material from the ,google ,print project47 ,,nature ,,series ,,are ,,the ,,effects ,,of ,,use ,,and ,,disuse ,,inherited8 ,,an ,,examination ,,of ,,the ,,view ,,held ,,by ,,spencer ,,and ,,darwin ,,by ,,william ,,platt ,,ball ,,london ,,macmillan ,,and ,,co4 ,,and ,,new ,,york #ahij ,the ,right of ,translation and ,reproduction is ,reserved ,,richard ,,clay ,,and ,,sons1 ,,limited1 ,,london ,,and ,,bungay4 ,,preface4 ,my warmest thanks are due to ,mr4 ,francis ,darwin1 to ,mr4 ,e4 ,b4 ,poulton 7whose interest in the subject here discussed is shown by his share in the translation of ,weismann's ,essays on ,heredity71 and to ,professor ,romanes1 for the help afforded by their kindly suggestions and criticisms1 and for the advice and recommendation under which this essay is now published4 ,encouragement from ,mr4 ,francis ,darwin is to me the more precious1 and the more worthy of grateful recognition1 from the fact that my general conclusion that acquired characters are not inherited is at variance with the opinion of his revered father1 who aided his great theory by the retention of some remains of ,lamarck's doctrine of the inherited effect of habit4 ,i feel as if the son1 as representative of his great progenitor1 were carrying out the idea of an appreciative editor who writes to me3 ,we must say that if ,darwin were still alive1 he would find your arguments of great weight1 and undoubtedly would give to them the serious consideration which they deserve4 ,i hope1 then1 that ,i may be acquitted of undue presumption in opposing a view sanctioned by the author of the ,origin of ,species1 but already stoutly questioned and firmly rejected by such followers of his as ,weismann1 ,wallace1 ,poulton1 ,ray ,lankester1 and others1 to say nothing of its practical rejection by so great an authority on heredity as ,francis ,galton4 ,the sociological importance of the subject has already been insisted on in emphatic terms by ,mr4 ,herbert ,spencer1 and this importance may be even greater than he imagined4 ,civilization largely sets aside the harsh but ultimately salutary action of the great law of ,natural ,selection without providing an efficient substitute for preventing degeneracy4 ,the substitute on which moralists and legislators rely--if they think on the matter at all--is the cumulative inheritance of the beneficial effects of education1 training1 habits1 institutions1 and so forth--the inheritance1 in short1 of acquired characters1 or of the effects of use and disuse4 ,if this substitute is but a broken reed1 then the deeper thinkers who gradually teach the teachers of the people1 and ultimately even influence the legislators and moralists1 must found their systems of morality and their criticisms of social and political laws and institutions and customs and ideas on the basis of the ,darwinian law rather than on that of ,lamarck4 ,looking forward to the hope that the human race may become consciously and increasingly master of itself and of its destiny1 and recognizing the ,darwinian principle of the selection of the fittest as the only means of preventing the moral and physical degeneracy which1 like an internal dry rot1 has hitherto been the besetting danger of all civilizations1 ,i desire that the thinkers who mould the opinions of mankind shall not be led astray from the true path of enduring progress and happiness by reliance on fallacious beliefs which will not bear examination4 ,such1 at least1 is the feeling or motive which has prompted me to devote much time and thought to a difficult but important inquiry in a debatable region of inference and conjecture1 where 7,i am afraid7 evidence on either side can never be absolutely conclusive1 and where1 especially1 the absolute demonstration of a universal negative cannot reasonably be expected4 ,,contents4 ,,page ,,preface v ,,importance ,,and ,,bearing ,,of ,,the ,,inquiry #a ,,spencer',s ,,examples ,,and ,,arguments #f-dd ,,diminution ,,of ,,the ,,jaws #f ,,diminished ,,biting ,,muscles ,,of ,,lap-,,dogs #ab ,,crowded ,,teeth #ad ,,blind ,,cave-,,crabs #ag ,,no ,,concomitant ,,variation ,,from ,,concomitant ,,disuse #ag ,,the ,,giraffe1 ,,and ,,necessity ,,for ,,concomitant ,,variation #ah ,,alleged ,,ruinous ,,effects ,,of ,,natural ,,selection #bc ,,adverse ,,case ,,of ,,neuter ,,insects #bd ,,aesthetic ,,faculties #bi ,,lack ,,of ,,evidence #cd ,,inherited ,,epilepsy ,,in ,,guinea-,,pigs #ce ,,inherited ,,insanity ,,and ,,nervous ,,disorders #cf ,,individual ,,and ,,transmissible ,,type ,,not ,,modified ,,alike #dj ,,darwin',s ,,examples #de-ajj ,,reduced ,,wings ,,of ,,birds ,,of ,,oceanic ,,islands #di ,,drooping ,,ears ,,and ,,deteriorated ,,instincts #ec ,,wings ,,and ,,legs ,,of ,,ducks ,,and ,,fowls #ee ,,pigeons' ,,wings #fb ,,shortened ,,breast-,,bone ,,in ,,pigeons #fd ,,shortened ,,feet ,,in ,,pigeons #gj ,,shortened ,,legs ,,of ,,rabbits #gj ,,blind ,,cave-,,animals #gb ,,inherited ,,habits #gc ,,tameness ,,of ,,rabbits #gf ,,modifications ,,obviously ,,attributable ,,to ,,selection #hb ,,similar ,,effects ,,of ,,natural ,,selection ,,and ,,use-,,inheritance #hc ,,inferiority ,,of ,,senses ,,in ,,europeans #he ,,short-,,sight ,,in ,,watchmakers ,,and ,,engravers #he ,,larger ,,hands ,,of ,,labourers' ,,infants #hg ,,thickened ,,sole ,,in ,,infants #hh ,a ,,source ,,of ,,mental ,,confusion #ia ,,weakness ,,of ,,use-,,inheritance #id ,,inherited ,,injuries #aja-aah ,,inherited ,,mutilations #aja ,,the ,,motmot',s ,,tail #aaj ,,other ,,inherited ,,injuries ,,mentioned ,,by ,,darwin #aaa ,,quasi-,,inheritance #aaf ,,miscellaneous ,,considerations #aai-adc ,,true ,,relation ,,of ,,parents ,,and ,,offspring #aai ,,inverse ,,inheritance #abc ,,early ,,origin ,,of ,,the ,,ova #abd ,,marked ,,effects ,,of ,,use ,,and ,,disuse ,,on ,,the ,,individual #abf ,,would ,,natural ,,selection ,,favour ,,use-,,inheritance8 #abg ,,use-,,inheritance ,,an ,,evil #abh ,,varied ,,effects ,,of ,,use ,,and ,,disuse #acd ,,use-,,inheritance ,,implies ,,pangenesis #acg ,,pangenesis ,,improbable #ach ,,spencer',s ,,explanation ,,of ,,use-,,inheritance #ada ,,conclusions #add-aef ,,use-,,inheritance ,,discredited ,,as ,,unnecessary1 ,,unproven1 ,,and ,,improbable #add ,,modern ,,reliance ,,on ,,use-,,inheritance ,,misplaced #ade ,,are ,,the ,,effects ,,of ,,use ,,and ,,disuse ,,inherited8 ,,importance ,,and ,,bearing ,,of ,,the ,,inquiry4 ,the question whether the effects of use and disuse are inherited1 or1 in other words1 whether acquired characters are hereditary1 is of considerable interest to the general student of evolution2 but it is1 or should be1 a matter of far deeper interest to the thoughtful philanthropist who desires to ensure the permanent welfare and happiness of the human race4 ,so profoundly important1 in fact1 are the moral1 social1 and political conclusions that depend on the answer to this inquiry1 that1 as ,mr4 ,herbert ,spencer rightly says1 it demands1 beyond all other questions whatsoever1 the attention of scientific men4 ,it is obvious that we can produce important changes in the individual4 ,we can1 for example1 improve his muscles by athletics1 and his brain by education4 ,the use of organs enlarges and strengthens them2 the disuse of parts or faculties weakens them4 ,and so great is the power of habit that it is proverbially spoken of as second nature4 ,it is thus certain that we can modify the individual4 ,we can strengthen 7or weaken7 his body2 we can improve 7or deteriorate7 his intellect1 his habits1 his morals4 ,but there remains the still more important question which we are about to consider4 ,will such modifications be inherited by the offspring of the modified individual8 ,does individual improvement transmit itself to descendants independently of personal teaching and example8 ,have artificially produced changes of structure or habit any inherent tendency to become congenitally transmissible and to be converted in time into fixed traits of constitution or character8 ,can the philanthropist rely on such a tendency as a hopeful factor in the evolution of mankind8--the only sound and stable basis of a higher and happier state of things being1 as he knows or ought to know1 the innate and constitutionally-fixed improvement of the race as a whole4 ,if acquired modifications are impressed on the offspring and on the race1 the systematic moral training of individuals will in time produce a constitutionally moral race1 and we may hope to improve mankind even in defiance of the unnatural selection by which a spurious but highly popular philanthropy would systematically favour the survival of the unfittest and the rapid multiplication of the worst4 ,but if acquired modifications do not tend to be transmitted1 if the use or disuse of organs or faculties does not similarly affect posterity by inheritance1 then it is evident that no innate improvement in the race can take place without the aid of natural or artificial selection4 ,herbert ,spencer maintains that the effects of use and disuse are inherited in kind1 and in his ,factors of ,organic ,evolution#a he has supported his contention with a selection of facts and reasonings which ,i shall have the temerity to examine and criticize4 ,darwin also held the same view1 though not so strongly4 ,and here1 to prevent misunderstanding1 ,i may say that the admiration and reverence and gratitude due to ,darwin ought not to be allowed to interfere in the slightest degree with the freest criticism of his conclusions4 ,to perfect his work by the correction of really extraneous errors is as much a sacred duty as to study and apply the great truths he has taught4 ,,footnotes3 #a ,which originally appeared in the ,nineteenth ,century for ,april and ,may1 #ahhf4 ,,spencer',s ,,examples ,,and ,,arguments4 ,,diminution ,,of ,,the ,,jaws ,,in ,,civilized ,,races4 ,mr4 ,spencer verified this by comparing ,english jaws with ,australian and ,negro jaws at the ,college of ,surgeons4#b ,he maintains that the diminution of the jaw in civilized races can only have been brought about by inheritance of the effects of lessened use4 ,but if ,english jaws are lighter and thinner than those of ,australians and ,negroes1 so too is the rest of the skull4 ,as the diminution in the weight and thickness of the walls of the cranium cannot well be ascribed to disuse1 it must be attributed to some other cause2 and this cause may have affected the jaw also4 ,cessation of the process by which natural selection#c favoured strong thick bones during ages of brutal violence might bring about a change in this direction4 ,lightness of structure1 facilitating agility and being economical of material1 would also be favoured by natural selection so far as strength was not too seriously diminished4 ,sexual selection powerfully affects the human face1 and so must affect the jaws--as is shown by the differences between male and female jaws1 and by the relative lightness and smallness of the latter1 especially in the higher races4 ,human preference1 both sexual and social1 would tend to eliminate huge jaws and ferocious teeth when these were no longer needed as weapons of war or organs of prehension1 c4 ,we can hardly assume that the lower half of the face is specially exempt from the influence of natural and sexual selection2 and the effects of these undoubted factors of evolution must be fully considered before we are entitled to call in the aid of a factor whose existence is questioned4 ,after allowing for lost teeth and the consequent alveolar absorption1 and for a reduction proportional to that shown in the rest of the skull1 the difference in average weight in fifty ,european and fourteen ,australian male jaws at the ,college of ,surgeons turned out to be less than a fifth of an ounce1 or about #e per cent4 ,this slight reduction may be much more than accounted for by such causes as disuse in the individual1 human preference setting back the teeth1 and partial transference of the much more marked diminution seen in female jaws4 ,there is apparently no room for accumulated inherited effects of ancestral disuse4 ,the number of jaws is small1 indeed2 but weighing them is at least more decisive than ,mr4 ,spencer's mere inspection4 ,the differences between ,anglo-,saxon male jaws and ,australian and ,tasmanian jaws are most easily explained as effects of human preference and natural selection4 ,we can hardly suppose that disuse would maintain or develop the projecting chin1 increase its perpendicular height till the jaw is deepest and strongest at its extremity1 evolve a side flange1 and enlarge the upper jaw-bone to form part of a more prominent nose1 while drawing back the savagely obtrusive teeth and lips to a more pleasing and subdued position of retirement and of humanized beauty4 ,if human preference and natural selection caused some of these differences1 why are they incompetent to effect changes in the direction of a diminution of the jaw or teeth8 ,and if use and disuse are the sole modifying agents in the case of the human jaw1 why should men have any more chin than a gorilla or a dog8 ,the excessive weight of the ,west ,african jaws at the ,college of ,surgeons is partly against ,mr4 ,spencer's contention1 unless he assumes that ,guinea ,negroes use their jaws far more than the ,australians1 a supposition which seems extremely improbable4 ,the heavier skull and narrower molar teeth point however to other factors than increased use4 ,the striking variability of the human jaw is strongly opposed to the idea of its being under the direct and dominant control of so uniform a cause as ancestral use and disuse4 ,mr4 ,spencer regards a variation of #a oz4 as a large one1 but ,i found that the ,english jaws in the ,college of ,surgeons varied from #a4i oz4 to #d4c oz4 7or #e oz4 if lost teeth were allowed for72 ,australian jaws varied from #b oz4 to #d4e oz4 7with no lost teeth to allow for72 while in ,negro jaws the maximum rose to over #e-a_/b oz4#d ,in spite of disuse some ,european jaws were twice as heavy as the lightest ,australian jaw1 either absolutely or 7in some cases7 relatively to the cranium4 ,the uniformity of change relied upon by ,mr4 ,spencer is scarcely borne out by the facts so far as male jaws are concerned4 ,the great reduction in the weight of female jaws and skulls evidently points to sexual selection and to panmixia under male protection4 ,i think1 on the whole1 we must conclude that the human jaws do not afford satisfactory proof of the inheritance of the effects of use and disuse1 inasmuch as the differences in their weight and shape and size can be more reasonably and consistently accounted for as the result of less disputable causes4 ,,diminished ,,biting ,,muscles ,,of ,,lap-,,dogs4 ,the next example1 the reduced biting muscles1 c41 of lap-dogs is also unsatisfactory as a proof of the inheritance of the effects of disuse2 for the change can readily be accounted for without the introduction of such a factor4 ,the previous natural selection of strong jaws and teeth and muscles is reversed4 ,the conscious or unconscious selection of lap-dogs with the least tendency to bite would easily bring about a general enfeeblement of the whole biting apparatus--weakness of the parts concerned favouring harmlessness4 ,mr4 ,spencer maintains that the dwindling of the parts concerned in clenching the jaw is certainly not due to artificial selection because the modifications offer no appreciable external signs4 ,surely hard biting is sufficiently appreciable by the person bitten without any visual admeasurement of the masseter muscles or the zygomatic arches4 ,disuse during lifetime would also cause some amount of degeneracy2 and ,i am not sure that ,mr4 ,spencer is right in entirely excluding economy of nutrition from the problem4 ,breeders would not over-feed these dogs2 and the puppies that grew most rapidly would usually be favoured4 ,,crowded ,,teeth4 ,the too closely-packed teeth in the decreasing jaws of modern men 7p4 #ac7e are also suggestive of other causes than use and disuse4 ,why is there not simultaneous variation in teeth and jaws1 if disuse is the governing factor8 ,are we to suppose that the size of the human teeth is maintained by use at the same time that the jaws are being diminished by disuse8 ,mr4 ,spencer acknowledges that the crowding of bull-dogs' and lap-dogs' teeth is caused by the artificial selection of shortened jaws4 ,if a similar change is really occurring in man1 could it not be similarly explained by some factor1 such as sexual selection1 which might affect the outward appearance at the cost of less obvious defects or inconveniences8 ,mr4 ,spencer points to the decay of modern teeth as a sign or result of their being overcrowded through the diminution of the jaw by disuse4#f ,but the teeth which are the most frequently overcrowded are the lower incisors4 ,the upper incisors are less overcrowded1 being commonly pressed outwards by the lower arc of teeth fitting inside them in biting4 ,the lower incisors are correspondingly pressed inwards and closer together4 ,yet the upper incisors decay--or at least are extracted--about twenty times as frequently as the closely packed lower incisors4#g ,surely this must indicate that the cause of decay is not overcrowding4 ,the lateness and irregularity of the wisdom teeth are sometimes supposed to indicate their gradual disappearance through want of room in a diminishing jaw4 ,but a note on ,tasmanian skulls in the ,catalogue of the ,college of ,surgeons 7p4 #aii7 shows that this lateness and irregularity have been common among ,tasmanians as well as among civilized races1 so that the change can hardly be attributed to the effects of disuse under civilization4 ,,blind ,,cave-,,crabs4 ,the cave-crabs which have lost their disused eyes but not the disused eye-stalks appear to illustrate the effects of natural selection rather than of disuse4 ,the loss of the exposed1 sensitive1 and worse-than-useless eye1 would be a decided gain1 while the disused eye-stalk1 being no particular detriment to the crab1 would be but slightly affected by natural selection1 though open to the cumulative effects of disuse4 ,the disused but better protected eyes of the blind cave-rat are still of large size 7,origin of ,species1 p4 #aaj74 ,,no ,,concomitant ,,variation ,,from ,,concomitant ,,disuse4 ,it is but fair to add that these instances of the cave-crab's eye-stalk and the closely-packed teeth are put forward by ,mr4 ,spencer with the more immediate object of proving that there is no concomitant variation in co-operative parts1 even when formed out of the same tissue1 like the crab's eye and its peduncle 7pp4 #ab-ad1 #bc1 #cc74 ,it escapes his notice1 however1 that in two out of his three cases it is disuse1 or diminished use1 which fails to cause concomitant variation or proportionate variation4 ,,the ,,giraffe1 ,,and ,,necessity ,,for ,,concomitant ,,variation4 ,having unwittingly shown that lessened use of closely-connected and co-operative parts does not cause concomitant variation in these parts1 ,mr4 ,spencer concludes that the concomitant variation requisite for evolution can only be caused by altered degrees of use or disuse4 ,he elaborately argues that the many co-ordinated modifications of parts necessitated by each important alteration in an animal are so complex that they cannot possibly be brought about except by the inherited effect of the use and disuse of the various parts concerned4 ,he holds1 for instance1 that natural selection is inadequate to effect the numerous concomitant changes necessitated by such developments as that of the long neck of the giraffe4 ,darwin1 however1 on the