,a ,,history ,,of ,,science ,by ,henry ,smith ,williams1 ,m4,d41 ,,ll4,d4 ,assisted ,by ,edward ,h4 ,williams1 ,m4,d4 ,in ,five ,volumes ,volume ,,iv4 ,,modern ,,development ,,of ,,the ,,chemical ,,and ,,biological ,,sciences ,,book ,,iv4 ,,modern ,,development ,,of ,,the ,,chemical ,,and ,,biological ,,sciences ,,as regards chronology1 the epoch covered in the present volume is identical with that viewed in the preceding one4 ,but now as regards subject matter we pass on to those diverse phases of the physical world which are the field of the chemist1 and to those yet more intricate processes which have to do with living organisms4 ,so radical are the changes here that we seem to be entering new worlds2 and yet1 here as before1 there are intimations of the new discoveries away back in the ,greek days4 ,the solution of the problem of respiration will remind us that ,anaxagoras half guessed the secret2 and in those diversified studies which tell us of the ,daltonian atom in its wonderful transmutations1 we shall be reminded again of the ,clazomenian philosopher and his successor ,democritus4 ,yet we should press the analogy much too far were we to intimate that the ,greek of the elder day or any thinker of a more recent period had penetrated1 even in the vaguest way1 all of the mysteries that the nineteenth century has revealed in the fields of chemistry and biology4 ,at the very most the insight of those great ,greeks and of the wonderful seventeenth-century philosophers who so often seemed on the verge of our later discoveries did no more than vaguely anticipate their successors of this later century4 ,to gain an accurate1 really specific knowledge of the properties of elementary bodies was reserved for the chemists of a recent epoch4 ,the vague ,greek questionings as to organic evolution were world-wide from the precise inductions of a ,darwin4 ,if the mediaeval ,arabian endeavored to dull the knife of the surgeon with the use of drugs1 his results hardly merit to be termed even an anticipation of modern anaesthesia4 ,and when we speak of preventive medicine--of bacteriology in all its phases--we have to do with a marvellous field of which no previous generation of men had even the slightest inkling4 ,all in all1 then1 those that lie before us are perhaps the most wonderful and the most fascinating of all the fields of science4 ,as the chapters of the preceding book carried us out into a macrocosm of inconceivable magnitude1 our present studies are to reveal a microcosm of equally inconceivable smallness4 ,as the studies of the physicist attempted to reveal the very nature of matter and of energy1 we have now to seek the solution of the yet more inscrutable problems of life and of mind4 ,i4 ,,the ,,phlogiston ,,theory ,,in ,,chemistry ,the development of the science of chemistry from the science of alchemy is a striking example of the complete revolution in the attitude of observers in the field of science4 ,as has been pointed out in a preceding chapter1 the alchemist1 having a preconceived idea of how things should be1 made all his experiments to prove his preconceived theory2 while the chemist reverses this attitude of mind and bases his conceptions on the results of his laboratory experiments4 ,in short1 chemistry is what alchemy never could be1 an inductive science4 ,but this transition from one point of view to an exactly opposite one was necessarily a very slow process4 ,ideas that have held undisputed sway over the minds of succeeding generations for hundreds of years cannot be overthrown in a moment1 unless the agent of such an overthrow be so obvious that it cannot be challenged4 ,the rudimentary chemistry that overthrew alchemy had nothing so obvious and palpable4 ,the great first step was the substitution of the one principle1 phlogiston1 for the three principles1 salt1 sulphur1 and mercury4 ,we have seen how the experiment of burning or calcining such a metal as lead destroyed the lead as such1 leaving an entirely different substance in its place1 and how the original metal could be restored by the addition of wheat to the calcined product4 ,to the alchemist this was mortification and revivification of the metal4 ,for1 as pointed out by ,paracelsus1 anything that could be killed by man could also be revivified by him1 although this was not possible to the things killed by ,god4 ,the burning of such substances as wood1 wax1 oil1 etc41 was also looked upon as the same killing process1 and the fact that the alchemist was unable to revivify them was regarded as simply the lack of skill on his part1 and in no wise affecting the theory itself4 ,but the iconoclastic spirit1 if not the acceptance of all the teachings1 of the great ,paracelsus had been gradually taking root among the better class of alchemists1 and about the middle of the seventeenth century ,robert ,boyle 7#afbf-afia7 called attention to the possibility of making a wrong deduction from the phenomenon of the calcination of the metals1 because of a very important factor1 the action of the air1 which was generally overlooked4 ,and he urged his colleagues of the laboratories to give greater heed to certain other phenomena that might pass unnoticed in the ordinary calcinating process4 ,in his work1 ,the ,sceptical ,chemist1 he showed the reasons for doubting the threefold constitution of matter2 and in his ,general ,history of the ,air advanced some novel and carefully studied theories as to the composition of the atmosphere4 ,this was an important step1 and although ,boyle is not directly responsible for the phlogiston theory1 it is probable that his experiments on the atmosphere influenced considerably the real founders1 ,becker and ,stahl4 ,boyle gave very definitely his idea of how he thought air might be composed4 ,i conjecture that the atmospherical air consists of three different kinds of corpuscles1 he says2 the first1 those numberless particles which1 in the form of vapors or dry exhalations1 ascend from the earth1 water1 minerals1 vegetables1 animals1 etc42 in a word1 whatever substances are elevated by the celestial or subterraneal heat1 and thence diffused into the atmosphere4 ,the second may be yet more subtle1 and consist of those exceedingly minute atoms1 the magnetical effluvia of the earth1 with other innumerable particles sent out from the bodies of the celestial luminaries1 and causing1 by their influence1 the idea of light in us4 ,the third sort is its characteristic and essential property1 ,i mean permanently elastic parts4 ,various hypotheses may be framed relating to the structure of these later particles of the air4 ,they might be resembled to the springs of watches1 coiled up and endeavoring to restore themselves2 to wool1 which1 being compressed1 has an elastic force2 to slender wires of different substances1 consistencies1 lengths1 and thickness2 in greater curls or less1 near to1 or remote from each other1 etc41 yet all continuing springy1 expansible1 and compressible4 ,lastly1 they may also be compared to the thin shavings of different kinds of wood1 various in their lengths1 breadth1 and thickness4 ,and this1 perhaps1 will seem the most eligible hypothesis1 because it1 in some measure1 illustrates the production of the elastic particles we are considering4 ,for no art or curious instruments are required to make these shavings whose curls are in no wise uniform1 but seemingly casual2 and what is more remarkable1 bodies that before seemed unelastic1 as beams and blocks1 will afford them47#a7 ,although this explanation of the composition of the air is most crude1 it had the effect of directing attention to the fact that the atmosphere is not mere nothingness1 but a something with a definite composition1 and this served as a good foundation for future investigations4 ,to be sure1 ,boyle was neither the first nor the only chemist who had suspected that the air was a mixture of gases1 and not a simple one1 and that only certain of these gases take part in the process of calcination4 ,jean ,rey1 a ,french physician1 and ,john ,mayow1 an ,englishman1 had preformed experiments which showed conclusively that the air was not a simple substance2 but ,boyle's work was better known1 and in its effect probably more important4 ,but with all ,boyle's explanations of the composition of air1 he still believed that there was an inexplicable something1 a vital substance1 which he was unable to fathom1 and which later became the basis of ,stahl's phlogiston theory4 ,commenting on this mysterious substance1 ,boyle says3 ,the difficulty we find in keeping flame and fire alive1 though but for a little time1 without air1 renders it suspicious that there be dispersed through the rest of the atmosphere some odd substance1 either of a solar1 astral1 or other foreign nature2 on account of which the air is so necessary to the substance of flame6 ,it was this idea that attracted the attention of ,george ,ernst ,stahl 7#affj-agcd71 a professor of medicine in the ,university of ,halle1 who later founded his new theory upon it4 ,stahl's theory was a development of an earlier chemist1 ,johann ,joachim ,becker 7#afce-afhb71 in whose footsteps he followed and whose experiments he carried further4 ,in many experiments ,stahl had been struck with the fact that certain substances1 