how produced1 #gf4 ,variation depends on sexual reproduction1 #bch2 caused by unfavorable conditions1 #bfd4 ,varieties1 artificial production of1 #bbb1 #bce2 artificial production of1 illustrated1 #bbd2 natural and artificial1 compared1 #bbh2 origin of1 unexplained1 #bgj4 8,vestiges of ,creation10 #cd4 ,virtue and innocence compared1 #cgb4 ,vital principle1 #cbh4 ,voluntary social progress1 #bf4 ,weismann's views1 #ic4 ,whales1 rudimentary organs of1 #ahj4 ,,the ,,end4 ,transcribers' ,notes3 ,punctuation1 hyphenation1 and spelling were made consistent when a predominant preference was found in this book2 otherwise they were not changed4 ,simple typographical errors were corrected2 occasional unbalanced quotation marks retained4 ,ambiguous hyphens at the ends of lines were retained4 ,subscripts in chemical formulas are represented here as simple numbers1 such as ,h#b,o and ,,nh#c4 ,illustrations were printed mid-paragraph but have been moved between paragraphs1 usually near to text that references them4 ,footnotes have been collected and repositioned just before the ,index4 ,some in-line paragraph headings are in boldface and some are in italics2 this emphasis has been retained4 ,index not checked for proper alphabetization or correct page references1 but a reference to page #bgd was a typographical error and has been changed to #agd4 ,page #aee3 ,text refers to c c in ,figs4 #ch-ci1 but neither figure appears to contain a c label4