contrary1 holds that natural selection alone would have sufficed for the production of this remarkable quadruped4#h ,he is surprised at ,mr4 ,spencer's view that natural selection can do so little in modifying the higher animals4 ,thus one of the chief arguments with which ,mr4 ,spencer supports his theory is so poorly founded as to be rejected by a far greater authority on such subjects4 ,all that is needed is that natural selection should preserve the tallest giraffes through times of famine by their being able to reach otherwise inaccessible stores of foliage4 ,the continual variability of all parts of the higher animals gives scope for innumerable changes1 and ,nature is not in a hurry4 ,mr4 ,spencer1 however1 says that the chances against any adequate readjustments fortuitously arising must be infinity to one4 ,but he has also shown that altered degree of use does not cause the needed concomitant variation of co-operative parts4 ,so the chances against a beneficial change in an animal must be1 at a liberal estimate1 infinity to two4 ,mr4 ,spencer1 if he has proved anything1 has proved that it is practically impossible that the giraffe can have acquired a long neck1 or the elk its huge horns1 or that any species has ever acquired any important modification4 ,mr4 ,wallace1 in his ,darwinism1 answers ,mr4 ,spencer by a collection of facts showing that variation is the rule1 that the range of variation in wild animals and plants is much greater than was supposed1 and that each part varies to a considerable extent independently of other parts1 so that the materials constantly ready for natural selection to act upon are abundant in quantity and very varied in kind4 ,while co-operative parts would often be more or less correlated1 so that they would tend to vary together1 coincident variation is not necessary4 ,the lengthened wing might be gained in one generation1 and the strengthened muscle at a subsequent period2 the bird in the meanwhile drawing upon its surplus energy1 aided 7as ,i would suggest7 by the strengthening effect of increased use in the individual4 ,seeing that artificial selection of complicated variations has modified animals in many points either simultaneously or by slow steps1 as with otter-sheep1 fancy pigeons1 c4 7many of the characters thus obtained being clearly independent of use and disuse71 natural selection must be credited with similar powers1 and ,mr4 ,wallace concludes that ,mr4 ,spencer's insuperable difficulty is wholly imaginary4 ,the extract concerning a somewhat similar class of difficulties1 which ,mr4 ,spencer quotes from his ,principles of ,biology1 is faulty in its reasoning1#i though legitimate in its conclusion concerning the increasing difficulty of evolution in proportion with the increasing number and complexity of faculties to be evolved4 ,but this increasing difficulty of complex evolution is only overcome by some favourably-varying individuals and species--not by all4 ,and as the difficulty increases we find neglect and decay of the less-needed faculties--as with domesticated animals and civilized men1 who lose in one direction while they gain in another4 ,the increasing difficulty of complex evolution by natural selection is no proof whatever of use-inheritance#aj except to those who confound difficulty with impossibility4 ,,alleged ,,ruinous ,,effects ,,of ,,natural ,,selection4 ,mr4 ,spencer further contends that natural selection1 by unduly developing specially advantageous modifications without the necessary but complex secondary modifications1 would render the constitution of a variety unworkable 7p4 #bc74 ,but this seems hardly feasible1 seeing that natural selection must continually favour the most workable constitutions1 and will only preserve organisms in proportion as they combine general workableness with the special modification4 ,on the other hand1 according to ,mr4 ,spencer himself1 use-inheritance must often disturb the balance of the constitution4 ,thus it tends to make the jaws and teeth unworkable through the overcrowding and decay of the teeth--there being1 as his illustrations show1 no simultaneous or concomitant or proportional variation in relation to altered degree of use or disuse4 ,,adverse ,,case ,,of ,,neuter ,,insects4 ,mr4 ,spencer also holds that most mental phenomena1 especially where complex or social or moral1 can only be explained as arising from use-inheritance1 which becomes more and more important as a factor of evolution as we advance from the vegetable world and the lower grades of animal life to the more complex activities1 tastes1 and habits of the higher organizations 7preface1 and p4 #gd74 ,but there happens to be a tolerably clear proof that such changes as the evolution of complicated structures and habits and social instincts can take place independently of use-inheritance4 ,the wonderful instincts of the working bees have apparently been evolved 7at least in all their later social complications and developments7 without the aid of use-inheritance--nay1 in spite of its utmost opposition4 ,working bees1 being infertile neuters1 cannot as a rule transmit their own modifications and habits4 ,they are descended from countless generations of queen bees and drones1 whose habits have been widely different from those of the workers1 and whose structures are dissimilar in various respects4 ,in many species of ants there are two1 and in the leaf-cutting ants of ,brazil there are three1 kinds of neuters which differ from each other and from their male and female ancestors to an almost incredible degree4#aa ,the soldier caste is distinguished from the workers by enormously large heads1 very powerful mandibles1 and extraordinarily different instincts4 ,in the driver ant of ,west ,africa one kind of neuter is three times the size of the other1 and has jaws nearly five times as long4 ,in another case the workers of one caste alone carry a wonderful sort of shield on their heads4 ,one of the three neuter classes in the leaf-cutting ants has a single eye in the midst of its forehead4 ,in certain ,mexican and ,australian ants some of the neuters have huge spherical abdomens1 which serve as living reservoirs of honey for the use of the community4 ,in the equally wonderful case of the termites1 or so-called white ants 7which belong1 however1 to an entirely different order of insect from the ants and bees7 the neuters are blind and wingless1 and are divided into soldiers and workers1 each class possessing the requisite instincts and structures adapting it for its tasks4 ,seeing that natural selection can form and maintain the various structures and the exceedingly complicated instincts of ants and bees and wasps and termites in direct defiance of the alleged tendency to use-inheritance1 surely we may believe that natural selection1 unopposed by use-inheritance1 is equally competent for the work of complex or social or mental evolution in the many cases where the strong presumptive evidence cannot be rendered almost indisputable by the exceptional exclusion of the modified animal from the work of reproduction4 ,ants and bees seem to be capable of altering their habits and methods of action much as men do4 ,bees taken to ,australia cease to store honey after a few years' experience of the mild winters4 ,whole communities of bees sometimes take to theft1 and live by plundering hives1 first killing the queen to create dismay among the workers4 ,slave ants attend devotedly to their captors1 and fight against their own species4 ,forel reared an artificial ant-colony made up of five different and more or less hostile species4 ,why cannot a much more intelligent animal modify his habits far more rapidly and comprehensively without the aid of a factor which is clearly unnecessary in the case of the more intelligent of the social insects8 ,,aesthetic ,,faculties4 ,the modern development of music and harmony 7p4 #ai7 is undeniable1 but why could it only have been brought about by the help of the inheritance of the effects of use8 ,why are we to suppose that minor traits such as the aesthetic perceptions cannot have been evolved by natural selection 7p4 #bj7 or by sexual selection8 ,darwin holds that our musical faculties were developed by sexual preference long before the acquisition of speech4 ,he believes that the rhythms and cadences of oratory are derived from previously developed musical powers--a conclusion exactly opposite to that arrived at by ,mr4 ,spencer4#ab ,the emotional susceptibility to music1 and the delicate perceptions needed for the higher branches of art1 were apparently the work of natural and sexual selection in the long past4 ,civilization1 with its leisure and wealth and accumulated knowledge1 perfects human faculties by artificial cultivation1 develops and combines means of enjoyment1 and discovers unsuspected sources of interest and pleasure4 ,the sense of harmony1 modern as it seems to be1 must have been a latent and indirect consequence of the development of the sense of hearing and of melody4 ,use1 at least1 could never have called it into existence4 ,nature favours and develops enjoyments to a certain extent1 for they subserve self-preservation and sexual and social preference in innumerable ways4 ,but modern aesthetic advance seems to be almost entirely due to the culture of latent abilities1 the formation of complex associations1 the selection and encouragement of talent1 and the wide diffusion and imitation of the accumulated products of the well-cultivated genius of favourably varying individuals4 ,the fact that uneducated persons do not enjoy the higher tastes1 and the rapidity with which such tastes are acquired or professed1 ought to be sufficient proof that modern culture is brought about by far swifter and more potent influences than use-inheritance4 ,neither would this hypothetical factor of evolution materially aid in explaining the many other rapid changes of habit brought about by education1 custom1 and the changed conditions of civilization generally4 ,powerful tastes--as is incontestably shown in the cases of alcohol and tobacco--lie latent for ages1 and suddenly become manifest when suitable conditions arise4 ,every discovery1 and each step in social and moral evolution1 produces its wide-spreading train of consequences4 ,i see no reason why use-inheritance need be credited with any share in the cumulative results of the invention of printing and the steam-engine and gunpowder1 or of freedom and security under representative government1 or of science and art and the partial emancipation of the mind of man from superstition1 or of the innumerable other improvements or changes that take place under modern civilization4 ,mr4 ,spencer suggests an inquiry whether the greater powers possessed by eminent musicians were not mainly due to the inherited effect of the musical practice of their fathers 7p4 #ai74 ,but these great musicians inherited far more than their parents possessed4 ,the excess of their powers beyond their parents' must surely be attributed to spontaneous variation2 and who shall say that the rest was in any way due to use-inheritance8 ,if1 too1 the superiority of geniuses proves use-inheritance1 why should not the inferiority of the sons of geniuses prove the existence of a tendency which is the exact opposite of use-inheritance8 ,but nobody collects facts concerning the degenerate branches of musical families4 ,only the favourably varying branches are noticed1 and a general impression of rapid evolution of talent is thus produced4 ,such cases might be explained1 too1 by the facts that musical faculty is strong in both sexes1 that musical families associate together1 and that the more gifted members may intermarry4 ,great musicians are often astonishingly precocious4 ,meyerbeer played brilliantly at the age of six4 ,mozart played beautifully at four4 ,are we to suppose that the effect of the adult practice of parents was inherited at this early age8 ,if use-inheritance was not necessary in the case of ,handel1 whose father was a surgeon1 why is it needed to account for ,bach8 ,,lack ,,of ,,evidence4 ,the direct proofs of use-inheritance are not as plentiful as might be desired1 it appears 7pp4 #bd-bh74 ,this acknowledged lack of recognized evidence is indeed the weakest feature in the case1 though ,mr4 ,spencer would fain attribute this lack of direct proof to insufficient investigation and to the inconspicuous nature of the inheritance of the modification4 ,but there is an almost endless abundance of conspicuous examples of the effects of use and disuse in the individual4 ,how is it that the subsequent inheritance of these effects has not been more satisfactorily observed and investigated8 ,horse-breeders and others could profit by such a tendency1 and one cannot help suspecting that the reason they ignore it must be its practical inefficacy1 arising probably from its weakness1 its obscurity and uncertainty or its non-existence4 ,,inherited ,,epilepsy ,,in ,,guinea-,,pigs4 ,brown-,sequard's discovery that an epileptic tendency artificially produced by mutilating the nervous system of a guinea-pig is occasionally inherited may be a fact of considerable weight1 or on the other hand it may be entirely irrelevant4 ,cases of this kind strike one as peculiar exceptions rather than as examples of a general rule or law4 ,they seem to show that certain morbid conditions may occasionally affect both the individual and the reproductive elements or transmissible type in a similar manner2 but then we also know that such prompt and complete transmission of an artificial modification is widely different from the usual rule4 ,exceptional cases require exceptional explanations1 and are scarcely good examples of the effect of a general tendency which in almost all other cases is so inconspicuous in its immediate effects4 ,further remarks on this inherited epilepsy can be most conveniently introduced later on in connection with ,darwin's explanation of the inherited mutilation which it usually accompanies1 but which ,mr4 ,spencer does not mention4 ,,inherited ,,insanity ,,and ,,nervous ,,disorders4 ,mr4 ,spencer infers that1 because insanity is usually hereditary1 and insanity can be artificially produced by various excesses1 therefore this artificially-produced insanity must also be hereditary 7p4 #bh74 ,direct evidence of this conclusion would be better than a mere inference which may beg the very question at issue4 ,that the liability to insanity commonly runs in families is no proof that strictly non-inherited insanity will subsequently become hereditary4 ,i think that theories should be based on facts rather than facts on theories1 especially when those facts are to be the basis or proof of a further theory4 ,mr4 ,spencer also points out that he finds among physicians the belief that nervous disorders of a less severe kind are inheritable--a general belief which does not necessarily include the transmission of purely artificially-produced disorders1 and so misses the point which is really at issue4 ,he proceeds1 however1 to state more definitely that men who have prostrated their nervous systems by prolonged overwork or in some other way1 have children more or less prone to nervousness4 ,the following observations will1 ,i think1 warrant at least a suspension of judgment concerning this particular form of use-inheritance4 7#a7 ,the nervousness is seen in the children at an early age1 although the nervous prostration from which it is supposed to be derived obviously occurs in the parent at a much later period of life4 ,this change in time is contrary to the rule of inheritance at corresponding periods2 and1 together with the unusual promptness and comparative completeness of the inheritance1 it may indicate a special injury or deterioration of the reproductive elements rather than true inheritance4 ,the healthy brain of early life has failed to transmit its robust condition4 ,is use-inheritance1 then1 only effective for evil8 ,does it only transfer the newly-acquired weakness1 and not the previous long-continued vigour8 7#b7 ,members of nervous families would be liable to suffer from nervous prostration1 and by the ordinary law of heredity alone would transmit nervousness to their children4 7#c7 ,the shattered nerves or insanity resulting from alcoholic and other excesses1 or from overwork or trouble1 are evidently signs of a grave constitutional injury which may react upon the reproductive elements nourished and developed in that ruined constitution4 ,the deterioration in parent and child may often display itself in the same organs--those probably which are hereditarily weakest4 ,acquired diseases or disorders thus appear to be transmitted1 when all that was conveyed to the offspring was the exciting cause of a lowered vitality or disordered action1 together with the ancestral liability to such diseases under such conditions4 7#d7 ,francis ,galton says that it is hard to find evidence of the power of the personal structure to react upon the sexual elements1 that is not open to serious objection4 ,some of the cases of apparent inheritance he regards as coincidence of effect4 ,thus the fact that a drunkard will often have imbecile children1 although his offspring previous to his taking to drink were healthy1 is an instance of simultaneous action1 and not of true inheritance4 ,the alcohol pervades his tissues1 and1 of course1 affects the germinal matter in the sexual elements as much as it does that in his own structural cells1 which have led to an alteration in the quality of his own nerves4 ,exactly the same must occur in the case of many constitutional diseases that have been acquired by long-continued irregular habits4#ac ,,individual ,,and ,,transmissible ,,type ,,not ,,modified ,,alike ,,by ,,the ,,direct ,,effect ,,of ,,changed ,,habits ,,or ,,conditions4 ,mr4 ,spencer finds it hard to believe that the modifications conveyed to offspring are not identical in tendency with the changes effected in the parent by altered use or habit 7pp4 #bc-be1 #cd74 ,but it is perfectly certain that the two sets of effects do not necessarily correspond4 ,the effect of changed habits or conditions on the individual is often very far from coinciding with the effects on the reproductive elements or the transmissible type4 ,the reproductive system is extremely sensitive to very slight changes1 and is often powerfully affected by circumstances which otherwise have little effect on the individual 7,origin of ,species1 p4 #g74 ,various animals and plants become sterile when domesticated or supplied with too much nourishment4 ,the native ,tasmanians have already become extinct from sterility caused by greatly changed diet and habits4 ,if1 as ,mr4 ,spencer teaches1 continued culture and brain-work will in time produce lessened fertility or comparative sterility1 we may yet have to be careful that intellectual development does not become a species of suicide1 and that the culture of the race does not mean its extinction--or at least the extinction of those most susceptible of culture4 ,the reproductive elements are also disturbed and modified in innumerable minor ways4 ,changed conditions or habits tend to produce a general plasticity of type1 the indefinite variability thus caused being apparently irrelevant to the change1 if any1 in the individual4#ad ,a vast number of variations of structure have certainly arisen independently of similar parental modification as the preliminary4 ,whatever first caused these spontaneous congenital variations affected the reproductive elements quite differently from the individual4 ,when a new peculiarity