while differing widely1 from one another in many respects1 were alike in combustibility4 ,from this he argued that all combustible substances must contain a common principle1 and this principle he named phlogiston4 ,this phlogiston he believed to be intimately associated in combination with other substances in nature1 and in that condition not perceivable by the senses2 but it was supposed to escape as a substance burned1 and become apparent to the senses as fire or flame4 ,in other words1 phlogiston was something imprisoned in a combustible structure 7itself forming part of the structure71 and only liberated when this structure was destroyed4 ,fire1 or flame1 was ,,free phlogiston1 while the imprisoned phlogiston was called ,,combined ,,phlogiston1 or combined fire4 ,the peculiar quality of this strange substance was that it disliked freedom and was always striving to conceal itself in some combustible substance4 ,boyle's tentative suggestion that heat was simply motion was apparently not accepted by ,stahl1 or perhaps it was unknown to him4 ,according to the phlogistic theory1 the part remaining after a substance was burned was simply the original substance deprived of phlogiston4 ,to restore the original combustible substance1 it was necessary to heat the residue of the combustion with something that burned easily1 so that the freed phlogiston might again combine with the ashes4 ,this was explained by the supposition that the more combustible a substance was the more phlogiston it contained1 and since free phlogiston sought always to combine with some suitable substance1 it was only necessary to mix the phlogisticating agents1 such as charcoal1 phosphorus1 oils1 fats1 etc41 with the ashes of the original substance1 and heat the mixture1 the phlogiston thus freed uniting at once with the ashes4 ,this theory fitted very nicely as applied to the calcined lead revivified by the grains of wheat1 although with some other products of calcination it did not seem to apply at all4 ,it will be seen from this that the phlogistic theory was a step towards chemistry and away from alchemy4 ,it led away from the idea of a spirit in metals that could not be seen1 felt1 or appreciated by any of the senses1 and substituted for it a principle which1 although a falsely conceived one1 was still much more tangible than the spirit1 since it could be seen and felt as free phlogiston and weighed and measured as combined phlogiston4 ,the definiteness of the statement that a metal1 for example1 was composed of phlogiston and an element was much less enigmatic1 even if wrong1 than the statement of the alchemist that metals are produced by the spiritual action of the three principles1 salt1 mercury1 sulphur--particularly when it is explained that salt1 mercury1 and sulphur were really not what their names implied1 and that there was no universally accepted belief as to what they really were4 ,the metals1 which are now regarded as elementary bodies1 were considered compounds by the phlogistians1 and they believed that the calcining of a metal was a process of simplification4 ,they noted1 however1 that the remains of calcination weighed more than the original product1 and the natural inference from this would be that the metal must have taken in some substance rather than have given off anything4 ,but the phlogistians had not learned the all-important significance of weights1 and their explanation of variation in weight was either that such gain or loss was an unimportant accident at best1 or that phlogiston1 being light1 tended to lighten any substance containing it1 so that driving it out of the metal by calcination naturally left the residue heavier4 ,at first the phlogiston theory seemed to explain in an indisputable way all the known chemical phenomena4 ,gradually1 however1 as experiments multiplied1 it became evident that the plain theory as stated by ,stahl and his followers failed to explain satisfactorily certain laboratory reactions4 ,to meet these new conditions1 certain modifications were introduced from time to time1 giving the theory a flexibility that would allow it to cover all cases4 ,but as the number of inexplicable experiments continued to increase1 and new modifications to the theory became necessary1 it was found that some of these modifications were directly contradictory to others1 and thus the simple theory became too cumbersome from the number of its modifications4 ,its supporters disagreed among themselves1 first as to the explanation of certain phenomena that did not seem to accord with the phlogistic theory1 and a little later as to the theory itself4 ,but as yet there was no satisfactory substitute for this theory1 which1 even if unsatisfactory1 seemed better than anything that had gone before or could be suggested4 ,but the good effects of the era of experimental research1 to which the theory of ,stahl had given such an impetus1 were showing in the attitude of the experimenters4 ,the works of some of the older writers1 such as ,boyle and ,hooke1 were again sought out in their dusty corners and consulted1 and their surmises as to the possible mixture of various gases in the air were more carefully considered4 ,still the phlogiston theory was firmly grounded in the minds of the philosophers1 who can hardly be censured for adhering to it1 at least until some satisfactory substitute was offered4 ,the foundation for such a theory was finally laid1 as we shall see presently1 by the work of ,black1 ,priestley1 ,cavendish1 and ,lavoisier1 in the eighteenth century1 but the phlogiston theory cannot be said to have finally succumbed until the opening years of the nineteenth century4 ,,ii4 ,,the ,,beginnings ,,of ,,modern ,,chemistry ,,the ,,pneumatic ,,chemists ,modern chemistry may be said to have its beginning with the work of ,stephen ,hales 7#afgg-agfa71 who early in the eighteenth century began his important study of the elasticity of air4 ,departing from the point of view of most of the scientists of the time1 he considered air to be a fine elastic fluid1 with particles of very different nature floating in it2 and he showed that these particles could be separated4 ,he pointed out1 also1 that various gases1 or airs1 as he called them1 were contained in many solid substances4 ,the importance of his work1 however1 lies in the fact that his general studies were along lines leading away from the accepted doctrines of the time1 and that they gave the impetus to the investigation of the properties of gases by such chemists as ,black1 ,priestley1 ,cavendish1 and ,lavoisier1 whose specific discoveries are the foundation-stones of modern chemistry4 ,,joseph ,,black ,the careful studies of ,hales were continued by his younger confrere1 ,dr4 ,joseph ,black 7#agbh-agii71 whose experiments in the weights of gases and other chemicals were first steps in quantitative chemistry4 ,but even more important than his discoveries of chemical properties in general was his discovery of the properties of carbonic-acid gas4 ,black had been educated for the medical profession in the ,university of ,glasgow1 being a friend and pupil of the famous ,dr4 ,william ,cullen4 ,but his liking was for the chemical laboratory rather than for the practice of medicine4 ,within three years after completing his medical course1 and when only twenty-three years of age1 he made the discovery of the properties of carbonic acid1 which he called by the name of fixed air4 ,after discovering this gas1 ,black made a long series of experiments1 by which he was able to show how widely it was distributed throughout nature4 ,thus1 in #ageg1 he discovered that the bubbles given off in the process of brewing1 where there was vegetable fermentation1 were composed of it4 ,to prove this1 he collected the contents of these bubbles in a bottle containing lime-water4 ,when this bottle was shaken violently1 so that the lime-water and the carbonic acid became thoroughly mixed1 an insoluble white powder was precipitated from the solution1 the carbonic acid having combined chemically with the lime to form the insoluble calcium carbonate1 or chalk4 ,this experiment suggested another4 ,fixing a piece of burning charcoal in the end of a bellows1 he arranged a tube so that the gas coming from the charcoal would pass through the lime-water1 and1 as in the case of the bubbles from the brewer's vat1 he found that the white precipitate was thrown down2 in short1 that carbonic acid was given off in combustion4 ,shortly after1 ,black discovered that by blowing through a glass tube inserted into lime-water1 chalk was precipitated1 thus proving that carbonic acid was being constantly thrown off in respiration4 ,the effect of ,black's discoveries was revolutionary1 and the attitude of mind of the chemists towards gases1 or airs1 was changed from that time forward4 ,most of the chemists1 however1 attempted to harmonize the new facts with the older theories--to explain all the phenomena on the basis of the phlogiston theory1 which was still dominant4 ,but while many of ,black's discoveries could not be made to harmonize with that theory1 they did not directly overthrow it4 ,it required the additional discoveries of some of ,black's fellow-scientists to complete its downfall1 as we shall see4 ,,henry ,,cavendish ,this work of ,black's was followed by the equally important work of his former pupil1 ,henry ,cavendish 7#agca-ahaj71 whose discovery of the composition of many substances1 notably of nitric acid and of water1 was of great importance1 adding another link to the important chain of evidence against the phlogiston theory4 ,cavendish is one of the most eccentric figures in the history of science1 being widely known in his own time for his immense wealth and brilliant intellect1 and also for his peculiarities and his morbid sensibility1 which made him dread society1 and probably did much in determining his career4 ,fortunately for him1 and incidentally for the cause of science1 he was able to pursue laboratory investigations without being obliged to mingle with his dreaded fellow-mortals1 his every want being provided for by the immense fortune inherited from his father and an uncle4 ,when a young man1 as a pupil of ,dr4 ,black1 he had become imbued with the enthusiasm of his teacher1 continuing ,black's investigations as to the properties of carbonic-acid gas when free and in combination4 ,one of his first investigations was reported in #agff1 when he communicated to the ,royal ,society his experiments for ascertaining the properties of carbonic-acid and hydrogen gas1 in which he first showed the possibility of weighing permanently elastic fluids1 although ,torricelli had before this shown the relative weights of a column of air and a column of mercury4 ,other important experiments were continued by ,cavendish1 and in #aghd he announced his discovery of the composition of water1 thus robbing it of its time-honored position as an element4 ,but his claim to priority in this discovery was at once disputed by his fellow-countryman ,james ,watt and by the ,frenchman ,lavoisier4 ,lavoisier's claim was soon disallowed even by his own countrymen1 but for many years a bitter controversy was carried on by the partisans of ,watt and ,cavendish4 ,the two principals1 however1 seem never to have entered into this controversy with anything like the same ardor as some of their successors1 as they remained on the best of terms47#a7 ,it is certain1 at any rate1 that ,cavendish announced his discovery officially before ,watt claimed that the announcement had been previously made by him1 and1 whether right or wrong1 the honor of scientific discoveries seems to be accorded naturally to the man who first publishes a demonstration of his discovery4 ,englishmen very generally admit the justness of ,cavendish's claim1 although the ,french scientist ,arago1 after reviewing the evidence carefully in #ahcc1 decided in favor of ,watt4 ,it appears that something like a year before ,cavendish made known his complete demonstration of the composition of water1 ,watt communicated to the ,royal ,society a suggestion that water was composed of dephlogisticated air 7oxygen7 and phlogiston 7hydrogen7 deprived of part of its latent heat4 ,cavendish knew of the suggestion1 but in his experiments refuted the idea that the hydrogen lost any of its latent heat4 ,furthermore1 ,watt merely suggested the possible composition without proving it1 although his idea was practically correct1 if we can rightly interpret the vagaries of the nomenclature then in use4 ,but had ,watt taken the steps to demonstrate his theory1 the great ,water ,controversy would have been avoided4 ,cavendish's report of his discovery to the ,royal ,society covers something like forty pages of printed matter4 ,in this he shows how1 by passing an electric spark through a closed jar containing a mixture of hydrogen gas and oxygen1 water is invariably formed1 apparently by the union of the two gases4 ,the experiment was first tried with hydrogen and common air1 the oxygen of the air uniting with the hydrogen to form water1 leaving the nitrogen of the air still to be accounted for4 ,with pure oxygen and hydrogen1 however1 ,cavendish found that pure water was formed1 leaving slight traces of any other1 substance which might not be interpreted as being ,chemical impurities4 ,there was only one possible explanation of this phenomenon--that hydrogen and oxygen1 when combined1 form water4 ,by experiments with the globe it appeared1 wrote ,cavendish1 that when inflammable and common air are exploded in a proper proportion1 almost all the inflammable air1 and near one-fifth the common air1 lose their elasticity and are condensed into dew4 ,and by this experiment it appears that this dew is plain water1 and consequently that almost all the inflammable air is turned into pure water4 ,in order to examine the nature of the matter condensed on firing a mixture of dephlogisticated and inflammable air1 ,i took a glass globe1 holding #hhjj grain measures1 furnished with a brass cock and an apparatus for firing by electricity4 ,this globe was well exhausted by an air-pump1 and then filled with a mixture of inflammable and dephlogisticated air by shutting the cock1 fastening the bent glass tube into its mouth1 and letting up the end of it into a glass jar inverted into water and containing a mixture of #ai1ejj grain measures of dephlogisticated air1 and #cg1jjj of inflammable air2 so that1 upon opening the cock1 some of this mixed air rushed through the bent tube and filled the globe4 ,the cock was then shut and the included air fired by electricity1 by means of which almost all of it lost its elasticity 7was condensed into water vapors74 ,the cock was then again opened so as to let in more of the same air to supply the place of that destroyed by the explosion1 which was again fired1 and the operation continued till almost the whole of the mixture was let into the globe and exploded4 ,by this means1 though the globe held not more than a sixth part of the mixture1 almost the whole of it was exploded therein without any fresh exhaustion of the globe4 ,at first this condensed matter was acid to the taste and contained two grains of nitre1 but ,cavendish1 suspecting that this was due to impurities1 tried another experiment that proved conclusively that his opinions were correct4 ,i therefore made another experiment1 he says1 with some more of the same air from plants in which the proportion of inflammable air was greater1 so that the burnt air was almost completely phlogisticated1 its standard being one-tenth4 ,the condensed liquor was then not at all acid1 but seemed pure water4 ,from these experiments he concludes that when a mixture of inflammable and dephlogisticated air is exploded1 in such proportions that the burnt air is not much phlogisticated1 the condensed liquor contains a little acid which is always of the nitrous kind1 whatever substance the dephlogisticated air is procured from2 but if the proportion be such that the burnt air is almost entirely phlogisticated1 the condensed liquor is not at all acid1 but seems pure water1 without any addition whatever47#b7 ,these same experiments1 which were undertaken to discover the composition of water1 led him to discover also the composition of nitric acid4 ,he had observed that1 in the combustion of hydrogen gas with common air1 the water was slightly tinged with acid1 but that this was not the case when pure oxygen gas was used4 ,acting upon this observation1 he devised an experiment to determine the nature of this acid4 ,he constructed an apparatus whereby an electric spark was passed through a vessel containing common air4 ,after this process had been carried on for several weeks a small amount of liquid was formed4 ,this liquid combined with a solution of potash to form common nitre1 which detonated with charcoal1 sparkled when paper impregnated with it was burned1 and gave out nitrous fumes when sulphuric acid was poured on it4 ,in other words1 the liquid was shown to be nitric acid4 ,now1 since nothing but pure air had been used in the initial experiment1 and since air is composed of nitrogen and oxygen1 there seemed no room to doubt that nitric acid is a combination of nitrogen and oxygen4 ,this discovery of the nature of nitric acid seems to have been about the last work of importance that ,cavendish did in the field of chemistry1 although almost to the hour of his death he was constantly occupied with scientific observations4 ,even in the last moments of his life this habit asserted itself1 according to ,lord ,brougham4 ,he died on ,march #aj1 #ahaj1 after a short illness1 probably the first1 as well as the last1 which he ever suffered4 ,his habit of curious observation continued to the end4 ,he was desirous of marking the progress of the disease and the gradual extinction of the vital powers4 ,with these ends in view1 that he might not be disturbed1 he desired to be left alone4 ,his servant1 returning sooner than he had wished1 was ordered again to leave the chamber of death1 and when he came back a second time he found his master had expired47#c7 ,,joseph ,,priestley ,while the opulent but diffident ,cavendish was making his important discoveries1 another ,englishman1 a poor country preacher named ,joseph ,priestley 7#agcc-ahjd7 was not only rivalling him1 but1 if anything1 outstripping him in the pursuit of chemical discoveries4 ,in #agfa this young minister was given a position as tutor in a nonconformist academy at ,warrington1 and here1 for six years1 he was able to pursue his