first appears we can never predict whether it will be inherited4 ,many varieties of plants only keep true from shoots1 and not from seed1 which is by no means acted on in the same way as the individual plant4 ,seeing that such plants have two reproductive types1 both constant1 it is evident that these cannot both be modified in the same way as the parent is modified4 ,many parental modifications of structure and habit are certainly not conveyed to neuter ants and bees2 other modifications1 which are not seen in the parents1 being conveyed instead4 ,many other circumstances tend to show that the individual and the transmissible type are independent of each other so far as modifications of parts are concerned4 ,it may seem natural to expect the transmission of an enlarged muscle or a cultivated brain1 but1 on the other hand1 why should it be unreasonable to expect that a modification which was non-congenital in origin should still remain non-congenital8 ,why should the non-transmission of that which was not transmitted be surprising8 ,mr4 ,spencer thinks that the non-transmission of acquired modifications is incongruous with the great fact of atavism4 ,but the great law of the inheritance of that which is a development of the transmissible type does not necessarily imply the inheritance of modifications acquired by the individual4 ,because ,english children may inherit blue eyes and flaxen hair from their ,anglo-,saxon ancestors1 it by no means follows that an ,englishman must inherit his father's sunburnt complexion or smooth-shaven face4 ,of course atavism ultimately adopts many instances of revolt against its sway4 ,but to assume that these changes of type follow the personal change rather than cause it1 is to assume the whole question at issue4 ,that like begets like is true as a broad principle1 but it has many exceptions1 and the non-heredity of acquired characters may be one of them4 ,,footnotes3 #b ,principles of ,biology1 ,sec4 #aff1 footnote4 ,the ,english jaws are somewhat lighter than the ,australian jaws1 though ,i could not undertake to affirm that they are really shorter and smaller4 ,in the typical skulls depicted on p4 #fh of the official guide to the mammalian galleries at ,south ,kensington1 the typical ,caucasian jaw is very much larger than the ,tasmanian jaw1 although the repulsively obtrusive teeth of the latter convey the contrary idea to the imagination4 ,mr4 ,spencer's assumption that the ancient ,britons had large jaws appears to me erroneous4 7,see ,professor ,rolleston's ,scientific ,papers and ,addresses1 i4 p4 #bej47 #c ,romanes1 ,galton1 and ,weismann have made great use of this principle in explaining the diminution of disused organs4 ,weismann has given it the name of ,panmixia1--all individuals being equally free to survive and commingle their variations1 and not merely selected or favoured individuals4 ,see his ,essays on ,heredity1 c41 p4 #ij 7,clarendon ,press74 #d ,inclusive in each case of fixed strengthening wire weighing about a sixteenth of an ounce or less4 #e ,references of course are to ,factors of ,organic ,evolution4 #f ,p4 #ac2 and ,nineteenth ,century1 ,february1 #ahhh1 p4 #baa4 #g ,tomes's ,dental ,surgery1 pp4 #bgc-bge4 ,tomes observes that it is as yet uncertain in what way civilization predisposes to caries4 ,but he shows that caries is caused by the lime salts in the teeth being attacked by acids from decomposing food in crevices1 from artificial drink such as cyder1 from sugar1 from medicine1 and from vitiated secretions of the mouth4 ,it is evident that in civilized races natural selection cannot so rigorously insist on sound teeth1 sound constitutions1 and protective alkaline saliva4 ,the reaction of the civilized mouth is often acid1 especially when the system is disordered by dyspepsia or other diseases or forms of ill-health common under civilization4 ,the main supply of saliva1 which is poured from the cheeks opposite the upper molars1 is often acid when in small quantities4 ,but the submaxillary and sub-lingual saliva poured out at the foot of the lower incisors and held in the front part of the jaw as in a spoon1 differs from parotid saliva in being more alkaline 7,foster's ,text ,book of ,physiology1 p4 #bch2 ,tomes1 pp4 #bhd1 #fhe74 ,one observer says that the reaction near the lower incisors is never acid4 ,hence 7,i conclude7 the remarkable immunity of the lower incisors and canines from decay1 an immunity which extends backwards in a lessening degree to the first and second bicuspids4 ,the close packing of the lower incisors may assist by preventing the retention of decaying fragments of food4 ,sexual selection may promote caries by favouring white teeth1 which are more prone to decay than yellow ones4 ,acid vitiation of the mucus might account both for caries and 7possibly7 for the strange infertility of some inferior races under civilization4 #h ,origin of ,species1 pp4 #aih-i2 ,variation of ,animals and ,plants under ,domestication1 vol4 ii4 p4 #cbh footnote1 also p4 #bjf4 #i ,mr4 ,spencer weakly argues that an advantageous attribute 7such as swiftness1 keen sight1 courage1 sagacity1 strength1 c47 cannot be increased by natural selection unless it is of greater importance1 for the time being1 than most of the other attributes2 and that natural selection cannot develop any one superiority when animals are equally preserved by other superiorities4 ,but as natural selection will simultaneously eliminate tendencies to slowness1 blindness1 deafness1 stupidity1 c41 it must favour and improve many points simultaneously1 although no one of them may be of greater importance than the rest4 ,of course the more complicated the evolution the slower it will be2 but time is plentiful1 and the amount of elimination is correspondingly vast4 #aj ,i venture to coin this concise term to signify the direct inheritance of the effects of use and disuse in kind4 ,having a name for a thing is highly convenient2 it facilitates clearness and accuracy in reasoning1 and in this particular inquiry it may save some confusion of thought from double or incomplete meanings in the shortened phrases which would otherwise have to be employed to indicate this great but nameless factor of evolution4 #aa ,origin of ,species1 pp4 #bcj-bcb2 ,bates's ,naturalist on the ,amazons4 ,darwin is surprised that no one has hitherto advanced the demonstrative case of neuter insects1 against the well-known doctrine of inherited habit1 as advanced by ,lamarck4 ,as he justly observes1 it proves that with animals1 as with plants1 any amount of modification may be effected by the accumulation of numerous1 slight1 spontaneous variations1 which are in any way profitable1 without exercise or habit having been brought into play4 ,for peculiar habits confined to the workers or sterile females1 however long they might be followed1 could not possibly affect the males and fertile females1 which alone leave any descendants4 ,some slight modification of these remarks1 however1 may possibly be needed to meet the case of factitious queens1 who 7probably through eating particles of the royal food7 become capable of producing a few male eggs4 #ab ,descent of ,man1 pp4 #egc1 #egb1 and footnote4 #ac ,contemporary ,review1 ,december1 #ahge1 p4 #ib4 #ad ,see ,origin of ,species1 pp4 #e-h4 ,changed conditions induce an almost indefinite amount of fluctuating variability1 by which the whole organization is rendered in some degree plastic 7,descent of ,man1 p4 #cj74 ,it also appears that the nature of the conditions is of subordinate importance in comparison with the nature of the organism in determining each particular form of variation2--perhaps of not more importance than the nature of the spark1 by which a mass of combustible matter is ignited1 has in determining the nature of the flames 7,origin of ,species1 p4 #h74 ,,darwin',s ,,examples4 ,the most formidable cases brought forward by ,mr4 ,spencer are from ,darwin4 ,i shall endeavour to show1 however1 that ,darwin was probably wrong in retaining the older explanation of these facts1 and that the remains of the ,lamarckian theory of use-inheritance need not any longer encumber the great explanation which has superseded that fallacious and unproven theory and has rendered it totally unnecessary4 ,meanwhile ,i think it is an excellent sign that ,mr4 ,spencer has to complain that ,nowadays most naturalists are more ,darwinian than ,mr4 ,darwin himself--inasmuch as they are inclined to say that there is no proof that the effects of use and disuse are inherited4 ,other excellent signs are the recent issue of a translation of ,weismann's important essays on this and kindred subjects1#ae the strong support given to his views by ,wallace in his ,darwinism1 and their adoption by ,ray ,lankester in his article on ,zoology in the latest edition of the ,encyclopaedia ,britannica4 ,so sound and cautious an investigator as ,francis ,galton had also in #ahge concluded that acquired modifications are barely1 if at all1 inherited1 in the correct sense of that word4 ,darwin's belief in the inheritance of acquired characters was more or less hereditary in the family4 ,his grandfather1 ,erasmus ,darwin1 anticipated ,lamarck's views in his ,zoonomia1 which ,darwin at one time greatly admired4 ,his father was convinced of the inherited evil effects of alcohol1 and to this extent at least he strongly impressed the belief in the inheritance of acquired characters upon his children's minds4#af ,darwin must also have been imbued with ,lamarckian ideas from other sources1 although ,dr4 ,grant's enthusiastic advocacy entirely failed to convert him to a belief in evolution4#ag ,nevertheless1 he says1 it is probable that the hearing rather early in life such views maintained and praised may have favoured my upholding them under a different form in my ,origin of ,species--a remark which refers to ,lamarck's views on the general doctrine of evolution1 but might also prove equally true if applied to ,darwin's partial retention of the ,lamarckian explanation of that evolution4 ,professor ,huxley has pointed out that in ,darwin's earlier sketch of his theory of evolution 7#ahdd7 he attached more weight to the inheritance of acquired habits than he does in his ,origin of ,species published fifteen years later4#ah ,he appears to have acquired the belief in early life without first questioning and rigorously testing it as he would have done had it originated with himself4 ,in later life it appeared to assist his theory of evolution in minor points1 and in particular it appeared absolutely indispensable to him as the only explanation of the diminution of disused parts in cases where1 as in domestic animals1 economy of growth seemed to be practically powerless4 ,he failed to adequately notice the effect of panmixia1 or the withdrawal of selection1 in causing or allowing degeneracy and dwindling under disuse2 and he hardly attached sufficient importance to the fact that rudimentary organs and other supposed effects of use or disuse are quite as marked features in neuter insects which cannot transmit the effects of use and disuse as they are in the higher animals4 ,,reduced ,,wings ,,of ,,birds ,,of ,,oceanic ,,islands4 ,darwin himself has pointed out that the rudimentary wings of island beetles1 at first thought to be due to disuse1 are mainly brought about by natural selection--the best-winged beetles being most liable to be blown out to sea4 ,but he says that in birds of the oceanic islands not persecuted by any enemies1 the reduction of their wings has probably been caused by disuse4 ,this explanation may be as fallacious as it is acknowledged to have been in the case of the island beetles4 ,according to ,darwin's own views1 natural selection must at least have played an important part in reducing the wings2 for he holds that natural selection is continually trying to economize every part of the organization4 ,he says3 ,if under changed conditions of life a structure1 before useful1 becomes less useful1 its diminution will be favoured1 for it will profit the individual not to have its nutriment wasted in building up an useless structure4444 ,thus1 as ,i believe1 natural selection will tend in the long run to reduce any part of the organization1 as soon as it becomes1 through changed habits1 superfluous4#ai ,if1 as ,darwin powerfully urges 7and he here ignores his usual explanation71 ostriches' wings are insufficient for flight in consequence of the economy enforced by natural selection1#bj why may not the reduced wings of the dodo1 or the penguin1 or the apteryx1 or of the ,cursores generally1 be wholly attributed to natural selection in favour of economy of material and adaptation of parts to changed conditions8 ,the great principle of economy is continually at work shaping organisms1 as sculptors shape statues1 by removing the superfluous parts2 and a mere glance at the forms of animals in general will show that it is well-nigh as dominant and universal a principle as is that of the positive development of useful parts4 ,other causes1 moreover besides actual economy1 would favour shorter and more convenient wings on oceanic islands4 ,in the first place1 birds that were somewhat weak on the wing would be most likely to settle on an island and stay there4 ,shortened wings would then become advantageous because they would restrain fatal migratory tendencies or useless and perilous flights in which the birds that flew furthest would be most often carried away by storms and adverse winds4 ,reduced wings would keep the birds near the shelter and the food afforded by the island and its neighbourhood1 and in some cases would become adapted to act as fins or flappers for swimming under water in pursuit of fish4 ,the reduced size of the wings of these island birds is paralleled by the remarkable thinness1 c41 of the shell of the gigantic land-tortoise of the ,galapagos ,islands4 ,the changes seen in the carapace can hardly have been brought about by the inherited effects of special disuse4 ,why then should not the reduction of equally useless1 more wasteful1 and perhaps positively dangerous wings be also due to an economy which has become advantageous to bird and reptile alike through the absence of the mammalian rivals whose places they are evidently being modified to fill8 ,the complete loss of the wings in neuter ants and termites can scarcely be due to the inherited effects of disuse2 and as natural selection has abolished these wings in spite of the opposition of use-inheritance1 it must clearly be fully competent to reduce wings without its aid4 ,in considering the rudimentary wings of the apteryx1 or of the moa1 emu1 ostrich1 c41 we must not forget the frequent or occasional occurrence of hard seasons1 and times of drought and famine1 when ,nature eliminates redundant1 wasteful1 and ill-adapted organisms in so severe and wholesale a fashion4 ,where enemies are absent there would be unrestrained multiplication1 and this would greatly increase the severity of the competition for food1 and so hasten the elimination of disused and useless parts4 ,,drooping ,,ears ,,and ,,deteriorated ,,instincts4 ,mr4 ,galton has pointed out that existing races and existing organs are only kept at their present high pitch of organic excellence by the stringent and incessant action of natural or artificial selection2 and the simple relaxation or withdrawal of such selective influences will almost necessarily result in a certain amount of deterioration1 independently even of the principle of economy4#ba ,i think that this cessation of a previous selective process will account for the drooping--but not diminished--ears of various domesticated animals 7human preference and increased weight evidently aiding71 and also for the inferior instincts seen in them and in artificially-fed caterpillars of the silk-moth1 which now often commit the strange mistake of devouring the base of the leaf on which they are feeding1 and consequently fall down4 ,anyhow1 ,i fail to see that anything is proved by this latter case1 except that natural instinct may be perverted or aborted under unnatural conditions and a changed method of selection which abolishes the powerful corrective formerly supplied by natural selection4 ,,wings ,,and ,,legs ,,of ,,ducks ,,and ,,fowls4 ,the reduced wings and enlarged legs of domesticated ducks and fowls are attributed by ,darwin and ,spencer to the inheritance of the effects of use and disuse4 ,but the inference by no means follows4 ,natural selection would usually favour these adaptive changes1 and they would also have been aided by an artificial selection which is often unconscious or indirect4 ,birds with diminished power of flight would be less difficult to keep and manage1 and in preserving and multiplying such birds man would be unconsciously bringing about structural changes which would easily be regarded as effects of use and disuse4 ,about eighteen centuries ago ,columella and ,varro speak of the necessity of keeping ducks in netted enclosures like other wild fowl1 so that at this period there was danger of their flying away4#bb ,is it not probable that the best fliers would escape most frequently1 or would pine most if kept confined8 ,on the other hand1 birds with lessened powers of flight would not be eliminated as under natural conditions1 but would be favoured2 and natural selection1 together with artificial selection of the most flourishing birds1 would thicken and strengthen the legs to meet increased demands upon them4 ,the diminution of the duck's wing is not great even in the birds that never fly1 and from this we must deduct the direct effect of disuse on the individual during its lifetime4 ,as ,weismann suggests1 the inherited portion of the change could only be ascertained by comparing the bones1 c41 of wild and tame ducks similarly reared4 ,if individual disuse diminished the weight of the duck's wing-bones by #i per cent4 there would be nothing left to account for4 ,i suspect that investigation would reveal anomalies inconsistent with the theory of use-inheritance4 ,thus according to ,darwin's tables of comparative weights and measurements#bc the leg-bones of the ,penguin duck have slightly diminished in length1 although they have increased #ci per cent4 in weight4 ,relatively to the weight of the skeleton1 the leg-bones have shortened in the tame breeds of ducks by over #e per cent4 7and in two breeds by over #h per cent47 although they have increased more than #bh per cent4 in proportional weight4#bd ,how can increased use simultaneously shorten and thicken these bones8 ,if the relative shortening is attributed to a heavier skeleton1 then the apparently reduced weight of the wing-bones is fully accounted for by the same circumstance1 and disuse has had no inherited effect4 ,another strange circumstance is that the wing-bones have diminished in length only4 ,the shortening is about #f per cent4 more than in the shortened legs1 and it amounts to #aa per cent4 as compared with the weight of the skeleton4 ,such a shortening should represent a reduction of #bi per cent4 in weight1 whereas the actual reduction in the weight of the wing-bones relatively to the weight of the skeleton is only #i per cent4 even in the breeds that never fly4 ,independently of shortening1 the disused wing-bones have actually thickened or increased in weight4 ,in the ,aylesbury duck the disproportion caused by these conflicting changes is so great that the wing-bones are #dg per cent4 heavier than they should be if their weight had varied proportionally with their length4#be ,the reduction in weight on which ,darwin relies seems to