studies in chemistry and electricity4 ,in #agff1 while on a visit to ,london1 he met ,benjamin ,franklin1 at whose suggestion he published his ,history of ,electricity4 ,from this time on he made steady progress in scientific investigations1 keeping up his ecclesiastical duties at the same time4 ,in #aghj he removed to ,birmingham1 having there for associates such scientists as ,james ,watt1 ,boulton1 and ,erasmus ,darwin4 ,eleven years later1 on the anniversary of the fall of the ,bastile in ,paris1 a fanatical mob1 knowing ,priestley's sympathies with the ,french revolutionists1 attacked his house and chapel1 burning both and destroying a great number of valuable papers and scientific instruments4 ,priestley and his family escaped violence by flight1 but his most cherished possessions were destroyed2 and three years later he quitted ,england forever1 removing to the ,united ,states1 whose struggle for liberty he had championed4 ,the last ten years of his life were spent at ,northumberland1 ,pennsylvania1 where he continued his scientific researches4 ,early in his scientific career ,priestley began investigations upon the fixed air of ,dr4 ,black1 and1 oddly enough1 he was stimulated to this by the same thing that had influenced ,black--that is1 his residence in the immediate neighborhood of a brewery4 ,it was during the course of a series of experiments on this and other gases that he made his greatest discovery1 that of oxygen1 or dephlogisticated air1 as he called it4 ,the story of this important discovery is probably best told in ,priestley's own words3 ,there are1 ,i believe1 very few maxims in philosophy that have laid firmer hold upon the mind than that air1 meaning atmospheric air1 is a simple elementary substance1 indestructible and unalterable1 at least as much so as water is supposed to be4 ,in the course of my inquiries ,i was1 however1 soon satisfied that atmospheric air is not an unalterable thing2 for that1 according to my first hypothesis1 the phlogiston with which it becomes loaded from bodies burning in it1 and the animals breathing it1 and various other chemical processes1 so far alters and depraves it as to render it altogether unfit for inflammation1 respiration1 and other purposes to which it is subservient2 and ,i had discovered that agitation in the water1 the process of vegetation1 and probably other natural processes1 restore it to its original purity4444 ,having procured a lens of twelve inches diameter and twenty inches local distance1 ,i proceeded with the greatest alacrity1 by the help of it1 to discover what kind of air a great variety of substances would yield1 putting them into the vessel1 which ,i filled with quicksilver1 and kept inverted in a basin of the same 4444 ,with this apparatus1 after a variety of experiments4444 on the #ast of ,august1 #aggd1 ,i endeavored to extract air from mercurius calcinatus per se2 and ,i presently found that1 by means of this lens1 air was expelled from it very readily4 ,having got about three or four times as much as the bulk of my materials1 ,i admitted water to it1 and found that it was not imbibed by it4 ,but what surprised me more than ,i can express was that a candle burned in this air with a remarkably vigorous flame1 very much like that enlarged flame with which a candle burns in nitrous oxide1 exposed to iron or liver of sulphur2 but as ,i had got nothing like this remarkable appearance from any kind of air besides this particular modification of vitrous air1 and ,i knew no vitrous acid was used in the preparation of mercurius calcinatus1 ,i was utterly at a loss to account for it47#d7 ,the new air was1 of course1 oxygen4 ,priestley at once proceeded to examine it by a long series of careful experiments1 in which1 as will be seen1 he discovered most of the remarkable qualities of this gas4 ,continuing his description of these experiments1 he says3 ,the flame of the candle1 besides being larger1 burned with more splendor and heat than in that species of nitrous air2 and a piece of red-hot wood sparkled in it1 exactly like paper dipped in a solution of nitre1 and it consumed very fast2 an experiment that ,i had never thought of trying with dephlogisticated nitrous air4 444 ,i had so little suspicion of the air from the mercurius calcinatus1 etc41 being wholesome1 that ,i had not even thought of applying it to the test of nitrous air2 but thinking 7as my reader must imagine ,i frequently must have done7 on the candle burning in it after long agitation in water1 it occurred to me at last to make the experiment2 and1 putting one measure of nitrous air to two measures of this air1 ,i found not only that it was diminished1 but that it was diminished quite as much as common air1 and that the redness of the mixture was likewise equal to a similar mixture of nitrous and common air4444 ,the next day ,i was more surprised than ever ,i had been before with finding that1 after the above-mentioned mixture of nitrous air and the air from mercurius calcinatus had stood all night1444 a candle burned in it1 even better than in common air4 ,a little later ,priestley discovered that dephlogisticated air444 is a principal element in the composition of acids1 and may be extracted by means of heat from many substances which contain them4444 ,it is likewise produced by the action of light upon green vegetables2 and this seems to be the chief means employed to preserve the purity of the atmosphere4 ,this recognition of the important part played by oxygen in the atmosphere led ,priestley to make some experiments upon mice and insects1 and finally upon himself1 by inhalations of the pure gas4 ,the feeling in my lungs1 he said1 was not sensibly different from that of common air1 but ,i fancied that my breathing felt peculiarly light and easy for some time afterwards4 ,who can tell but that in time this pure air may become a fashionable article in luxury8444 ,perhaps we may from these experiments see that though pure dephlogisticated air might be useful as a medicine1 it might not be so proper for us in the usual healthy state of the body4 ,this suggestion as to the possible usefulness of oxygen as a medicine was prophetic4 ,a century later the use of oxygen had become a matter of routine practice with many physicians4 ,even in ,priestley's own time such men as ,dr4 ,john ,hunter expressed their belief in its efficacy in certain conditions1 as we shall see1 but its value in medicine was not fully appreciated until several generations later4 ,several years after discovering oxygen ,priestley thus summarized its properties3 ,it is this ingredient in the atmospheric air that enables it to support combustion and animal life4 ,by means of it most intense heat may be produced1 and in the purest of it animals will live nearly five times as long as in an equal quantity of atmospheric air4 ,in respiration1 part of this air1 passing the membranes of the lungs1 unites with the blood and imparts to it its florid color1 while the remainder1 uniting with phlogiston exhaled from venous blood1 forms mixed air4 ,it is dephlogisticated air combined with water that enables fishes to live in it47#e7 ,,karl ,,wilhelm ,,scheele ,the discovery of oxygen was the last but most important blow to the tottering phlogiston theory1 though ,priestley himself would not admit it4 ,but before considering the final steps in the overthrow of ,stahl's famous theory and the establishment of modern chemistry1 we must review the work of another great chemist1 ,karl ,wilhelm ,scheele 7#agdb-aghf71 of ,sweden1 who discovered oxygen quite independently1 although later than ,priestley4 ,in the matter of brilliant discoveries in a brief space of time ,scheele probably eclipsed all his great contemporaries4 ,he had a veritable genius for interpreting chemical reactions and discovering new substances1 in this respect rivalling ,priestley himself4 ,unlike ,priestley1 however1 he planned all his experiments along the lines of definite theories from the beginning1 the results obtained being the logical outcome of a predetermined plan4 ,scheele was the son of a merchant of ,stralsund1 ,pomerania1 which then belonged to ,sweden4 ,as a boy in school he showed so little aptitude for the study of languages that he was apprenticed to an apothecary at the age of fourteen4 ,in this work he became at once greatly interested1 and1 when not attending to his duties in the dispensary1 he was busy day and night making experiments or studying books on chemistry4 ,in #agge1 still employed as an apothecary1 he moved to ,stockholm1 and soon after he sent to ,bergman1 the leading chemist of ,sweden1 his first discovery--that of tartaric acid1 which he had isolated from cream of tartar4 ,this was the beginning of his career of discovery1 and from that time on until his death he sent forth accounts of new discoveries almost uninterruptedly4 ,meanwhile he was performing the duties of an ordinary apothecary1 and struggling against poverty4 ,his treatise upon ,air and ,fire appeared in #aggg4 ,in this remarkable book he tells of his discovery of oxygen--empyreal or fire-air1 as he calls it--which he seems to have made independently and without ever having heard of the previous discovery by ,priestley4 ,in this book1 also1 he shows that air is composed chiefly of oxygen and nitrogen gas4 ,early in his experimental career ,scheele undertook the solution of the composition of black oxide of manganese1 a substance that had long puzzled the chemists4 ,he not only succeeded in this1 but incidentally in the course of this series of experiments he discovered oxygen1 baryta1 and chlorine1 the last of far greater importance1 at least commercially1 than the real object of his search4 ,in speaking of the experiment in which the discovery was made he says3 ,when marine 7hydrochloric7 acid stood over manganese in the cold it acquired a dark reddish-brown color4 ,as manganese does not give any colorless solution without uniting with phlogiston 7probably meaning hydrogen71 it follows that marine acid can dissolve it without this principle4 ,but such a solution has a blue or red color4 ,the color is here more brown than red1 the reason being that the very finest portions of the manganese1 which do not sink so easily1 swim in the red solution2 for without these fine particles the solution is red1 and red mixed with black is brown4 ,the manganese has here attached itself so loosely to acidum salis that the water can precipitate it1 and this precipitate behaves like ordinary manganese4 ,when1 now1 the mixture of manganese and spiritus salis was set to digest1 there arose an effervescence and smell of aqua regis47#f7 ,the effervescence he refers to was chlorine1 which he proceeded to confine in a suitable vessel and examine more fully4 ,he described it as having a quite characteristically suffocating smell1 which was very offensive4 ,he very soon noted the decolorizing or bleaching effects of this now product1 finding that it decolorized flowers1 vegetables1 and many other substances4 ,commercially this discovery of chlorine was of enormous importance and the practical application of this new chemical in bleaching cloth soon supplanted the old process of crofting--that is1 bleaching by spreading the cloth upon the grass4 ,but although ,scheele first pointed out the bleaching quality of his newly discovered gas1 it was the ,french savant1 ,berthollet1 who1 acting upon ,scheele's discovery that the new gas would decolorize vegetables and flowers1 was led to suspect that this property might be turned to account in destroying the color of cloth4 ,in #aghe he read a paper before the ,academy of ,sciences of ,paris1 in which he showed that bleaching by chlorine was entirely satisfactory1 the color but not the substance of the cloth being affected4 ,he had experimented previously and found that the chlorine gas was soluble in water and could thus be made practically available for bleaching purposes4 ,in #aghf ,james ,watt examined specimens of the bleached cloth made by ,berthollet1 and upon his return to ,england first instituted the process of practical bleaching4 ,his process1 however1 was not entirely satisfactory1 and1 after undergoing various modifications and improvements1 it was finally made thoroughly practicable by ,mr4 ,tennant1 who hit upon a compound of chlorine and lime--the chloride of lime--which was a comparatively cheap chemical product1 and answered the purpose better even than chlorine itself4 ,to appreciate how momentous this discovery was to cloth manufacturers1 it should be remembered that the old process of bleaching consumed an entire summer for the whitening of a single piece of linen2 the new process reduced the period to a few hours4 ,to be sure1 lime had been used with fair success previous to ,tennant's discovery1 but successful and practical bleaching by a solution of chloride of lime was first made possible by him and through ,scheele's discovery of chlorine4 ,until the time of ,scheele the great subject of organic chemistry had remained practically unexplored1 but under the touch of his marvellous inventive genius new methods of isolating and studying animal and vegetable products were introduced1 and a large number of acids and other organic compounds prepared that had been hitherto unknown4 ,his explanations of chemical phenomena were based on the phlogiston theory1 in which1 like ,priestley1 he always1 believed4 ,although in error in this respect1 he was1 nevertheless1 able to make his discoveries with extremely accurate interpretations4 ,a brief epitome of the list of some of his more important discoveries conveys some idea1 of his fertility of mind as well as his industry4 ,in #aghj he discovered lactic acid17#g7 and showed that it was the substance that caused the acidity of sour milk2 and in the same year he discovered mucic acid4 ,next followed the discovery of tungstic acid1 and in #aghc he added to his list of useful discoveries that of glycerine4 ,then in rapid succession came his announcements of the new vegetable products citric1 malic1 oxalic1 and gallic acids4 ,scheele not only made the discoveries1 but told the world how he had made them--how any chemist might have made them if he chose--for he never considered that he had really discovered any substance until he had made it1 decomposed it1 and made it again4 ,his experiments on ,prussian blue are most interesting1 not only because of the enormous amount of work involved and the skill he displayed in his experiments1 but because all the time the chemist was handling1 smelling1 and even tasting a compound of one of the most deadly poisons1 ignorant of the fact that the substance was a dangerous one to handle4 ,his escape from injury seems almost miraculous2 for his experiments1 which were most elaborate1 extended over a considerable period of time1 during which he seems to have handled this chemical with impunity4 ,while only forty years of age and just at the zenith of his fame1 ,scheele was stricken by a fatal illness1 probably induced by his ceaseless labor and exposure4 ,it is gratifying to know1 however1 that during the last eight or nine years of his life he had been less bound down by pecuniary difficulties than before1 as ,bergman had obtained for him an annual grant from the ,academy4 ,but it was characteristic of the man that1 while devoting one-sixth of the amount of this grant to his personal wants1 the remaining five-sixths was devoted to the expense of his experiments4 ,,lavoisier ,,and ,,the ,,foundation ,,of ,,modern ,,chemistry ,the time was ripe for formulating the correct theory of chemical composition3 it needed but the master hand to mould the materials into the proper shape4 ,the discoveries in chemistry during the eighteenth century had been far-reaching and revolutionary in character4 ,a brief review of these discoveries shows how completely they had subverted the old ideas of chemical elements and chemical compounds4 ,of the four substances earth1 air1 fire1 and water1 for many centuries believed to be elementary bodies1 not one has stood the test of the eighteenth-century chemists4 ,earth had long since ceased to be regarded as an element1 and water and air had suffered the same fate in this century4 ,and now at last fire itself1 the last of the four elements and the keystone to the phlogiston arch1 was shown to be nothing more than one of the manifestations of the new element1 oxygen1 and not phlogiston or any other intangible substance4 ,in this epoch of chemical discoveries ,england had produced such mental giants and pioneers in science as ,black1 ,priestley1 and ,cavendish2 ,sweden had given the world ,scheele and ,bergman1 whose work1 added to that of their ,english confreres1 had laid the broad base of chemistry as a science2 but it was for ,france to produce a man who gave the final touches to the broad but rough workmanship of its foundation1 and establish it as the science of modern chemistry4 ,it was for ,antoine ,laurent ,lavoisier 7#agdc-agid7 to gather together1 interpret correctly1 rename1 and classify the wealth of facts that his immediate predecessors and contemporaries had given to the world4 ,the attitude of the mother-countries towards these illustrious sons is an interesting piece of history4 ,sweden honored and rewarded ,scheele and ,bergman for their efforts2 ,england received the intellectuality of ,cavendish with less appreciation than the ,continent1 and a fanatical mob drove ,priestley out of the country2 while ,france1 by sending ,lavoisier to the guillotine1 demonstrated how dangerous it was1 at that time at least1 for an intelligent ,frenchman to serve his fellowman and his country well4 ,the revolution brought about by ,lavoisier in science1 says ,hoefer1 coincides by a singular act of destiny with another revolution1 much greater indeed1 going on then in the political and social world4 ,both happened on the same soil1 at the same epoch1 among the same people2 and both marked the commencement of a new era in their respective spheres47#h7 ,lavoisier was born in ,paris1 and being the son of an opulent family1 was educated under the instruction of the best teachers of the day4 ,with ,lacaille he studied mathematics and astronomy2 with ,jussieu1 botany2 and1 finally1 chemistry under ,rouelle4 ,his first work of importance was a paper on the practical illumination of the streets of ,paris1 for which a prize had been offered by ,m4 de ,sartine1 the chief of police4 ,this prize was not awarded to ,lavoisier1 but his suggestions were of such importance that the king directed that a