be entirely due to the shortening1 and this shortening appears to be irrelevant to disuse1 since the wings of the ,call duck are similarly shortened in their proportions by #ab per cent41 although this bird habitually flies to such an extent that ,darwin partly attributes the greatly increased weight of its wing-bones to increased use under domestication4 ,we find that all the changes are in the direction of shorter and thicker bones--a tendency which must be largely dependent upon the suspension of the rigorous elimination which keeps the bones of the wild duck long and light4 ,the used leg-bones and the disused wing-bones have alike been shortened and thickened1 though in different proportions4 ,natural or artificial selection might easily thicken legs without lengthening them1 or shorten wings without eliminating strong heavy bones1 but it can hardly be contended that use-inheritance has acted in such conflicting ways4 ,the thickening of the wing-bones has actually more than kept pace with any increase of weight in the skeleton1 in spite of the effect of individual disuse and of the alleged cumulative effect of ancestral disuse for hundreds of generations4 ,the case of the duck deserves special attention as a crucial one1 if only from the fact that in this instance1 and in this instance only1 has ,darwin given the weights of the skeletons1 thus furnishing the means for a closer examination of his details than is usually possible4 ,if we ignore such factors as selection1 panmixia1 correlation1 and the effects of use and disuse during lifetime1 and still regard the case of the domestic duck as a valid proof of the inheritance of the effects of use and disuse1 we must also accept it as an equally valid proof that the effects of use and disuse are not inherited4 ,nay1 we may even have to admit that1 in two points out of four1 the inherited effect of use and disuse on successive generations is exactly opposite to the immediate effect on the individual4 ,among fowls the wing-bones have lost much in weight but little or nothing in length--which is the reverse of what has occurred in ducks1 although disuse is alleged to be the common cause in both cases4 ,some of the fowls which fly least have their wing-bones as long as ever4 ,in the case of the ,silk and ,frizzled fowls--ancient breeds which cannot fly at all--and in that of the ,cochins1 which can hardly fly up to a low perch1 ,darwin observes how truly the proportions of an organ may be inherited although not fully exercised during many generations4#bf ,in four out of twelve breeds the wing-bones had become slightly heavier relatively to the leg-bones4 ,do not these facts tend to show that the changes in fowls' wings are due to fluctuating variability and selective influences rather than to a general law whereby the effects of disuse are cumulatively inherited8 ,,pigeons' ,,wings4 ,concerning pigeons' wings ,darwin says3 ,as fancy pigeons are generally confined in aviaries of moderate size1 and as even when not confined they do not search for their own food1 they must during many generations have used their wings incomparably less than the wild rock-pigeon 444 but when we turn to the wings we find what at first appears a wholly different and unexpected result4#bg ,this unexpected increase in the spread of the wings from tip to tip is due to the feathers1 which have lengthened in spite of disuse4 ,excluding the feathers1 the wings were shorter in seventeen instances1 and longer in eight4 ,but as artificial selection has lengthened the wings in some instances1 why may it not have shortened them in others8 ,wings with shortened bones would fold up more neatly than the long wings of the ,carrier pigeon for instance1 and so might unconsciously be favoured by fanciers4 ,the selection of elegant birds with longer necks or bodies would cause a relative reduction in the wings--as with the ,pouter1 where the wings have been greatly lengthened but not so much as the body4#bh ,slender bodies1 too1 and the lessened divergence of the furculum1#bi would slightly diminish the spread of the wings1 and so would affect the measurements taken4 ,as the wing-bones1 moreover1 are to some extent correlated with the beak and the feet1 the artificial selection of shortened beaks might tend to shorten the wing as well as the feet4 ,under these circumstances how can we be sure of the actual efficacy of use-inheritance8 ,surely selection is as fully competent to effect slight changes in the direction of use-inheritance as it undoubtedly is to effect great changes in direct opposition to that alleged factor of evolution4 ,,shortened ,,breast-,,bone ,,in ,,pigeons4 ,the shortening of the sternum in pigeons is attributed to disuse of the flight muscles attached to it4 ,the bone is only shortened by a third of an inch1 but this represents a very remarkable reduction in proportional length1 which ,darwin estimates at from one-seventh to one-eighth1 or over #ac per cent4 ,this marked reduction1 too1 quite unlike the slight reduction of the wing-bones to which the other ends of the muscles are attached1 was universal in the eleven specimens measured by ,darwin2 and the bone1 though acknowledged to have been modified by artificial selection in some breeds1 is not so open to observation as wings or legs4 ,even1 however1 if this relative shortening of the sternum remained otherwise inexplicable1 it might still be as irrelevant to use and disuse as is the fact that many breeds of fancy pigeons have lost a rib1 having only seven where the ancestral rock-pigeon has eight4#cj ,but the excessive reduction in the sternum is far from being inexplicable4 ,in the first place ,darwin has somewhat over-estimated it4 ,instead of comparing the deficiency of length with the increased length which should have been acquired 7since the pigeons have increased in average size7 he compares it with the length of the breast-bone in the rock-pigeon4#ca ,by this method if a pigeon had doubled in dimensions while its breast-bone remained unaltered1 the reduction would be put down as #ajj per cent41 whereas obviously the true reduction would be one-half1 or #ej per cent4 of what the bone should be4 ,avoiding this error and a minor fallacy besides1 a sound estimate reduces the supposed reduction of #ac or #ad per cent4 to one of #aa4g per cent41 which is still of course a considerable diminution4 ,part of this reduction must be due to the direct effect of disuse during the lifetime of the individual4 ,another and perhaps very considerable part of the relative change must be attributed to the lengthening of the neck or body by artificial selection1 or to other modifications of shape and proportion effected directly or indirectly by the same cause4#cb ,the reduction is greatest in the ,pouter 7#ah-a_/b per cent47 and in the ,pied ,scanderoon 7#ag-a_/b per cent474 ,in the former the body has been greatly elongated by artificial selection and three or four additional vertebrae have been acquired in the hinder part of the body4#cc ,in the latter a long neck increases the length of the bird1 and so causes1 or helps to cause1 the relative shortening of the breast-bone4 ,in the ,english ,carrier--which experiences the effects of disuse1 as it is too valuable to be flown--the relative reduction of #aa per cent4 is apparently more than accounted for by the elongated neck4 ,the ,dragon also has a long neck4 ,in the ,pouter1 although the breast-bone has been shortened by #ah-a_/b per cent4 relatively to the length of the body1 it has lengthened by #bj per cent4 relatively to the bulk of the body4#cd ,darwin forgot to ask whether allowance must not be made for a frequent1 or perhaps general1 elongation of the neck and the hinder part of the body1 and the relative shortening or the throwing forward of the central portion containing the ribs 7frequently one less in number7 and the sternum4 ,the whole body of the pigeon is so much under the control of artificial selection1 that every precaution must be taken to guard against such possible sources of error4#ce ,under domestication there would be a suspension of the previous elimination of reduced breast-bones by natural selection 7,weismann's panmixia71 and a diminution of the parts concerned in flying might even be favoured1 as lessened powers of continuous flight would prevent pigeons from straying too far1 and would fit them for domestication or confinement4 ,such causes might reduce some of the less observed parts affected by flying1 while still leaving the wing of full size for occasional flight1 or to suit the requirements of the pigeon-fanciers4 ,a change might thus be commenced like that seen in the rudimentary keel of the sternum in the owl-parrot of ,new ,zealand1 which has lost the power of flight although still retaining fairly-developed wings4 ,,shortened ,,feet ,,in ,,pigeons4 ,darwin thinks it highly probable that the short feet of most breeds of pigeons are due to lessened use1 though he owns that the effects of correlation with the shortened beak are more plainly shown than the effects of disuse4#cf ,but why need the inherited effects of disuse be called in to explain an average reduction of some #e per cent41 when ,darwin's measurements show that in the breeds where long beaks are favoured the principle of correlation between these parts has lengthened the foot by #ac per cent4 in spite of disuse8 ,,shortened ,,legs ,,of ,,rabbits4 ,in the case of the domestic rabbit ,darwin notices that the bones of the legs have 7relatively7 become shorter by an inch and a half4 ,but as the leg-bones have not diminished in relative weight1#cg they must clearly have grown thicker or denser4 ,if disuse has shortened them1 as ,darwin supposes1 why has it also thickened them8 ,the ears and the tail have been lengthened in spite of disuse4 ,why then may not the ungainly hind-legs have been shortened by human preference independently of the inherited effects of disuse8 ,by relying on apparently favourable instances and neglecting the others it would be easy to arrive at all manner of unsound conclusions4 ,we might thus become convinced that vessels tend to sail northwards1 or that a pendulum oscillates more often in one direction than in the other4 ,it must not be forgotten that it would be easy to cite an enormous number of cases which are in direct conflict with the supposed law of use-inheritance4 ,,blind ,,cave-,,animals4 ,weak or defective eyesight is by no means rare as a spontaneous variation in animals1 the great ,french veterinary ,huzard going so far as to say that a blind race of horses could soon be formed4 ,natural selection evolves blind races whenever eyes are useless or disadvantageous1 as with parasites4 ,this may apparently be done independently of the effects of disuse1 for certain neuter ants have eyes which are reduced to a more or less rudimentary condition1 and neuter termites are blind as well as wingless4 ,in one species of ant 7,eciton vastator7 the sockets have disappeared as well as the eyes4 ,in deep caves not only would natural selection cease to maintain good eyesight but it would persistently favour blindness--or the entire removal of the eye when greatly exposed1 as in the cave-crab--and as ,dr4 ,ray ,lankester has indicated1#ch there would have been a previous selection of animals which through spontaneous weakness1 sensitiveness1 or other affection of the eye found refuge and preservation in the cave1 and a subsequent selection of the descendants whose fitness for relative darkness led them deeper into the cave or prevented them from straying back to the light with its various dangers and severer competition4 ,panmixia1 however1 as ,weismann has shown1 would probably be the most important factor in causing blindness4 ,,inherited ,,habits4 ,darwin says3 ,a horse is trained to certain paces1 and the colt inherits similar consensual movements4#ci ,but selection of the constitutional tendency to these paces1 and imitation of the mother by the colt1 may have been the real causes4 ,the evidence1 to be satisfactory1 should show that such influences were excluded4 ,men acquire proficiency in swimming1 waltzing1 walking1 smoking1 languages1 handicrafts1 religious beliefs1 c41 but the children only appear to inherit the innate abilities or constitutional proclivities of their parents4 ,even the songs of birds1 including their call-notes1 are no more inherited than is language by man 7,descent of ,man1 p4 #hf74 ,they are learned from the parent4 ,nestlings which acquire the song of a distinct species1 teach and transmit their new song to their offspring4 ,if use-inheritance has not fixed the song of birds1 why should we suppose that in a single generation it has transmitted a newly-taught method of walking or trotting8 ,it is alleged that dogs inherit the intelligence acquired by association with man1 and that retrievers inherit the effects of their training4#dj ,but selection and imitation are so potent that the additional hypothesis of use-inheritance seems perfectly superfluous4 ,where intelligence is not highly valued and carefully promoted by selection1 the intelligence derivable from association with man does not appear to be inherited4 ,lap-dogs1 for instance1 are often remarkably stupid4 ,darwin also instances the inheritance of dexterity in seal-catching as a case of use-inheritance4#da ,but this is amply explained by the ordinary law of heredity4 ,all that is needed is that the son shall inherit the suitable faculties which the father inherited before him4 ,,tameness ,,of ,,rabbits4 ,darwin holds that in some cases selection alone has modified the instincts and dispositions of domesticated animals1 but that in most cases selection and the inheritance of acquired habits have concurred in effecting the change4 ,on the other hand1 he says1 habit alone in some cases has sufficed2 hardly any animal is more difficult to tame than the young of the wild rabbit2 scarcely any animal is tamer than the young of the tame rabbit2 but ,i can hardly suppose that domestic rabbits have often been selected for tameness alone2 so that we must attribute at least the greater part of the inherited change from extreme wildness to extreme tameness to habit and long-continued close confinement4#db ,but there are strong1 and to me irresistible1 arguments to the contrary4 ,i think that the following considerations will show that the greater part1 if not the whole1 of the change must be attributed to selection rather than to the direct inheritance of acquired habit4 7#a7 ,for a period which may cover thousands of generations1 there has been an entire cessation of the natural selection which maintains the wildness 7or excessive fear1 caution1 activity1 c47 so indispensably essential for preserving defenceless wild rabbits of all ages from the many enemies that prey upon them4 7#b7 ,during this same extensive period of time man has usually killed off the wildest and bred from the tamest and most manageable4 ,to some extent he has done this consciously4 ,it is very conducive to successful breeding to keep only such as are quiet and tractable1 says an authority on rabbits1#dc and he enjoins the selection of the handsomest and best-tempered does to serve as breeders4 ,to a still greater extent man has favoured tameness unconsciously and indirectly4 ,he has systematically selected the largest and most prolific animals1 and has thus doubled the size and the fertility of the domestic rabbit4 ,in consciously selecting the largest and most flourishing individuals and the best and most prolific mothers1 he must have unconsciously selected those rabbits whose relative tameness or placidity of disposition rendered it possible for them to flourish and to produce and rear large and thriving families1 instead of fretting and pining as the wilder captives would do4 ,when we consider how exceedingly delicate and easily disturbed yet all-important a function is that of maternity in the continually breeding rabbit1 we see that the tamest and the least terrified would be the most successful mothers1 and so would continually be selected1 although man cared nothing for the tameness in itself4 ,the tamest mothers would also be less liable to neglect or devour their offspring1 as rabbits commonly do when their young are handled too soon1 or even when merely frightened by mice1 c41 or disturbed by changed surroundings4 7#c7 ,we must remember the extraordinary fecundity of the rabbit and the excessive amount of elimination that consequently takes place either naturally or artificially4 ,where nature preserved only the wildest1 man has preserved the tamest4 ,if there is any truth in the ,darwinian theory1 this thorough and long-continued reversal of the selective process must have had a powerful effect4 ,why should it not be amply sufficient to account for the tameness and mental degeneracy of the rabbit without the aid of a factor which can readily be shown to be far weaker in its normal action than either natural or artificial selection8 ,why may not the tameness of the rabbit be transferred to the group of cases in which ,darwin holds that habit has done nothing1 and selection has done all8 7#d7 ,if use-inheritance has tamed the rabbit1 why are the bucks still so mischievous and unruly8 ,why is the ,angora breed the only one in which the males show no desire to destroy the young8 ,why1 too1 should use-inheritance be so much more powerful in the rabbit than with other animals which are far more easily tamed in the first instance8 ,wild young rabbits when domesticated remain unconquerably wild1 and1 although they may be kept alive1 they pine and rarely come to any good4 ,yet the animal which acquires least tameness--or apparently1 indeed1 none at all--inherits most6 ,it appears1 in fact1 to inherit that which it cannot acquire--a circumstance which indicates the selection of spontaneous variations rather than the inheritance of changed habits4 ,such variations occasionally occur in animals in a marked degree4 ,of a litter of wolf-cubs1 all brought up in the same way1 one became tame and gentle like a dog1 while the others preserved their natural savagery4 ,is it not probable that permanent domestication was rendered possible by the inevitable selection of spontaneous variations in this direction8 ,the excessive tameness1 too1 of the young rabbit1 while easily explicable as a result of unconscious selection1 is not easily explained as a result of acquired habit4 ,no particular care is taken to tame or teach or domesticate rabbits4 ,they are bred for food1 or for profit or appearance1 and they are left to themselves most of their time4 ,as ,sir ,j4 ,sebright notices with some surprise1 the domestic rabbit is not often visited1 and seldom handled1 and yet it is always tame4 ,,modifications ,,obviously ,,attributable ,,to ,,selection4 ,innumerable modifications in accordance with altered use or disuse1 such as the enlarged udders of cows and goats1 and the diminished lungs and livers in highly bred animals that take little exercise1 can be readily and fully explained as depending on selection4 ,as the fittest for the natural or artificial requirements will be favoured1 natural or artificial selection may easily enlarge organs that are increasingly used and economize in those that are less needed4 ,i therefore see no necessity whatever for calling in the aid of use-inheritance as ,darwin does1 to account for enlarged udders1 or diminished lungs1 or the thick arms and thin legs of canoe ,indians1 or the enlarged chests of mountaineers1 or the diminished eyes of moles1 or the lost feet of certain beetles1 or the reduced wings of