gold medal be bestowed upon the young author at the public sitting of the ,academy in ,april1 #aggf4 ,two years later1 at the age of thirty-five1 ,lavoisier was admitted a member of the ,academy4 ,in this same year he began to devote himself almost exclusively to chemical inquiries1 and established a laboratory in his home1 fitted with all manner of costly apparatus and chemicals4 ,here he was in constant communication with the great men of science of ,paris1 to all of whom his doors were thrown open4 ,one of his first undertakings in this laboratory was to demonstrate that water could not be converted into earth by repeated distillations1 as was generally advocated2 and to show also that there was no foundation to the existing belief that it was possible to convert water into a gas so elastic as to pass through the pores of a vessel4 ,he demonstrated the fallaciousness of both these theories in #agfh-agfi by elaborate experiments1 a single investigation of this series occupying one hundred and one days4 ,in #agga he gave the first blow to the phlogiston theory by his experiments on the calcination of metals4 ,it will be recalled that one basis for the belief in phlogiston was the fact that when a metal was calcined it was converted into an ash1 giving up its phlogiston in the process4 ,to restore the metal1 it was necessary to add some substance such as wheat or charcoal to the ash4 ,lavoisier1 in examining this process of restoration1 found that there was always evolved a great quantity of air1 which he supposed to be fixed air or carbonic acid--the same that escapes in effervescence of alkalies and calcareous earths1 and in the fermentation of liquors4 ,he then examined the process of calcination1 whereby the phlogiston of the metal was supposed to have been drawn off4 ,but far from finding that phlogiston or any other substance had been driven off1 he found that something had been taken on3 that the metal absorbed air1 and that the increased weight of the metal corresponded to the amount of air absorbed4 ,meanwhile he was within grasp of two great discoveries1 that of oxygen and of the composition of the air1 which ,priestley made some two years later4 ,the next important inquiry of this great ,frenchman was as to the composition of diamonds4 ,with the great lens of ,tschirnhausen belonging to the ,academy he succeeded in burning up several diamonds1 regardless of expense1 which1 thanks to his inheritance1 he could ignore4 ,in this process he found that a gas was given off which precipitated lime from water1 and proved to be carbonic acid4 ,observing this1 and experimenting with other substances known to give off carbonic acid in the same manner1 he was evidently impressed with the now well-known fact that diamond and charcoal are chemically the same4 ,but if he did really believe it1 he was cautious in expressing his belief fully4 ,we should never have expected1 he says1 to find any relation between charcoal and diamond1 and it would be unreasonable to push this analogy too far2 it only exists because both substances seem to be properly ranged in the class of combustible bodies1 and because they are of all these bodies the most fixed when kept from contact with air4 ,as we have seen1 ,priestley1 in #aggd1 had discovered oxygen1 or dephlogisticated air4 ,four years later ,lavoisier first advanced his theory that this element discovered by ,priestley was the universal acidifying or oxygenating principle1 which1 when combined with charcoal or carbon1 formed carbonic acid2 when combined with sulphur1 formed sulphuric 7or vitriolic7 acid2 with nitrogen1 formed nitric acid1 etc41 and when combined with the metals formed oxides1 or calcides4 ,furthermore1 he postulated the theory that combustion was not due to any such illusive thing as phlogiston1 since this did not exist1 and it seemed to him that the phenomena of combustion heretofore attributed to phlogiston could be explained by the action of the new element oxygen and heat4 ,this was the final blow to the phlogiston theory1 which1 although it had been tottering for some time1 had not been completely overthrown4 ,in #aghg ,lavoisier1 in conjunction with ,guyon de ,morveau1 ,berthollet1 and ,fourcroy1 introduced the reform in chemical nomenclature which until then had remained practically unchanged since alchemical days4 ,such expressions as dephlogisticated and phlogisticated would obviously have little meaning to a generation who were no longer to believe in the existence of phlogiston4 ,it was appropriate that a revolution in chemical thought should be accompanied by a corresponding revolution in chemical names1 and to ,lavoisier belongs chiefly the credit of bringing about this revolution4 ,in his ,elements of ,chemistry he made use of this new nomenclature1 and it seemed so clearly an improvement over the old that the scientific world hastened to adopt it4 ,in this connection ,lavoisier says3 ,we have1 therefore1 laid aside the expression metallic calx altogether1 and have substituted in its place the word oxide4 ,by this it may be seen that the language we have adopted is both copious and expressive4 ,the first or lowest degree of oxygenation in bodies converts them into oxides2 a second degree of additional oxygenation constitutes the class of acids of which the specific names drawn from their particular bases terminate in ous1 as in the nitrous and the sulphurous acids4 ,the third degree of oxygenation changes these into the species of acids distinguished by the termination in ic1 as the nitric and sulphuric acids2 and1 lastly1 we can express a fourth or higher degree of oxygenation by adding the word oxygenated to the name of the acid1 as has already been done with oxygenated muriatic acid47#i7 ,this new work when given to the world was not merely an epoch-making book2 it was revolutionary4 ,it not only discarded phlogiston altogether1 but set forth that metals are simple elements1 not compounds of earth and phlogiston4 ,it upheld ,cavendish's demonstration that water itself1 like air1 is a compound of oxygen with another element4 ,in short1 it was scientific chemistry1 in the modern acceptance of the term4 ,lavoisier's observations on combustion are at once important and interesting3 ,combustion1 he says1 444 is the decomposition of oxygen produced by a combustible body4 ,the oxygen which forms the base of this gas is absorbed by and enters into combination with the burning body1 while the caloric and light are set free4 ,every combustion necessarily supposes oxygenation2 whereas1 on the contrary1 every oxygenation does not necessarily imply concomitant combustion2 because combustion properly so called cannot take place without disengagement of caloric and light4 ,before combustion can take place1 it is necessary that the base of oxygen gas should have greater affinity to the combustible body than it has to caloric2 and this elective attraction1 to use ,bergman's expression1 can only take place at a certain degree of temperature which is different for each combustible substance2 hence the necessity of giving the first motion or beginning to every combustion by the approach of a heated body4 ,this necessity of heating any body we mean to burn depends upon certain considerations which have not hitherto been attended to by any natural philosopher1 for which reason ,i shall enlarge a little upon the subject in this place3 ,nature is at present in a state of equilibrium1 which cannot have been attained until all the spontaneous combustions or oxygenations possible in an ordinary degree of temperature had taken place4444 ,to illustrate this abstract view of the matter by example3 ,let us suppose the usual temperature of the earth a little changed1 and it is raised only to the degree of boiling water2 it is evident that in this case phosphorus1 which is combustible in a considerably lower degree of temperature1 would no longer exist in nature in its pure and simple state1 but would always be procured in its acid or oxygenated state1 and its radical would become one of the substances unknown to chemistry4 ,by gradually increasing the temperature of the earth1 the same circumstance would successively happen to all the bodies capable of combustion2 and1 at the last1 every possible combustion having taken place1 there would no longer exist any combustible body whatever1 and every substance susceptible of the operation would be oxygenated and consequently incombustible4 ,there cannot1 therefore1 exist1 as far as relates to us1 any combustible body but such as are non-combustible at the ordinary temperature of the earth1 or1 what is the same thing in other words1 that it is essential to the nature of every combustible body not to possess the property of combustion unless heated1 or raised to a degree of temperature at which its combustion naturally takes place4 ,when this degree is once produced1 combustion commences1 and the caloric which is disengaged by the decomposition of the oxygen gas keeps up the temperature which is necessary for continuing combustion4 ,when this is not the case--that is1 when the disengaged caloric is not sufficient for keeping up the necessary temperature--the combustion ceases4 ,this circumstance is expressed in the common language by saying that a body burns ill