logger-headed ducks1 or the prehensile tails of monkeys1 or the displaced eyes of soles1 or the altered number of teeth in plaice1 or the increased fertility of domesticated animals1 or the shortened legs and snouts of pigs1 or the shortened intestines of tame rabbits1 or the lengthened intestines of domestic cats1 c4#dd ,changed habits and the requisite change of structure will usually be favoured by natural selection2 for habit1 as ,darwin says1 almost implies that some benefit great or small is thus derived4 ,,similar ,,effects ,,of ,,natural ,,selection ,,and ,,use-,,inheritance4 ,here we perceive a difficulty which will equally trouble those who affirm use-inheritance and those who deny4 ,broadly speaking1 the adaptive effects ascribed to use-inheritance coincide with the effects of natural selection4 ,the individual adaptability 7as shown in the thickening of skin1 fur1 muscle1 c41 under the stimulus of friction1 cold1 use1 c47 is identical in kind and direction with the racial adaptability under natural selection4 ,consequently the alleged inheritance of the advantageous effects of use and disuse cannot readily be distinguished from the similarly beneficial effects of natural selection4 ,the indisputable fact that natural selection imitates or simulates the beneficial effects ascribed to use-inheritance may be the chief source and explanation of a belief which may prove to be thoroughly fallacious4 ,a similar simulation of course occurs under domestication1 where natural selection is partly replaced by artificial selection of the best adapted and therefore most flourishing animals1 while in disused parts panmixia or the comparative cessation of selection will aid or replace economy of growth in causing diminution4#de ,,inferiority ,,of ,,senses ,,in ,,europeans4 ,the inferiority of ,europeans1 in comparison with savages1 in eyesight and in the other senses1 is attributed to the accumulated and transmitted effect of lessened use during many generations4#df ,but why may we not attribute it to the slackened and diverted action of the natural selection which keeps the senses so keen in some savage races8 ,,short-,,sight ,,in ,,watchmakers ,,and ,,engravers4 ,darwin notices that watchmakers and engravers are liable to be short-sighted1 and that short-sight and long-sight certainly tend to be inherited4#dg ,but we must be careful not to beg the question at issue by assuming that the frequent heredity of short sight necessarily covers the heredity of artificially-produced short-sight4 ,elsewhere1 however1 ,darwin states more decisively that there is ground for believing that it may often originate in causes acting on the individual affected1 and may thence-forward become transmissible4#dh ,this impression may arise 7#a7 from the facts of ordinary heredity--the ancestral liability being excited in father and son by similar artificial habits1 such as reading1 and viewing objects closely as among watchmakers and engravers--or by constitutional deterioration from indoor life1 c41 acting upon a constitutional liability of the eye to the something like inflammation of the coats1 under which they yield and so cause shortness of sight by altering the spherical shape of the eye-ball4 7#b7 ,panmixia1 or the suspension of natural selection1 together with altered habits1 will account for an increase of short-sight among the population generally4 7#c7 ,long-sighted people could not work at watchmaking and engraving so comfortably and advantageously as at other occupations1 and hence would be less likely to take to such callings4 ,,larger ,,hands ,,of ,,labourers' ,,infants4#di ,these are best explained as the result of natural selection and of the diminution of the hand by sexual selection in the gentry4 ,if the larger hands of labourers' infants are really due to the inherited effects of ancestral use1 why does the development occur so early in life1 instead of only at a corresponding period1 as is the rule8 ,during the first few years of its life1 at least1 the labourer's infant does no more work than the gentleman's child4 ,why are not the effects of this disuse inherited by the labourer's infant8 ,if the enlargement of the infant's hand illustrates the transference of a character gained later in life1 it is evident that the transference must take place in spite of the inherited effects of disuse4 ,,thickened ,,sole ,,in ,,infants4 ,darwin also attributes the thickened sole in infants1 long before birth1 to the inherited effects of pressure during a long series of generations4#ej ,but disuse should make the infant's sole thin1 and it is this thinness that should be inherited4 ,if we suppose the inheritance of the thickened soles of later life to be transferred to an earlier period1 we have the anomaly of the inherited effects of disuse at that earlier period being overpowered by the untimely inheritance of the effects of use at another4 ,on the other hand1 it is clear that natural selection would favour thickened soles for walking on1 and might also promote an early development which would ensure their being ready in good time for actual use2 for variations in the direction of delay would be cut off1 while variations in the other direction would be preserved4 ,anyhow1 the mere transference of a character to an earlier period is no proof of use-inheritance4 ,the real question is whether the thickened sole was gained by natural selection or by the inherited effects of pressure1 and the mere transference or hastened appearance of the thickening does not in any degree solve this question4 ,it merely excludes the effect of disuse during lifetime1 and thus presents a fallacious appearance of being decisive4 ,the thickened sole of the unborn infant1 however1 like the lanugo or hairy covering1 is probably a result of the direct inheritance of ancestral stages of evolution1 of which the embryo presents a condensed epitome4 ,while the relative thinness of the infant's sole might be pointed to as the effect of disuse during a long series of generations1 its thickness is rather an illustration of atavism still resisting the effects of long-continued disuse4 ,there is nothing to show that the inheritable portion of the full original thickness was not gained by natural selection rather than by the directly inherited effect of use2 and the latter1 being cumulative and indiscriminative in its action1 would apparently have made the sole very much thicker and harder than it is4 ,if natural selection were not supreme in such cases1 how could we account for the effects of pressure resulting in hard hoofs in some cases and only soft pads in others8 ,a ,,source ,,of ,,mental ,,confusion4 ,of course in a certain sense this thickening of the sole has resulted from use4 ,in one sense or other1 most--or perhaps all--of the results of natural selection are inherited effects of use or disuse4 ,natural selection preserves that which is of use and which is used1 while it eliminates that which is useless and is not used4 ,the most confident assertions of the effects of use and disuse in modifying the heritable type1 appear to rest on this indefeasible basis4 ,darwin's statements concerning the effects of use and disuse in evolution can frequently be read in two senses4 ,they often command assent as undeniable truisms as they stand1 but are of course written in another and more debatable sense4 ,thus in the case of the shortened wings and thickened legs of the domestic duck1 ,i believe equally with ,darwin and ,spencer that no one will dispute that they have resulted from the lessened use of the wings and the increased use of the legs4 ,use is at bottom the determining circumstance in evolution generally4 ,the trunk of the elephant1 the fin of the fish1 the wing of the bird1 the cunning hand of man and his complicated brain--and1 in short1 all organs and faculties whatsoever--can only have been moulded and developed by use--by usefulness and by using--but not necessarily by use-inheritance1 not necessarily by directly inherited effects of use or disuse of parts in the individual4 ,so1 too1 reduced or rudimentary organs are due to disuse1 but it by no means follows that the diminution is caused by any direct tendency to the inheritance of the effects of disuse in the individual4 ,the effects of natural selection are commonly expressible as effects of use and disuse1 just as adaptation in nature is expressible in the language of teleology4 ,but use-inheritance is no more proven by one of these necessary coincidences than special design is by the other4 ,the inevitable simulation of use-inheritance may be entirely deceptive4 ,darwin thinks that there can be no doubt that use in our domestic animals has strengthened and enlarged certain parts1 and disuse diminished them2 and that such modifications are inherited4 ,undoubtedly such or similar modifications have often been inherited1 but how can ,darwin possibly tell that they are not due to the simulation of use-inheritance by natural or artificial selection acting upon general variability8 ,of the inevitability of selection and of its generally adaptive tendencies there can be no doubt1 and panmixia would tend to reduce disused parts2 so that there must always remain grave doubts of the alleged inheritance of the similar effects of use and disuse1 unless we can accomplish the extremely difficult feat of excluding both natural and artificial selection as causes of enlargement1 and panmixia and selection as causes of dwindling4 ,,weakness ,,of ,,use-,,inheritance4 ,use-inheritance is normally so weak that it appears to be quite helpless when opposed to any other factor of evolution4 ,natural selection evolves and maintains the instincts of ants and termites in spite of use-inheritance to a more wonderful degree than it evolves the instincts of almost any other animal with the fullest help of use-inheritance4 ,it develops seldom-used horns or natural armour just as readily as constantly-used hoofs or teeth4 ,sexual selection evolves elaborate structures like the peacock's tail in spite of disuse and natural selection combined4 ,artificial selection appears to enlarge or diminish used parts or disused parts with equal facility4 ,the assistance of use-inheritance seems to be as unnecessary as its opposition is ineffective4 ,the alleged inheritance of the effects of use and disuse in our domestic animals must be very slow and slight4#ea ,darwin tells us that there is no good evidence that this ever follows in the course of a single generation4 ,several generations must be subjected to changed habits for any appreciable result4#eb ,what does this mean8 ,one of two things4 ,either the tendency is very weak1 or it is non-existent4 ,if it is so weak that we cannot detect its alleged effects till several generations have elapsed1 during which time the more powerful agency of selection has been at work1 how are we to distinguish the effects of the minor factor from that of the major8 ,are we to conclude that use-inheritance plus selection will modify races1 just as ,voltaire firmly held that incantations1 together with sufficient arsenic1 would destroy flocks of sheep8 ,is it not a significant fact that the alleged instances of use-inheritance so often prove to be self-conflicting in their details8 ,for satisfactory proof of the prevalence of a law of use-inheritance we require normal instances where selection is clearly inadequate to produce the change1 or where it is scarcely allowed time or opportunity to act1 as in the immediate offspring of the modified individual4 ,of the first kind of cases there seems to be a plentiful lack4 ,of the latter kind1 according to ,darwin1 there appears to be none--a circumstance which contrasts strangely and suspiciously with the many decisive cases in which variation from unknown causes has been inherited most strikingly in the immediate offspring4 ,it must be expected1 indeed1 that among these innumerable cases some will accidentally mimic the alleged effects of use-inheritance4 ,if ,darwin had felt certain that the effects of habit or use tended in any marked degree to be conveyed directly and cumulatively to succeeding generations1 he could hardly have given us such cautious1 half-hearted encouragement of good habits as the following3--,it is not improbable that after long practice virtuous tendencies may be inherited4 ,habits1 moreover followed during many generations probably tend to be inherited4#ec ,this is probable1 independently of use-inheritance4 ,the many generations specified or implied1 will allow time for the play of selective as well as of cumulatively-educative influences4 ,there must apparently be a constitutional or inheritable predisposition or fitness for the habits spoken of1 which otherwise would scarcely be continued for many generations1 except by the favourably-varying branches of a family3 which again is selection rather than use-inheritance4 ,where is the necessity for even the remains of the ,lamarckian doctrine of inherited habit8 ,seeing how powerful the general principle of selection has shown itself in cases where use-inheritance could have given no aid or must even have offered its most strenuous opposition1 why should it not equally be able to develop used organs or repress disused organs or faculties without the assistance of a relatively weak ally8 ,selection evolved the remarkable protective coverings of the armadillo1 turtle1 crocodile1 porcupine1 hedgehog1 c42 it formed alike the rose and its thorn1 the nut and its shell2 it developed the peacock's tail and the deer's antlers1 the protective mimicry of various insects and butterflies1 and the wonderful instincts of the white ants2 it gave the serpent its deadly poison and the violet its grateful odour2 it painted the gorgeous plumage of the ,impeyan pheasant and the beautiful colours and decorations of countless birds and insects and flowers4 ,these1 and a thousand other achievements1 it has evidently accomplished without the help of use-inheritance4 ,why should it be thought incapable of reducing a pigeon's wing or enlarging a duck's leg8 ,why should it be credited with the help of an officious ally in effecting comparatively slight changes1 when great and striking modifications are effected without any such aid8 ,,footnotes3 #ae ,weismann's ,essays on ,heredity1 c4 ,clarendon ,press1 #ahhi4 #af ,life and ,letters1 i4 p4 #af4 ,darwin's reverence for his father was boundless and most touching4 ,he would have wished to judge everything else in the world dispassionately1 but anything his father had said was received with almost implicit faith2 444 he hoped none of his sons would ever believe anything because he said it1 unless they were themselves convinced of its truth--a feeling in striking contrast with his own manner of faith 7,life and ,letters1 i4 pp4 #aj1 #aa74 #ag ,ibid41 i4 p4 #ch4 #ah ,life and ,letters1 ii4 p4 #ad4 #ai ,origin of ,species1 pp4 #aag1 #aah4 #bj ,ibid41 p4 #ahj4 #ba ,contemporary ,review1 ,december1 #ahge1 pp4 #hi1 #ic4 #bb ,variation of ,animals and ,plants under ,domestication1 i4 #bib4 #bc ,variation of ,animals and ,plants under ,domestication1 i4 #bii-cja4 #bd ,to keep pace with this lateral increase in weight1 the leg-bones should have lengthened considerably so that their total deficiency in proportional length is #ag per cent41--a changed proportion which being linear is more excessive than the increase of weight by #bh per cent4 ,so marked is the effect of the combined thickening and shortening that in the ,aylesbury breed--which is the most typically representative one--the leg-bones have become #gj per cent4 heavier than they should be if their thickness had continued to be proportional to their length4 #be ,this excessive thickening under disuse appears to be due partly to a positive lateral enlargement or increase of proportional weight of about #g-a_/b per cent41 and partly to a shortening of about #ae per cent4 ,carefully calculated1 the reduction of the weight of the wing-bones in this breed is only #h4c per cent4 relatively to the whole skeleton1 or only #e per cent4 relatively to the skeleton minus legs and wings4 ,the latter method is the more correct1 since the excessive weight of the leg-bones increases the weight of the skeleton more than the diminished weight of the wing-bones reduces it4 #bf ,variation of ,animals and ,plants under ,domestication1 i4 #bhd4 #bg ,variation of ,animals and ,plants under ,domestication1 i4 #ahd1 #ahe4 #bh ,ibid41 i4 #add1 #ade4 #bi ,ibid41 i4 #ahe4 #cj ,variation of ,animals and ,plants under ,domestication1 i4 #age4 #ca ,variation of ,animals and ,plants under ,domestication1 i4 #ahd4 ,i suspect that ,darwin was in poor health when he wrote this page4 ,he nods at least four times in it4 ,twice he speaks of twelve breeds where he obviously should have said eleven4 #cb ,if a prominent breast is admired and selected by fanciers1 the sternum might shorten in assuming a more forward and vertical position4 ,if the shortening of the sternum is entirely due to disuse1 it seems strange that ,darwin has not noticed any similar shortening in the sternum of the duck4 ,but selection has not tended to make the duck elegant1 or pigeon-breasted2 it has enlarged the abdominal sack instead1 besides allowing the addition of an extra rib in various cases4 #cc ,variation of ,animals and ,plants under ,domestication1 #add1 #age4 #cd ,variation of ,animals and ,plants under ,domestication1 i4 #agi4 #ce ,in the six largest breeds the shortening of the sternum is nearly twice as great as in the three smaller breeds which remain nearest the rock-pigeon in size4 ,we can hardly suppose that use-inheritance especially affects the eight breeds that have varied most in size4 ,if we exclude these1 there is only a total shortening of #g per cent4 to be accounted for4 #cf ,variation of ,animals and ,plants under ,domestication1 i4 #ahc1 #ahf4 #cg ,variation of ,animals and ,plants under ,domestication1 i4 #acj1 #ace2 ii4 #bhh4 #ch ,encyclopaedia ,britannica1 article ,zoology4 #ci ,variation of ,animals and ,plants under ,domestication1 ii4 #cfg4 #dj ,variation of ,animals and ,plants under ,domestication1 ii4 #cfg4 ,why then does the cheetah inherit ancestral habits so inadequately that it is useless for the chase unless it has first learned to hunt for itself before being captured8 7ii4 #acc74 #da ,descent of ,man1 p4 #cc4 #db ,origin of ,species1 pp4 #baj1 #baa4 #dc ,e4 ,s4 ,delamer on ,pigeons and ,rabbits1 pp4 #acb1 #ajc4 ,for other points referred to1 see pages #acc1 #ajb1 #ajj1 #ie1 #aca4 #dd ,origin of ,species1 pp4 #ahh1 #aaj2 ,descent of ,man1 pp4 #cb-ce2 ,variation of ,animals and ,plants under ,domestication1 ii4 #bhi1 #bic4 ,use or disuse during lifetime of course co-operates1 and in some cases1 as in that of the canoe ,indians1 may be the principal or even perhaps the sole cause of the change4 #de ,for the importance of panmixia as invalidating ,darwin's strongest evidence for use-inheritance--namely1 that drawn from the effects of disuse in highly-fed domestic animals where there is supposed to be no economy of growth--see ,professor ,romanes on ,panmixia1 ,nature1 ,april #c1 #ahij4 #df ,descent of ,man1 p4 #cc4 #dg ,descent of ,man1 p4 #cc4 #dh ,variation of ,animals and ,plants under ,domestication1 i41 #dec4 #di ,descent of ,man1 p4 #cc4 #ej ,descent of ,man1 p4 #cc4 #ea ,wallace shows that the changes in our domestic animals1 if spread over the thousands of years since the animals were first tamed1 must be extremely insignificant in each generation1 and he concludes that such infinitesimal effects of use and disuse would be swallowed up by the far