or with difficulty47#aj7 ,it needed the genius of such a man as ,lavoisier to complete the refutation of the false but firmly grounded phlogiston theory1 and against such a book as his ,elements of ,chemistry the feeble weapons of the supporters of the phlogiston theory were hurled in vain4 ,but while chemists1 as a class1 had become converts to the new chemistry before the end of the century1 one man1 ,dr4 ,priestley1 whose work had done so much to found it1 remained unconverted4 ,in this1 as in all his life-work1 he showed himself to be a most remarkable man4 ,davy said of him1 a generation later1 that no other person ever discovered so many new and curious substances as he2 yet to the last he was only an amateur in science1 his profession1 as we know1 being the ministry4 ,there is hardly another case in history of a man not a specialist in science accomplishing so much in original research as did this chemist1 physiologist1 electrician2 the mathematician1 logician1 and moralist2 the theologian1 mental philosopher1 and political economist4 ,he took all knowledge for his field2 but how he found time for his numberless researches and multifarious writings1 along with his every-day duties1 must ever remain a mystery to ordinary mortals4 ,that this marvellously receptive1 flexible mind should have refused acceptance to the clearly logical doctrines of the new chemistry seems equally inexplicable4 ,but so it was4 ,to the very last1 after all his friends had capitulated1 ,priestley kept up the fight4 ,from ,america he sent out his last defy to the enemy1 in #ahjj1 in a brochure entitled ,the ,doctrine of ,phlogiston ,upheld1 etc4 ,in the mind of its author it was little less than a paean of victory2 but all the world beside knew that it was the swan-song of the doctrine of phlogiston4 ,despite the defiance of this single warrior the battle was really lost and won1 and as the century closed antiphlogistic chemistry had practical possession of the field4 ,,iii4 ,,chemistry ,,since ,,the ,,time ,,of ,,dalton ,,john ,,dalton ,,and ,,the ,,atomic ,,theory ,small beginnings as have great endings--sometimes4 ,as a case in point1 note what came of the small1 original effort of a self-trained back-country ,quaker youth named ,john ,dalton1 who along towards the close of the eighteenth century became interested in the weather1 and was led to construct and use a crude water-gauge to test the amount of the rainfall4 ,the simple experiments thus inaugurated led to no fewer than two hundred thousand recorded observations regarding the weather1 which formed the basis for some of the most epochal discoveries in meteorology1 as we have seen4 ,but this was only a beginning4 ,the simple rain-gauge pointed the way to the most important generalization of the nineteenth century in a field of science with which1 to the casual observer1 it might seem to have no alliance whatever4 ,the wonderful theory of atoms1 on which the whole gigantic structure of modern chemistry is founded1 was the logical outgrowth1 in the mind of ,john ,dalton1 of those early studies in meteorology4 ,the way it happened was this3 ,from studying the rainfall1 ,dalton turned naturally to the complementary process of evaporation4 ,he was soon led to believe that vapor exists1 in the atmosphere as an independent gas4 ,but since two bodies cannot occupy the same space at the same time1 this implies that the various atmospheric gases are really composed of discrete particles4 ,these ultimate particles are so small that we cannot see them--cannot1 indeed1 more than vaguely imagine them--yet each particle of vapor1 for example1 is just as much a portion of water as if it were a drop out of the ocean1 or1 for that matter1 the ocean itself4 ,but1 again1 water is a compound substance1 for it may be separated1 as ,cavendish has shown1 into the two elementary substances hydrogen and oxygen4 ,hence the atom of water must be composed of two lesser atoms joined together4 ,imagine an atom of hydrogen and one of oxygen4 ,unite them1 and we have an atom of water2 sever them1 and the water no longer exists2 but whether united or separate the atoms of hydrogen and of oxygen remain hydrogen and oxygen and nothing else4 ,differently mixed together or united1 atoms produce different gross substances2 but the elementary atoms never change their chemical nature--their distinct personality4 ,it was about the year #ahjc that ,dalton first gained a full grasp of the conception of the chemical atom4 ,at once he saw that the hypothesis1 if true1 furnished a marvellous key to secrets of matter hitherto insoluble--questions relating to the relative proportions of the atoms themselves4 ,it is known1 for example1 that a certain bulk of hydrogen gas unites with a certain bulk of oxygen gas to form water4 ,if it be true that this combination consists essentially of the union of atoms one with another 7each single atom of hydrogen united to a single atom of oxygen71 then the relative weights of the original masses of hydrogen and of oxygen must be also the relative weights of each of their respective atoms4 ,if one pound of hydrogen unites with five and one-half pounds of oxygen 7as1 according to ,dalton's experiments1 it did71 then the weight of the oxygen atom must be five and one-half times that of the hydrogen atom4 ,other compounds may plainly be tested in the same way4 ,dalton made numerous tests before he published his theory4 ,he found that hydrogen enters into compounds in smaller proportions than any other element known to him1 and so1 for convenience1 determined to take the weight of the hydrogen atom as unity4 ,the atomic weight of oxygen then becomes 7as given in ,dalton's first table of #ahjc7 #e4e2 that of water 7hydrogen plus oxygen7 being of course #f4e4 ,the atomic weights of about a score of substances are given in ,dalton's first paper1 which was read before the ,literary and ,philosophical ,society of ,manchester1 ,october #ba1 #ahjc4 ,i wonder if ,dalton himself1 great and acute intellect though he had1 suspected1 when he read that paper1 that he was inaugurating one of the most fertile movements ever entered on in the whole history of science8 ,be that as it may1 it is certain enough that ,dalton's contemporaries were at first little impressed with the novel atomic theory4 ,just at this time1 as it chanced1 a dispute was waging in the field of chemistry regarding a matter of empirical fact which must necessarily be settled before such a theory as that of ,dalton could even hope for a bearing4 ,this was the question whether or not chemical elements unite with one another always in definite proportions4 ,berthollet1 the great co-worker with ,lavoisier1 and now the most authoritative of living chemists1 contended that substances combine in almost indefinitely graded proportions between fixed extremes4 ,he held that solution is really a form of chemical combination--a position which1 if accepted1 left no room for argument4 ,but this contention of the master was most actively disputed1 in particular by ,louis ,joseph ,proust1 and all chemists of repute were obliged to take sides with one or the other4 ,for a time the authority of ,berthollet held out against the facts1 but at last accumulated evidence told for ,proust and his followers1 and towards the close of the first decade of our century it came to be generally conceded that chemical elements combine with one another in fixed and definite proportions4 ,more than that4 ,as the analysts were led to weigh carefully the quantities of combining elements1 it was observed that the proportions are not only definite1 but that they bear a very curious relation to one another4 ,if element ,a combines with two different proportions of element ,b to form two compounds1 it appears that the weight of the larger quantity of ,b is an exact multiple of that of the smaller quantity4 ,this curious relation was noticed by ,dr4 ,wollaston1 one of the most accurate of observers1 and a little later it was confirmed by ,johan ,jakob ,berzelius1 the great ,swedish chemist1 who was to be a dominating influence in the chemical world for a generation to come4 ,but this combination of elements in numerical proportions was exactly what ,dalton had noticed as early as #ahjb1 and what bad led him directly to the atomic weights4 ,so the confirmation of this essential point by chemists of such authority gave the strongest confirmation to the atomic theory4 ,during these same years the rising authority of the ,french chemical world1 ,joseph ,louis ,gay-,lussac1 was conducting experiments with gases1 which he had undertaken at first in conjunction with ,humboldt1 but which later on were conducted independently4 ,in #ahji1 the next year after the publication of the first volume of ,dalton's ,new ,system of ,chemical ,philosophy1 ,gay-,lussac published the results of his observations1 and among other things brought out the remarkable fact that gases1 under the same conditions as to temperature and pressure1 combine always in definite numerical proportions as to volume4 ,exactly two volumes of hydrogen1 for example1 combine with one volume of oxygen to form water4 ,moreover1 the resulting compound gas always bears a simple relation to the combining volumes4 ,in the case just cited1 the union of