greater effects of variation and selection 7,darwinism1 p4 #dcf74 ,professor ,romanes has replied to him in the ,contemporary ,review 7,august #ahhi71 showing that this is no disproof of the existence of the minor factor1 inasmuch as slight changes in each generation need not necessarily be matters of life and death to the individual1 although their cumulative development by use-inheritance might eventually become of much service4 ,but selection would favour spontaneous variations of a similarly serviceable character4 ,the slightest tendency to eliminate the extreme variations in either direction would proportionally modify the average in a breed4 ,use-inheritance appears to be so relatively weak a factor that probably neither proof nor disproof of its existence can ever be given1 owing to the practical impossibility of disentangling its effects 7if any7 from the effects of admittedly far more powerful factors which often act in unsuspected ways4 ,thus wild ducklings1 which can easily be reared by themselves1 invariably die off if reared with tame ones 7,variation1 c41 i4 #bib1 ii4 #bai74 ,they cannot get their fair share in the competition for food1 and are completely eliminated4 ,professor ,romanes fully acknowledges that there is the gravest possible doubt as to the transmission of the effects of disuse 7,letter on ,panmixia1 ,nature1 ,march #ac1 #ahij74 #eb ,variation of ,animals and ,plants under ,domestication1 ii4 #bhg-bhi4 #ec ,descent of ,man1 pp4 #fab1 #aca4 ,,inherited ,,injuries4 ,,inherited ,,mutilations4 ,the almost universal non-inheritance of mutilations seems to me a far more valid argument against a general law of modification-inheritance than the few doubtful or abnormal cases of such inheritance can furnish in its favour4 ,no inherited effect has been produced by the docking of horses' tails for many generations1 or by a well-known mutilation which has been practised by the ,hebrew race from time immemorial4 ,as lost or mutilated parts are reproduced in offspring independently of the existence of those parts in the parent1 there is the less reason to suppose that the particular condition of parental parts transmits itself1 or tends to transmit itself1 to the offspring4 ,so unsatisfactory is the argument derivable from inherited mutilations that ,mr4 ,spencer does not mention them at all1 and ,darwin has to attribute them to a special cause which is independent of any general theory of use-inheritance4#ed ,darwin's most striking case--and to my mind the only case of any importance--is that of ,brown-,sequard's epileptic guinea-pigs1 which inherited the mutilated condition of parents who had gnawed off their own gangrenous toes when anaesthetic through the sciatic nerve having been divided4#ee ,darwin also mentions a cow that lost a horn by accident1 followed by suppuration1 and subsequently produced three calves which had on the same side of the head1 instead of a horn1 a bony lump attached merely to the skin4 ,such cases may seem to prove that mutilation associated with morbid action is occasionally inherited or repeated with a promptitude and thoroughness that contrast most strikingly with the imperceptible nature of the immediate inheritance of the effects of use and disuse2 but they by no means prove that mutilation in general is inheritable1 and they are absolutely no proof whatever of a normal and non-pathological tendency to the inheritance of acquired characters4 ,those who accept ,darwin's special explanation of the supposed inheritance of mutilations1 ought to notice that his explanation applies equally well under a theory which is strongly adverse to use-inheritance--namely1 ,galton's idea of the sterilization and complete using up of otherwise reproductive matter in the growth and maintenance of the personal structure4 ,darwin's explanation of inherited mutilations--which1 as he notes1 occur especially or perhaps exclusively when the injury has been followed by disease#ef--;is that all the representative gemmules which would develop or repair or reproduce the injured part are attracted to the diseased surface during the reparative process and are there destroyed by the morbid action4#eg ,hence they cannot reproduce the part in offspring4 ,this explanation by no means implies that mutilation would usually affect the offspring4 ,on the contrary1 in all ordinary cases of mutilation the purely atavistic elements or gemmules would be set free from any modifying influence of the non-existent or mutilated part4 ,the gemmules--as in ,galton's theory of heredity and with neuter insects--might be perfectly independent of pangenesis and the normal inheritance of acquired characters4 ,such self-multiplying gemmules without pangenesis would enable us to understand both the excessive weakness or non-existence of normal use-inheritance1 and the excessive strength and abruptness of the effect of their partial destruction under special pathological conditions4 ,the series of epileptic phenomena that can be excited by tickling a certain part of the cheek and neck of the adult guinea-pig during the growth and rejoining of the ends of the severed nerve1 are said to be repeated with striking accuracy of detail in the young who inherit mutilated toes2 but as epilepsy is often due to some one exciting cause or morbid condition1 the single transmission of a highly morbid condition of the system might easily reproduce the whole chain of consequences and might also have caused the loss of toes4 ,the particulars of the guinea-pig cases are very inadequately recorded1#eh but the results are so anomalous#ei that ,brown-,sequard's own conclusion is that the epilepsy and the inherited injuries are not directly transmitted1 but that what is transmitted is the morbid state of the nervous system4 ,he thinks that the missing toes may possibly be exceptions to this conclusion1 but the other facts only imply the transmission of a morbid state of the sympathetic or sciatic nerve or of a part of the medulla oblongata4 ,until we can tell what is transmitted1 we are not in a position to determine whether there is any true inheritance or only an exaggerated simulation of it under peculiar circumstances4 ,when the actual observers believe that the mutilations and epilepsy are not the cause of their own repetition1 and when these observers guard themselves by such phrases as1 if any conclusion can at present be drawn from those facts1 we who have only incomplete reports to guide us may well be excused if we preserve an even more pronounced attitude of caution and reserve4#fj ,the morbid state of the system may be wholly due to general injury of the germs rather than to specific inheritance4 ,weismann suggests that the morbid condition of the nervous system may be due to some infection such as might arise from microbes1 which find a home in the mutilated and disordered nervous system in the parent1 and subsequently transmit themselves to the offspring through the reproductive elements1 as the infections of various diseases appear to do--the muscardine silkworm disease in particular being known to be conveyed to offspring in this manner4 ,but whether we can discover the true explanation or not1 inherited mutilations can hardly be accounted for as the result of a general tendency to inherit acquired modifications4 ,how could a factor which seems to be totally inoperative in cases of ordinary mutilation1 and only infinitesimally operative in transmitting the normal effects of use and disuse1 suddenly become so powerful as to completely overthrow atavism1 and its own tendency to transmit the non-mutilated type of one of the parents and of the non-mutilated type presented by the injured parent in earlier life8 ,does not so striking and abrupt an intensification of its usually insignificant power demand an explanation widely different from that which might account for the extremely slow and slight inheritance of the normal effects of use and disuse8 ,surely it would be better to suspend one's judgment as to the true explanation of highly exceptional and purely pathological cases rather than resort to an hypothesis that creates more difficulties than it solves4 ,,the ,,motmot',s ,,tail4 ,the narrowing of the long central tail feathers of the motmot is attributed to the inherited effects of habitual mutilation 7,descent of ,man1 pp4 #chd1 #fjc74 ,but in the specimens at ,south ,kensington#fa the narrowness extends upwards much beyond the habitually denuded part1 and the broadened end is the broadest part of the whole feather4 ,if the inherited effect of an inch or two of denudation extends from three to six inches upwards1 why has it not also extended two inches downwards so as to narrow the broadened end8 ,the narrowness seems to be a mainly relative or negative effect produced by the broadening out of a long tapering feather at its end under the influence of sexual selection4 ,several other birds have similarly narrowed or spoon-shaped feathers and do not bite them4 ,is it not more feasible to suppose that this attractive peculiarity first suggested its artificial intensification1 than to suppose that the bird began nibbling without any definite cause8 ,sexual selection would then encourage the habit4 ,anyhow1 it is as impossible to show that the mutilation preceded the narrowing as it is to show that tonsure preceded baldness4 ,,other ,,inherited ,,injuries ,,mentioned ,,by ,,darwin4 ,darwin quotes some cases from ,dr4 ,prosper ,lucas's long but weak and unsatisfactory list of inherited injuries4#fb ,but ,lucas was somewhat credulous4 ,one of his cases is that many girls were born in ,london without mammae through the injurious effect of certain corsets on the mothers4 ,he also gives a long account of a ,jew who could read through the thick covers of a book1 and whose son inherited this hyperaesthesia of the sense of sight in a still more remarkable degree 7i4 #aac-aai74 ,evidently ,lucas's cases cannot be accepted without some amount of reserve4 ,the cases of the three calves which inherited the one-horned condition of the cow1 the two sons who inherited a father's crooked finger1 and the two sons who were microphthalmic on the same side as their father had lost an eye1 may be due to mere coincidence2 or an inherited constitutional tendency or liability might lead to somewhat similar results in parent and offspring#fc--;just as the tendency to certain fatal diseases or to suicide may produce similar results in father and son1 although the artificially-produced hanging or apoplexy obviously cannot be directly transmitted4 ,that more than one of the offspring was affected does not render the chances against coincidence almost infinitely great1 as ,darwin mistakenly supposes4 ,it frequently occurs that a man's sons or daughters may all exhibit either a latent or a newly-developed congenital peculiarity previously unknown2#fd and the coincidence may merely be that one of the parents accidentally suffered a similar kind of injury--a kind of coincidence which must of course occasionally occur1 and which may have been partly caused by a latent tendency4 ,the chances against coincidence are indeed great1 but the cases appear to be correspondingly rare4 ,darwin acknowledges that many supposed instances of inherited mutilation may be due to coincidence2 and there is apparently no more reason for attributing inherited scars1 c41 to any special form of heredity than to the effect of the mother's imagination on the unborn babe--a popular but fallacious belief in corroboration of which far more alleged instances could be collected than of the inheritance of injuries4 ,as an instance of the coincidences that occur1 ,i may mention that a friend of mine has a daughter who was born with a small hole in one ear1 just as if it were already pierced for the earring which she has since worn in it4 ,i suppose1 however1 that no one will venture to claim this as an instance of the inheritance of a mutilation practised by female ancestors1 especially as such holes are not altogether unknown or inexplicable1 though very rarely occurring low down in the lobe of the ear4#fe ,many cases are known of the inheritance of mutilations or malformations arising congenitally from some abrupt variation in the reproductive elements4 ,in such cases as the one-eared rabbits1 the two-legged pigs1 the three-legged dogs1 the one-horned stags1 hornless bulls1 earless rabbits1 lop-eared rabbits1 tailless dogs1 c41 if the father or the mother or the embryo had suffered from some accident or disease which might plausibly have been assigned as the cause of the original malformation1 these transmitted defects would readily be cited as instances of the inheritance of an accidentally-produced modification4 ,the inheritance of exostoses on horses' legs may be the inheritance of a constitutional tendency rather than of the effect of the parents' hard travelling4 ,horses congenitally liable to such formations would transmit the liability1#ff and this might readily be mistaken for inheritance of the results of the liability4 ,an apparent increase in this liability might arise from greater attention being now paid to it1 or from increased use of harder roads2 or a real increase might be due to panmixia and some obscure forms of correlation4 ,,quasi-,,inheritance4 ,of course artificially-caused ill-health or weakness in parents will tend in a general way to injure the offspring4 ,but deterioration thus caused is only a form of quasi-inheritance1 as ,i should prefer to call it4 ,semi-starvation in a new-born babe is not truly inherited from its half-starved mother1 but is the direct result of insufficient nourishment4 ,the general welfare of germs--as of parasites--is necessarily bound up with that of the organism which feeds and shelters them1 but this is not heredity1 and is quite irrelevant to the question whether particular modifications are transmitted or not4 ,another form of quasi-inheritance is seen in the communication of certain infections to offspring4 ,not being transmitted by the action of the organism so much as in defiance of it1 such diseases are not truly hereditary1 though for convenience' sake they are usually so described4 ,a perversion or prevention of true inheritance is also seen in the action of alcohol1 or excessive overwork1 or any other cause which by originating morbid conditions in individuals may also injure the reproductive elements4 ,these forms of quasi-inheritance are1 of course1 highly important so far as the improvement of the race is concerned4 ,so1 too1 is the fact that improved or deteriorated habits and thoughts are transmitted by personal teaching and influence and are cumulative in their effect4 ,but all this must not be confounded with the inheritance of acquired characters4 ,cases of quasi-inheritance may perhaps be most readily distinguished from cases of true inheritance by the time test4 ,when a modification acquired in adult life is promptly communicated to the child in early life or from birth1 it may rightly be suspected that the inheritance1 like that of money or title1 is not truly congenital1 but is extraneous or even anti-congenital in its nature4 ,judged by such a standard1 the inherited injuries in ,brown-,sequard's guinea-pigs are only exceptional cases of quasi-inheritance1 and are not necessarily indicative of any general rule affecting true inheritance4 ,,footnotes3 #ed ,a very able anatomist of my acquaintance denies the inheritance of mutilations and injuries1 although he strongly believes in the inheritance of the effects of use and disuse4 #ee ,variation of ,animals and ,plants under ,domestication1 i4 #dfg-dfi4 ,lost toes were only seen by ,dr4 ,dupuy in three young out of two hundred4 ,obersteiner found that most of the offspring of his epileptic guinea-pigs were injuriously affected1 being weakly1 small1 paralysed in one or more limbs1 and so forth4 ,only two were epileptic1 and both were weakly and died early 7,weismann's ,essays1 p4 #caa74 ,a morbid condition of the spinal cord might affect the hind limbs especially 7as in paraplegia7 and might occasionally cause loss of toes in the embryo by preventing development or by ulceration4 ,brown-,sequard does not say that the defective feet were on the same side as in the parents 7,lancet1 ,jan41 #ahge1 pp4 #g1 #h74 #ef ,variation of ,animals and ,plants under ,domestication1 ii4 #eg4 #eg ,ibid41 ii4 #cib4 ,perhaps it might be better to suppose that the best gemmules were sacrificed in repairing the injured nerve1 and hence only inferior substitutes were left to take their place1 and could only imperfectly reproduce the injured part of the nervous system in offspring4 #eh ,hence perhaps ,mr4 ,spencer's error in representing the epileptic liability as permanent and as coming on after healing 7,factors of ,organic ,evolution1 p4 #bg74 #ei ,it is not claimed that the imperfect foot was on the same side of the body as in the parent1 and where parents had lost all the toes of a foot1 or the whole foot1 the few offspring affected usually had lost only two toes out of the three1 or only a part of one or two or three toes4 ,sometimes the offspring had toes missing on both hind feet1 although the parent was only affected in one4 ,one diseased ear and eye in the parent was generally or always succeeded by two equally affected ears and eyes in the offspring 7cf4 ,pop4 ,science ,monthly1 ,new ,york1 xi4 #ccd74 ,the important law of inheritance at corresponding periods was also set aside4 ,gangrene or inflammation commenced in both ears and both eyes soon after birth 7pointing possibly to infection of some kind72 the epileptic period commenced perhaps two months or more after birth1 while the loss of toes had occurred before birth4 ,in no case1 as ,weismann points out1 is the original mutilation of the nervous system ever transmitted4 ,even where an extirpated ganglion was never regenerated in the parent1 the offspring always regained the part in an apparently perfect condition4 ,on the whole the conflicting results ought to be as puzzling to those who may attribute them to a universal tendency to inherit the exact condition of parents as they are to those who1 like myself1 are sceptical as to the existence of such a law or tendency4 #fj ,the various results need to be fully and impartially recorded1 and they should also be well tested and confirmed in proportion as they appear improbable and contrary to general experience4 ,professor ,romanes has been carrying out the necessary experiments for some time past4 #fa ,natural ,history ,museum1 central hall1 third recess on the left4 #fb ,traite de l',heredite1 ii4 #dhi2 ,variation of ,animals and ,plants under ,domestication1 i4 #dfi4 ,if injuries are inherited1 why has the repeated rupture of the hymen produced no inherited effect8 #fc ,compare the three cases of crooked fingers given in ,variation of ,animals and ,plants under ,domestication1 ii4 #ee1 #bdj4 #fd ,ibid41 i4 #dfj4 ,thus1 where two brothers married two sisters all the seven children were perfect albinos1 although none of the parents or their relatives were albinos4 ,in another case the nine children of two sound parents were all born blind 7ii4 #cbb74 #fe ,see pp4 #agi-ahb1 ,evolution and ,disease1 by ,j4 ,bland ,sutton1 to whom and to our mutual friend ,dr4 ,d4 ,thurston ,i am indebted for information on various points4 #ff ,variation of ,animals and ,plants under ,domestication1 ii4 #bij2 i4 #ded4 ,,miscellaneous ,,considerations4 ,,true ,,relation ,,of ,,parents ,,and ,,offspring4 ,it is difficult to entirely free ourselves from the flattering and almost universal idea that parents are true originators or creators of copies of themselves4 ,but the main truth1 if not the whole truth1 is that they are merely the transmitters of types of which they and their offspring are alike more or less similarly moulded resultants4 ,a parent is a trustee4 ,he transmits1 not himself and his own modifications1 but the stock1 the type1 the representative elements1 of which he is a product and a custodian in one4 ,it seems probable that he has no more definite or particulate influence over the reproductive elements within him than a mother over the embryo or a vessel over its cargo4 ,parent and offspring are like successive copies of books printed from the same type4 ,a battered letter in the type will display its effects in both earlier and later copies alike1 but a purely extraneous or acquired flaw in the first copy is not necessarily repeated in subsequent copies4 ,unlike printer's type1 however1 the material source of heredity is of a fluctuating nature1 consisting of competing elements derived from two parents and from innumerable ancestors4 ,galton compares parent and child to successive pendants on the same chain4 ,weismann likens them to successive offshoots thrown up by a long underground root or sucker4 ,such comparisons indicate the improbability of acquired modifications being transmitted to offspring4 ,that parts are developed in offspring independently of those parts in parents is clear4 ,mutilated parents transmit parts which they do not possess4 ,the offspring of young parents cannot inherit the later stages of life from parents who have not passed through them4 ,cases of remote reversion or atavism show that ancestral peculiarities can transmit themselves in a latent or undeveloped condition for hundreds or thousands of generations4 ,many obvious facts compelled ,darwin to suppose that vast numbers of the reproductive gemmules in an individual are not thrown off by his own cells1 but are the self-multiplying progeny of ancestral gemmules4 ,galton restricts the production of gemmules by the personal structure to a few exceptional cases1 and would evidently like to dispense with pangenesis altogether1 if he could only be sure that acquired characters are never inherited4 ,weismann entirely rejects pangenesis and the inheritance of acquired characters4 ,this enables him to explain heredity by his theory of the ,continuity of the ,germ-plasm4#fg ,parent and offspring are alike successive products or offshoots of this persistent germ-substance1 which obviously would not be correspondingly affected by modifications of parts in parents1 and so would render the transmission of acquired characters impossible4 ,,inverse ,,inheritance4 ,mr4 ,galton contends that the reproductive elements become sterile when used in forming and maintaining the individual1 and that only a small proportion of them are so used4#fh ,he holds that the next generation will be formed entirely1 or almost entirely1 from the residue of undeveloped germs1 which1 not having been employed in the structure and work of the individual1 have been free to multiply and form the reproductive elements whence future individuals are derived4 ,hence the singular inferiority not infrequently displayed by the children of men of extraordinary genius1 especially where the ancestry has been only of a mediocre ability4 ,the valuable germs have been used up in the individual1 and rendered sterile in the structure of his person4 ,hence1 too1 the strong tendency to deterioration in the transmission of every exceptionally gifted race4 ,mr4 ,galton's hypothesis explains the fact of certain diseases skipping one or more generations1 and it agrees singularly well with many classes of fact2 and it is strongly opposed to the theory of use-inheritance4 ,the elements which are used die almost universally without germ progeny3 the germs which are not used are the great source of posterity4 ,hence1 when the germs or gemmules which achieve development are either better or worse than the residue1 the qualities transmitted to offspring will be of an inverse character4 ,if brain-work attracts1 develops and sterilizes the best gemmules1 the ultimate effect of education on the intellect of posterity may differ from its immediate effect4 ,,early ,,origin ,,of ,,the ,,ova4 ,as the ova are formed at as early a period as the rest of the maternal structure1 ,galton notices that it seems improbable that they would be correspondingly affected by subsequent modifications of parental structure4 ,of course it is not certain that this is a valid argument4 ,we know that the paternal half of the reproductive elements does not enter the ovum till a comparatively late stage in its history1 and it is quite possible that maternal elements or gemmules may also enter the ovum from without4 ,if reproductive elements were confined to one special part or organ1 we should be unable to explain the reproduction of lost limbs in salamanders1 and the persistent effect of intercrossing on subsequent issue by the same mother1 and the propagation of plants from shoots1 or of the begonia from minute fragments of leaves1 or the development of small pieces of water-worms into complete animals4 ,,marked ,,effects ,,of ,,use ,,and ,,disuse ,,on ,,the ,,individual4 ,these are1 to some extent1 an argument against the cumulative inheritance of such effects4 ,when a nerve atrophies from disuse1 or a duct shrivels1 or bone is absorbed1 or a muscle becomes small or flabby1 it proves1 so far1 that the average effect of use through enormous ages is not transmitted4 ,when the fibula of a dog's leg thickens by #djj per cent4 to a size equal to or greater than that of the removed tibia which previously did the work1#fi it shows that in spite of disuse for countless generations1 the almost filiform bone has retained a potentiality of development which is fully equal to that possessed by the larger one which has been constantly used4 ,when1 after being reared on the ailanthus1 the caterpillars of the ,bombyx hesperus die of hunger rather than return to their natural food1 the inherited effect of ancestral habit does not seem to be particularly strong4 ,neither is there any strongly-inherited effect of long-continued ancestral wildness in many animals which are easily tamed4 ,,would ,,natural ,,selection ,,favour ,,use-,,inheritance8 ,if use-inheritance is really one of the factors of evolution1 it is certainly a subordinate one1 and an utterly helpless one1 whenever it comes into conflict with the great ruling principle of ,selection4 ,would this dominant cause of evolution have favoured a tendency to use-inheritance if such had appeared1 or would it have discouraged and destroyed it8 ,we have already seen that use-inheritance is unnecessary1 since natural selection will be far more effective in bringing about advantageous modifications2 and if it can be shown that use-inheritance would often be an evil1 it then becomes probable that on the whole natural selection would more strongly discourage and eliminate it as a hostile factor than it might occasionally favour such a tendency as a totally unnecessary aid4 ,,use-,,inheritance ,,an ,,evil4 ,use-inheritance would crudely and indiscriminately proportion parts to actual work done--or rather to the varying nourishment and growth resulting from a multiplicity of causes--and this in its various details would often conflict most seriously with the real necessities of the case1 such as occasional passive strength1 or appropriate shape1 lightness and general adaptation4 ,if its accumulated effects were not corrected by natural or sexual selection1 horns and antlers would disappear in favour of enlarged hoofs4 ,the elephant's tusks would become smaller than its teeth4 ,men would have callosities for sitting on1 like certain monkeys1 and huge corns or hoofs for walking on4 ,bones would often be modified disastrously4 ,thus the condyle of the human jaw would become larger than the body of the jaw1 because as the fulcrum of the lever it receives more pressure4 ,some organs 7like the heart1 which is always at work7 would become inconveniently or unnecessarily large4 ,other absolutely indispensable organs1 which are comparatively passive or are very seldom used1 would dwindle until their weakness caused the ruin of the individual or the extinction of the species4 ,in eliminating various evil results of use-inheritance1 natural selection would be eliminating use-inheritance itself4 ,the displacement of ,lamarck's theory by ,darwin's shows that the effects of use-inheritance often differ from those required by natural selection2 and it is clear that the latter factor must at least have reduced use-inheritance to the very minor position of comparative feebleness and harmlessness assigned to it by ,darwin4 ,use-inheritance would be ruinous through causing unequal variation in co-operative parts--of which ,mr4 ,spencer may accept his own instances of the jaws and teeth1 and the cave-crab's lost eyes and persistent eye-stalks1 as typical examples4 ,that the variation would be unequal seems almost self-evident from the varying rapidity and extent of the effects of use and disuse on different tissues and on different parts of the general structure4 ,the optic nerve may atrophy in a few months from disuse consequent on the loss of the eye4 ,some of the bones of the rudimentary hind legs of the whale are still in existence after disuse for an enormous period4 ,evidently use-inheritance could not equally modify the turtle and its shell1 or the brain and its skull2 and in minor matters there would be the same incongruity of effect4 ,thus1 if the molar teeth lengthened from extra use the incisors could not meet4 ,unequal and indiscriminate variation would throw the machinery of the organism out of gear in innumerable ways4 ,use-inheritance would perpetuate various evils4 ,we are taught1 for instance1 that it perpetuates short-sight1 inferior senses1 epilepsy1 insanity1 nervous disorders1 and so forth4 ,it would apparently transmit the evil effects of over-exertion1 disuse1 hardship1 exposure1 disease and accident1 as well as the defects of age or immaturity4 ,would it not be better on the whole if each individual took a fresh start as far as possible on the advantageous typical lines laid down by natural selection8 ,through the long stages of evolution from primaeval protoplasm upwards1 such species as were least affected by use-inheritance would be most free to develop necessary but seldom-used organs1 protective coverings such as shells or skulls1 and natural weapons1 defences1 ornaments1 special adaptations1 and so forth2 and this would be an advantage--for survival would obviously depend on the importance of a structure or faculty in deciding the struggle for existence and reproduction1 and not on the total amount of its using or nourishment4 ,if natural selection had on the whole favoured this officious ally and frequent enemy1 surely we should find better evidence of its existence4 ,without laying undue stress upon the evil effects of use-inheritance1 a careful examination of them in detail may at least serve to counter-balance the optimistic a priori arguments for belief in that plausible but unproven factor of evolution4 ,the benefits derivable from use-inheritance are largely illusory4 ,the effects of use1 indeed1 are generally beneficial up to a certain point2 for natural selection has sanctioned or evolved organs which possess the property or potentiality of developing to the right extent under the stimulus of use or nourishment4 ,but use-inheritance would cumulatively alter this individual adaptability1 and would tend to fix the size of organs by the average amount of ancestral use or disuse rather than by the actual requirements of the individual4 ,of course under changed conditions involving increased or lessened use of parts it might become advantageous2 but even here it may prove a decided hindrance to adaptive evolution in some respects as well as an unnecessary aid in others4 ,thus in the case of animals becoming heavier1 or walking more1 it would lengthen the legs although natural selection might require them to be shortened4 ,in the ,aylesbury duck and the ,call duck1 if use-inheritance has increased the dimensions of the bones and tendons of the leg1 natural selection has had to counteract this increase so far as length is concerned1 and to effect #h per cent4 of shortening besides4 ,if use-inheritance thickens bones without proportionally lengthening them1 it would hinder rather than help the evolution of such structures as the long light wings of birds1 or the long legs and neck of the giraffe or crane4 ,,varied ,,effects ,,of ,,use ,,and ,,disuse4 ,the changes which we somewhat roughly and empirically group together as the effects of use and disuse are of widely diverse character4 ,thus bone1 as the physiological fact1 thickens under alternations of pressure 7and the consequent increased flow of nourishment71 but atrophies under a steadily continued pressure2 so that if the use of a bone involved continuous pressure1 the effect of such use would be a partial or total absorption of that bone4 ,darwin shows that bone lengthens as well as thickens from carrying a greater weight1 while tension 7as seen in sailors' arms1 which are used in pulling7 appears to have an equally marked effect in shortening bones 7,descent of ,man1 p4 #cb74 ,thus different kinds of use may produce opposite results4 ,the cumulative inheritance of such effects would often be mischievous4 ,the limbs of the sloth and the prehensile tail of the spider monkey would continually grow shorter1 while the legs of the evolving elephant or rhinoceros might lengthen to an undesirable extent4 ,such cumulative tendencies of use-inheritance1 if they exist1 are obviously well kept under by natural selection4 ,although the ultimate effect of use is generally growth or enlargement through increased flow of blood1 the first effect usually is a loss of substance1 and a consequent diminution of size and strength4 ,when the loss exceeds the growth1 use will diminish or deteriorate the part used1 while disuse would enlarge or perfect it4 ,teeth1 claws1 nails1 skin1 hair1 hoofs1 feathers1 c41 may thus be worn away faster than they can renew themselves4 ,but this wearing away usually stimulates the repairing process1 and so increases the rate of growth2 that is1 it will increase the size produced1 if not the size retained4 ,which effect of use does use-inheritance transmit in such cases--the increased rate of growth1 or the dilapidation of the worn-out parts8 ,we can hardly suppose that both these effects of use will be inherited4 ,would shaving destroy the beard in time or strengthen it8 ,will the continued shearing of sheep increase or lessen the growth of wool8 ,what will be the ultimate effect of plucking geese's quills1 and of the eider duck's abstraction of the down from her breast8 ,if the mutilated parts grow stronger or more abundantly1 why were the motmot's feathers alleged to be narrowed by the inherited effects of ancestral nibbling8 ,the use or work or function of muscles1 nerves1 bones1 teeth1 skin1 tendon1 glands1 ducts1 eyes1 blood corpuscles1 cilia1 and the other constituents of the organism1 is as widely different as the various parts are from each other1 and the effects of their use or disuse are equally varied and complicated4 ,,use-,,inheritance ,,implies ,,pangenesis4 ,how could the transmission of these varied effects to offspring be accounted for8 ,is it possible to believe1 with ,mr4 ,spencer1 that the effects of use and disuse on the parts of the personal structure are simultaneously registered in corresponding impressions on the seminal germs8 ,must we not feel1 with ,darwin apparently1#gj that the only intelligible explanation of use-inheritance is the hypothesis of ,pangenesis1 according to which each modified cell1 or physiological unit1 throws off similarly-modified gemmules or parts of itself1 which ultimately reproduce the change in offspring8 ,if we reject pangenesis1 it becomes difficult to see how use-inheritance can be possible4 ,,pangenesis ,,improbable4 ,the more important and best-known phenomena of heredity do not require any such hypothesis1 and leading facts 7such as atavism1 transmission of lost parts1 and the general non-transmission of acquired characters7 are so adverse to it that ,darwin has to concede that many of the reproductive gemmules are atavistic1 and that by continuous self-multiplication they may preserve a practical continuity of germ-substance1 as ,weismann would term it4 ,the idea that the relationship of offspring to parent is one of direct descent is1 as ,galton tells us1 wholly untenable2 and the only reason he admits some supplementary traces of pangenesis into his ,theory of ,heredity1#ga is that he may thus account for the more or less questionable cases of the transmission of acquired characters4 ,but there appears to be no necessity even for this concession4 ,we ought therefore to dispense with the useless and gratuitous hypothesis that cells multiply by throwing off minute self-multiplying gemmules1 as well as by the well-known method of self-division4 ,if pangenesis occurs1 the transmission of acquired characters ought to be a prominent fact4 ,the size1 strength1 health and other good or evil qualities of the cells could hardly fail to exercise a marked and corresponding effect upon the size and quality of the reproductive gemmules thrown off by those cells4 ,the direct evidence tends to show that these free gemmules do not exist4 ,transfusion of blood has failed to affect inheritance in the slightest degree4 ,pangenesis1 with its attraction of gemmules from all parts of the body into the germ-cells1 and the free circulation of gemmules in the offspring till they hit upon or are attracted by the particular cell or cells1 with which alone they can readily unite1 seems a less feasible theory and less in conformity with the whole of the facts than an hypothesis of germ-continuity which supposes that the development of the germ-plasm and of the successive self-dividing cells of the body proceeds from within4 ,darwin's keen analogy of the fertilization of plants by pollen renders development from without conceivable1 but as there are no insects to convey gemmules to their destination1 each kind of gemmule would have to be exceedingly numerous and easily attracted from amongst an inconceivable number of other gemmules4 ,arguments against pangenesis can also be drawn from the case of neuter insects--a fact which seems to have escaped ,darwin's notice1 although he had seen how strongly that case was opposed to the doctrine which is the essential basis of the theory of pangenesis4 ,,spencer',s ,,explanation ,,of ,,use-,,inheritance4 ,mr4 ,spencer's explanation of the inheritance of the effects of use and disuse 7p4 #cf7 is that while generating a modified consensus of functions and of structures1 the activities are at the same time impressing this modified consensus on the sperm-cells and germ-cells whence future individuals are to be produced--a proposition which reads more like metaphysics than science4 ,difficult to understand or believe in ordinary instances1 such consensus-inheritance seems impossible in cases like that of the hive-bee4 ,can we suppose that the consensus of the activities of the working bee impresses itself on the sperm-cells of the drones and on the germ-cells of the carefully secluded queen8 ,buechner thinks so1 for he says3 ,although the queens and drones do not now work1 yet the capacities inherited from earlier times still remain to them1 especially to the former1 and are kept alive and fresh by the impressions constantly made upon them during life1 and they are thus in a position to transmit them to posterity4 ,surely it is better to abandon a cherished theory than to be compelled to defend it by explanations which are as inconsistent as they are inadequate4 ,new capacities are developed as well as old ones kept fresh4 ,the massacre or expulsion of the drones would have to impress itself on the germ-cells of an onlooking queen1 and the imprisonment of the queen on the sperm-cells of the drones--and in such a way1 moreover1 as to be afterwards developed into action in the neuters only4 ,and use-inheritance all the while is being thoroughly overpowered by impression-inheritance--by the full transmission of that which is merely seen in others6 ,if such a law prevails1 one may feel cold because an ancestor thought of the frosty ,caucasus4 ,none of this absurdity would arise if it were clearly seen that a parent is only a trustee--that transmission and development are perfectly distinct--that parental modifications are irrelevant to those transmitted to offspring4 ,,footnotes3 #fg ,essays on ,heredity1 p4 #ajd4 ,weismann's theory is clear1 simple and convenient1 but incomplete2 for1 unlike ,darwin's theory of pangenesis1 it scarcely attempts any real explanation of the extremely complex potentialities possessed by the reproductive elements4 ,perhaps we might retain ,darwin's self-multiplying gemmules without supposing them to be thrown off by the cells1 which will no longer be credited with two modes of multiplication4 ,these minute germs or gemmules may have been evolved by natural selection playing upon the sample germs that achieve development2 and they may exist either separately1 or 7preferably but perhaps not invariably7 in aggregates to form ,weismann's germ-plasm4 #fh ,contemporary ,review1 ,dec41 #ahge1 p4 #hh4 #fi ,variation of ,animals and ,plants under ,domestication1 ii4 #bhf4 #gj ,variation of ,animals and ,plants under ,domestication1 ii4 #chh1 #cih1 #cfg2 ,life and ,letters1 iii4 #dd4 #ga ,contemporary ,review1 ,dec41 #ahge1 pp4 #id1 #ie4 ,,conclusions4 ,,use-,,inheritance ,,discredited ,,as ,,unnecessary1 ,,unproven1 ,,and ,,improbable4 ,general experience teaches that acquired characters are not usually inherited2 and investigation shows that the apparent exceptions to this great rule are probably fallacious4 ,even the alleged instances of use-inheritance culled by such great and judicious selectors as ,darwin and ,spencer break down upon examination2 for they can be better explained without use-inheritance than with it4 ,on the other hand1 the adverse facts and considerations are almost strong enough to prove the actual non-existence of such a law or tendency4 ,there is no need to undertake the apparently impossible task of demonstrating an absolute negative4 ,it will be enough to ask that the ,lamarckian factor of use-inheritance shall be removed from the category of accredited factors of evolution to that of unnecessary and improbable hypotheses4 ,the main explanation or source of the fallacy may be found in the fact that natural selection frequently imitates some of the more obvious effects of use and disuse4 ,,modern ,,reliance ,,on ,,use-,,inheritance ,,misplaced4 ,modern philanthropy--so far at least as it ever studies ultimate results--constantly relies on this ill-founded belief as its justification for ignoring the warnings of those who point out the ultimately disastrous results of a systematic defiance or reversal of the great law of natural selection4 ,this reliance finds strong support in ,mr4 ,spencer's latest teachings1 for he holds that the inheritance of the effects of use and disuse takes place universally1 and that it is now the chief factor in the evolution of civilized man 7pp4 #ce1 #gd1 iv7--natural selection being quite inadequate for the work of progressive modification4 ,practically he abandons the hope of evolution by natural selection1 and substitutes the ideal of a nation being modified en masse by transmission of the effects of its institutions and habits4 ,use-inheritance will mould its members far more rapidly and comprehensively than can be effected by the survival of the fittest alone4 ,but could we rely upon the aid of use-inheritance if it really were a universal law and not a mere simulation of one8 ,let us consider some of the features of this alleged factor of evolution1 seeing that it is henceforth to be our principal means of securing the improvement of our species and our continued adaptation to the changing conditions of a progressive civilization4 ,it is curiously uncertain and irregular in its action4 ,it diminishes or abolishes some structures 7such as jaws or eyes7 without correspondingly diminishing or abolishing other equally disused and closely related parts 7such as teeth1 or eye-stalks74 ,it thickens ducks' leg-bones while allowing them to shorten4 ,it shortens the disused wing-bones of ducks and the leg-bones of rabbits while allowing them to thicken2 and yet in other cases it greatly reduces the thickness of bones without shortening them4 ,it transmits tameness most powerfully in an animal which usually cannot acquire it4 ,it aids in webbing the feet of water-dogs1 but fails to web the feet of the water-hen or to remove the web in the feet of upland geese4#gb ,it allows the disused fibula to retain a potentiality of development fully equal to that possessed by the long-used tibia4 ,it lengthens legs because they are used in supporting the body1 and shortens arms because they are used in pulling4 ,whether it enlarges brain if used in one way and diminishes it if used in another1 we cannot tell2 but it must obviously deaden nervous sensibilities in some cases and intensify them in others4 ,it enlarges hands long before they are used1 and thickens soles long before the time for walking on them4 ,at the same time1 as if by an oversight1 it so delays its transmission of the habit of walking on these thickened soles1 that the gradual and tedious acquisition of the non-transmitted habit costs the infant much time and trouble and often some pain and danger4 ,yet where aided by natural selection1 as with chickens and foals1 it transmits the habit in wonderful perfection and at a remarkably early date4 ,it transmits new paces in horses in a single generation1 but fails to perpetuate the songs of birds4 ,it modifies offspring like parents1 and yet allows the formation of two reproductive types in plants1 and of two or more types widely different from the parents in some of the higher insects4 ,it is said to be indispensable for the co-ordinated development of man and the giraffe and the elk1 but appears to be unnecessary for the evolution and the maintenance of wonderful structures and habits and instincts in a thousand species of ants and bees and termites4 ,it is the only possible means of complex evolution and adaptation of co-operative parts1 and yet in ,mr4 ,spencer's most representative case it renders such important parts as teeth and jaws unsuited for each other1 and is said to ruin the teeth by the consequent overcrowding and decay4 ,it survives amidst a general lack of recognised evidence1 and only seems to act usefully and healthily and regularly in quarters where it can least easily be distinguished from other more powerful and demonstrable factors of evolution4 ,so little does it care to display its powers where they would be easily verifiable as well as useful that practical breeders ignore it4 ,so slight is its independent power that it seems to allow natural selection or sexual selection or artificial selection to modify organisms in sheer defiance of its utmost opposition1 just as readily as they modify organisms in other directions with its utmost help4 ,if it partially perpetuates and extends the pecked-out indentations in the motmot's tail feathers1 it on the other hand fails to transmit the slightest trace of mutilation in an almost infinite number of ordinary cases1 and even where the mutilation is repeated for a hundred generations2 and it apparently repairs rather than transmits the ordinary and oft-repeated losses caused by plucking hair1 down and feathers1 and the wear and tear of claws1 teeth1 hoofs and skin4 ,it is often mischievous as well as anomalous in its action4 ,under civilization with its division of labour1 the various functions of mind and body are very unequally exercised4 ,there is overwork or misuse of one part and disuse and neglect of others1 leading to the partial breakdown or degeneration of various organs and to general deterioration of health through disturbed balance of the constitution4 ,the brain1 or rather particular parts of it1 are often over-stimulated1 while the body is neglected4 ,in many ways education and civilization foster nervousness and weakness1 and undermine the rude natural health and spirits of the human animal4 ,alcohol1 tobacco1 tea1 coffee1 extra brain work1 late hours1 dissipation1 overwork1 indoor life1 division of labour1 preservation of the weak1 and many other causes1 all help to injure the modern constitution2 so that the prospect of cumulative intensification of these evils by the additional influence of use-inheritance is not an encouraging one4 ,it is true that modern progress and prosperity are improving the people in various respects by their direct action2 but if use-inheritance has any share in effecting this improvement it must also transmit increased wants and more luxurious habits1 together with such evils as have already been referred to4 ,as depicted by its defenders1 use-inheritance transmits evils far more powerfully and promptly than benefits4 ,it transmits insanity and shattered nerves rather than the healthy brain which preceded the breakdown4 ,it perpetuates1 and cumulatively intensifies1 a deterioration in the senses of civilized men1 but it fails to perpetuate the rank vigour of various plants when too well nourished1 or the flourishing condition of various animals when too fat or when tamed4 ,it already transmits the short-sight caused by so modern an art as watchmaking1 but so fails to transmit the long-practised art of seeing 7as it does of walking and talking7 that vision is worse than useless to a man until he gradually acquires the necessary but non-transmitted associations of sensation and idea by his own experience4 ,in a well-known case1 a blind man on gaining his sight by an operation said that all objects seemed to touch his eyes1 as what he felt did his skin--so little had the universal experience of countless ages impressed itself on his faculties4 ,under normal healthy conditions use-inheritance is so slow in its action that several generations must elapse before it produces any appreciable effect1 and then that effect is only precisely what selection might be expected to bring about without its aid4 ,strong for evil and slow for good1 it can convey epilepsy promptly in guinea pigs1 but transmits the acquirements of genius so poorly that our best student of the heredity of genius has to account for the frequent and remarkable deterioration of the offspring by a theory which is strongly hostile to use-inheritance4 ,it would tend to make organisms unworkable by the excessive differences in its rate and manner of action on co-operative parts1 and by adapting these parts to the total amount of nourishment received rather than to occasional necessity or actual usefulness4 ,it would tend to stereotype habits and convert reason into instinct4 ,how then can we rely upon use-inheritance for the improvement of the race8 ,even if it is not a sheer delusion1 it may be more detrimental as a positive evil than it is advantageous as an unnecessary benefit2 and as a normal modifying agent it is miserably weak and untrustworthy in comparison with the powerful selective influences by which nature and society continually and inevitably affect the species for good or for evil4 ,the effects of use and disuse--rightly directed by education in its widest sense--must of course be called in to secure the highly essential but nevertheless superficial1 limited1 and partly deceptive improvement of individuals and of social manners and methods2 but as this artificial development of already existing potentialities does not directly or readily tend to become congenital1 it is evident that some considerable amount of natural or artificial selection of the more favourably varying individuals will still be the only means of securing the race against the constant tendency to degeneration which would ultimately swallow up all the advantages of civilization4 ,the selective influences by which our present high level has been reached and maintained may well be modified1 but they must not be abandoned or reversed in the rash expectation that ,state education1 or ,state feeding of children1 or ,state housing of the poor1 or any amount of ,state socialism or public or private philanthropy1 will prove permanently satisfactory substitutes4 ,if ruinous deterioration and other more immediate evils1 are to be avoided1 the race must still be to the swift and the battle to the strong4 ,the healthy ,individualism so earnestly championed by ,mr4 ,spencer must be allowed free play4 ,open competition1 as ,darwin teaches1 with its survival and multiplication of the fittest1 must be allowed to decide the battle of life independently of a foolish benevolence that prefers the elaborate cultivation and multiplication of weeds to the growth of corn and roses4 ,we are trustees for the countless generations of the future4 ,if we are wise we shall trust to the great ruling truths that we assuredly know1 rather than to the seductive claims of an alleged factor of evolution for which no satisfactory evidence can be produced4 ,,the ,,end4 ,,richard ,,clay ,,and ,,sons1 ,,limited1 ,,london ,,and ,,bungay4 ,,footnotes3 #gb ,professor ,romanes had casts made of the feet of upland geese1 and could not detect any diminution as compared with the web of other geese in relation to the toes4 ,,nature ,,series4 ,,popular ,,lectures ,,and ,,addresses ,,on ,,various ,,subjects ,,in ,,physical ,,science4 ,by ,sir ,,william ,,thomson1 ,d4,c4,l4 ,,ll4,d41 ,f4,r4,s4,e1 ,fellow of ,st4 ,peter's ,college1 ,cambridge1 and ,professor of ,natural ,philosophy in the ,university of ,glasgow4 ,with ,illustrations4 #c vols4 ,crown #hvo4 ,vol4 #a4 ,,constitution ,,of ,,matter4 #fs4 ,,on ,,the ,,origin ,,and ,,metamorphoses ,,of ,,insects4 ,by ,sir ,,john ,,lubbock1 ,bart41 ,f4,r4,s41 ,m4,p41 ,d4,c4,l41 ,,ll4,d4 ,with numerous ,illustrations4 ,third ,edition4 ,crown #hvo4 #cs4 #f;d4 ,,on ,,british ,,wild ,,flowers ,,considered ,,in ,,relation ,,to ,,insects4 ,by ,sir ,,john ,,lubbock1 ,bart41 ,f4,r4,s41 ,m4,p41 ,d4,c4,l41 ,,ll4,d4 ,with ,illustrations4 ,fourth ,edition4 ,crown #hvo4 #ds4 #f;d4 ,,flowers1 ,,fruits ,,and ,,leaves4 ,by ,sir ,,john ,,lubbock1 ,f4,r4,s41 c4 ,second ,edition4 ,crown #hvo4 #ds4 #f;d4 ,,the ,,transit ,,of ,,venus4 ,by ,g4 ,,forbes1 ,m4,a41 ,professor of ,natural ,philosophy in the ,andersonian ,university1 ,glasgow4 ,illustrated4 ,crown #hvo4 #cs4 #f;d4 ,,the ,,common ,,frog4 ,by ,,st4 ,,george ,,mivart1 ,f4,r4,s41 ,lecturer in ,comparative ,anatomy at ,st4 ,mary's ,hospital4 ,with numerous ,illustrations4 ,crown #hvo4 #cs4 #f;d4 ,,polarisation ,,of ,,light4 ,by ,w4 ,,spottiswoode1 ,f4,r4,s4 ,with ,illustrations4 ,fourth ,edition4 ,crown #hvo4 #cs4 #f;d4 ,,the ,,science ,,of ,,weighing ,,and ,,measuring1 ,,and ,,the ,,standards ,,of ,,measure ,,and ,,weight4 ,by ,h4 ,w4 ,,chisholm1 ,warden of the ,standards4 ,with numerous ,illustrations4 ,crown #hvo4 #ds4 #f;d4 ,,how ,,to ,,draw ,a ,,straight ,,line3 a ,lecture on ,linkages4 ,by ,a4 ,b4 ,,kempe4 ,with ,illustrations4 ,crown #hvo4 #as4 #f;d4 ,,light3 ,a ,series of ,simple1 ,entertaining1 and ,inexpensive ,experiments in the ,phenomena of ,light1 for the ,use of ,students of every age4 ,by ,a4 ,m4 ,,mayer and ,c4 ,,barnard4 ,with numerous ,illustrations4 ,crown #hvo4 #bs4 #f;d4 ,,sound3 ,a ,series of ,simple1 ,entertaining1 and ,inexpensive ,experiments in the ,phenomena of ,sound1 for the ,use of ,students of every age4 ,by ,a4 ,m4 ,,mayer1 ,professor of ,physics in the ,stevens ,institute of ,technology1 c4 ,with numerous ,illustrations4 ,crown #hvo4 #cs4 #f;d4 ,,seeing ,,and ,,thinking4 ,by ,professor ,w4 ,k4 ,,clifford1 ,f4,r4,s4 ,with ,diagrams4 ,crown #hvo4 #cs4 #f;d4 ,,degeneration4 ,by ,professor ,e4 ,,ray ,,lankester1 ,f4,r4,s4 ,with ,illustrations4 ,crown #hvo4 #bs4 #f;d4 ,,fashion ,,in ,,deformity1 as ,illustrated in the ,customs of ,barbarous and ,civilized ,races4 ,by ,professor ,,flower4 ,with ,illustrations4 ,crown #hvo4 #bs4 #f;d4 ,,charles ,,darwin4 ,memorial ,notices reprinted from ,nature4 ,by ,,thomas ,,henry ,,huxley1 ,f4,r4,s42 ,g4 ,j4 ,,romanes1 ,f4,r4,s42 ,,archibald ,,geikie1 ,f4,r4,s42 and ,w4 ,t4 ,,thiselton ,,dyer1 ,f4,r4,s4 ,with a ,portrait engraved by ,c4 ,h4 ,,jeens4 ,crown #hvo4 #bs4 #f;d4 ,,on ,,the ,,colours ,,of ,,flowers4 ,as ,illustrated in the ,british ,flora4 ,by ,,grant ,,allen4 ,with ,illustrations4 ,crown #hvo4 #cs4 #f;d4 ,,the ,,scientific ,,evidences ,,of ,,organic ,,evolution4 ,by ,,george ,j4 ,,romanes1 ,m4,a41 ,,ll4,d41 ,f4,r4,s41 ,zoological ,secretary of the ,linnean ,society4 #bs4 #f;d4 ,a ,,century ,,of ,,electricity4 ,by ,t4 ,c4 ,,mendenhall4 ,crown #hvo4 #ds4 #f;d4 ,,the ,,chemistry ,,of ,,the ,,secondary ,,batteries ,,of ,,plante ,,and ,,faure4 ,by ,j4 ,h4 ,,gladstone1 ,ph4,d41 ,f4,r4,s41 and ,,alfred ,,tribe1 ,f4,inst4,c4,e41 ,lecturer on ,chemistry at ,dulwich ,college4 ,crown #hvo4 #bs4 #f;d4 ,,on ,,light4 ,the ,burnett ,lectures4 ,by ,,george ,,gabriel ,,stokes1 ,m4,a41 ,p4,r4,s41 c41 ,fellow of ,pembroke ,college1 and ,lucasian ,professor of ,mathematics in the ,university of ,cambridge4 ,three ,courses3 ,i4 ,on the ,nature of ,light2 ,,ii4 ,on ,light as a ,means of ,investigation2 ,,iii4 ,on the ,beneficial ,effects of ,light4 ,crown #hvo4 #gs4 #f;d4 ,,chemistry ,,of ,,photography4 ,by ,,raphael ,,meldola1 ,f4,r4,s41 ,professor of ,chemistry in the ,finsbury ,technical ,college1 ,city and ,guilds of ,london ,institute for the ,advancement of ,technical ,education4 ,crown #hvo4 #fs4 ,,modern ,,views ,,of ,,electricity4 ,by ,,oliver ,j4 ,,lodge1 ,d4,sc41 ,,ll4,d41 ,f4,r4,s41 ,professor of ,experimental ,physics in ,university ,college1 ,liverpool4 ,with ,illustrations4 ,crown #hvo4 #fs4 #f;d4 ,,timber ,,and ,,some ,,of ,,its ,,diseases4 ,by ,h4 ,,marshall ,,ward1 ,f4,r4,s41 ,fellow of ,christ's ,college1 ,cambridge1 ,professor of ,botany at the ,royal ,indian ,engineering ,college1 ,cooper's ,hill4 ,with ,illustrations4 ,crown #hvo4 #fs4 ,others to follow4 ,,macmillan ,,and ,,co41 ,,london4 99 99 99 99 99 ,,every ,,thursday ,,afternoon1 ,price #f;d4 7,a ,specimen ,number1 post free1 #f-a_/b;d4 stamps47 ,,nature3 ,a ,,weekly ,,illustrated ,,journal ,,of ,,science4 ,,nature contains ,original ,articles on all subjects coming within the domain of ,science1 contributed by the most eminent ,scientists1 belonging to all parts of the world4 ,reviews1 setting forth the nature and value of recent ,scientific works1 are written for ,,nature by men who are acknowledged masters in their particular departments4 ,the ,correspondence columns of ,,nature1 while forming a medium of ,scientific discussion and of intercommunication among the most distinguished men of ,science1 have become the recognized organ for announcing new discoveries and new illustrations of ,scientific principles among observers of ,nature all the world 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