two volumes of hydrogen and one of oxygen results in precisely two volumes of water vapor4 ,naturally enough1 the champions of the atomic theory seized upon these observations of ,gay-,lussac as lending strong support to their hypothesis--all of them1 that is1 but the curiously self-reliant and self-sufficient author of the atomic theory himself1 who declined to accept the observations of the ,french chemist as valid4 ,yet the observations of ,gay-,lussac were correct1 as countless chemists since then have demonstrated anew1 and his theory of combination by volumes became one of the foundation-stones of the atomic theory1 despite the opposition of the author of that theory4 ,the true explanation of ,gay-,lussac's law of combination by volumes was thought out almost immediately by an ,italian savant1 ,amadeo1 ,avogadro1 and expressed in terms of the atomic theory4 ,the fact must be1 said ,avogadro1 that under similar physical conditions every form of gas contains exactly the same number of ultimate particles in a given volume4 ,each of these ultimate physical particles may be composed of two or more atoms 7as in the case of water vapor71 but such a compound atom conducts itself as if it were a simple and indivisible atom1 as regards the amount of space that separates it from its fellows under given conditions of pressure and temperature4 ,the compound atom1 composed of two or more elementary atoms1 ,avogadro proposed to distinguish1 for purposes of convenience1 by the name molecule4 ,it is to the molecule1 considered as the unit of physical structure1 that ,avogadro's law applies4 ,this vastly important distinction between atoms and molecules1 implied in the law just expressed1 was published in #ahaa4 ,four years later1 the famous ,french physicist ,ampere outlined a similar theory1 and utilized the law in his mathematical calculations4 ,and with that the law of ,avogadro dropped out of sight for a full generation4 ,little suspecting that it was the very key to the inner mysteries of the atoms for which they were seeking1 the chemists of the time cast it aside1 and let it fade from the memory of their science4 ,this1 however1 was not strange1 for of course the law of ,avogadro is based on the atomic theory1 and in #ahaa the atomic theory was itself still being weighed in the balance4 ,the law of multiple proportions found general acceptance as an empirical fact2 but many of the leading lights of chemistry still looked askance at ,dalton's explanation of this law4 ,thus ,wollaston1 though from the first he inclined to acceptance of the ,daltonian view1 cautiously suggested that it would be well to use the non-committal word equivalent instead of atom2 and ,davy1 for a similar reason1 in his book of #ahab1 speaks only of proportions1 binding himself to no theory as to what might be the nature of these proportions4 ,at least two great chemists of the time1 however1 adopted the atomic view with less reservation4 ,one of these was ,thomas ,thomson1 professor at ,edinburgh1 who1 in #ahjg1 had given an outline of ,dalton's theory in a widely circulated book1 which first brought the theory to the general attention of the chemical world4 ,the other and even more noted advocate of the atomic theory was ,johan ,jakob ,berzelius4 ,this great ,swedish chemist at once set to work to put the atomic theory to such tests as might be applied in the laboratory4 ,he was an analyst of the utmost skill1 and for years he devoted himself to the determination of the combining weights1 equivalents or proportions1 of the different elements4 ,these determinations1 in so far as they were accurately made1 were simple expressions of empirical facts1 independent of any theory2 but gradually it became more and more plain that these facts all harmonize with the atomic theory of ,dalton4 ,so by common consent the proportionate combining weights of the elements came to be known as atomic weights--the name ,dalton had given them from the first--and the tangible conception of the chemical atom as a body of definite constitution and weight gained steadily in favor4 ,from the outset the idea had had the utmost tangibility in the mind of ,dalton4 ,he had all along represented the different atoms by geometrical symbols--as a circle for oxygen1 a circle enclosing a dot for hydrogen1 and the like--and had represented compounds by placing these symbols of the elements in juxtaposition4 ,berzelius proposed to improve upon this method by substituting for the geometrical symbol the initial of the ,latin name of the element represented--,o for oxygen1 ,h for hydrogen1 and so on--a numerical coefficient to follow the letter as an indication of the number of atoms present in any given compound4 ,this simple system soon gained general acceptance1 and with slight modifications it is still universally employed4 ,every school-boy now is aware that ,h#b,o is the chemical way of expressing the union of two atoms of hydrogen with one of oxygen to form a molecule of water4 ,but such a formula would have had no meaning for the wisest chemist before the day of ,berzelius4 ,the universal fame of the great ,swedish authority served to give general currency to his symbols and atomic weights1 and the new point of view thus developed led presently to two important discoveries which removed the last lingering doubts as to the validity of the atomic theory4 ,in #ahai two ,french physicists1 ,dulong and ,petit1 while experimenting with heat1 discovered that the specific heats of solids 7that is to say1 the amount of heat required to raise the temperature of a given mass to a given degree7 vary inversely as their atomic weights4 ,in the same year ,eilhard ,mitscherlich1 a ,german investigator1 observed that compounds having the same number of atoms to the molecule are disposed to form the same angles of crystallization--a property which he called isomorphism4 ,here1 then1 were two utterly novel and independent sets of empirical facts which harmonize strangely with the supposition that substances are composed of chemical atoms of a determinate weight4 ,this surely could not be coincidence--it tells of law4 ,and so as soon as the claims of ,dulong and ,petit and of ,mitscherlich had been substantiated by other observers1 the laws of the specific heat of atoms1 and of isomorphism1 took their place as new levers of chemical science4 ,with the aid of these new tools an impregnable breastwork of facts was soon piled about the atomic theory4 ,and ,john ,dalton1 the author of that theory1 plain1 provincial ,quaker1 working on to the end in semi-retirement1 became known to all the world and for all time as a master of masters4 ,,humphry ,,davy ,,and ,,electro-,,chemistry ,during those early years of the nineteenth century1 when ,dalton was grinding away at chemical fact and theory in his obscure ,manchester laboratory1 another ,englishman held the attention of the chemical world with a series of the most brilliant and widely heralded researches4 ,this was ,humphry ,davy1 a young man who had conic to ,london in #ahja1 at the instance of ,count ,rumford1 to assume the chair of chemical philosophy in the ,royal ,institution1 which the famous ,american had just founded4 ,here1 under ,davy's direction1 the largest voltaic battery yet constructed had been put in operation1 and with its aid the brilliant young experimenter was expected almost to perform miracles4 ,and indeed he scarcely disappointed the expectation1 for with the aid of his battery he transformed so familiar a substance as common potash into a metal which was not only so light that it floated on water1 but possessed the seemingly miraculous property of bursting into flames as soon as it came in contact with that fire-quenching liquid4 ,if this were not a miracle1 it had for the popular eye all the appearance of the miraculous4 ,what ,davy really had done was to decompose the potash1 which hitherto had been supposed to be elementary1 liberating its oxygen1 and thus isolating its metallic base1 which he named potassium4 ,the same thing was done with soda1 and the closely similar metal sodium was discovered--metals of a unique type1 possessed of a strange avidity for oxygen1 and capable of seizing on it even when it is bound up in the molecules of water4 ,considered as mere curiosities1 these discoveries were interesting1 but aside from that they were of great theoretical importance1 because they showed the compound nature of some familiar chemicals that had been regarded as elements4 ,several other elementary earths met the same fate when subjected to the electrical influence2 the metals barium1 calcium1 and strontium being thus discovered4 ,thereafter ,davy always referred to the supposed elementary substances 7including oxygen1 hydrogen1 and the rest7 as unde-compounded bodies4 ,these resist all present efforts to decompose them1 but how can one know what might not happen were they subjected to an influence1 perhaps some day to be discovered1 which exceeds the battery in power as the battery exceeds the blowpipe8 ,another and even more important theoretical result that flowed from ,davy's experiments during this first decade of the century was the proof that no elementary substances other than hydrogen and oxygen are produced when pure water is decomposed by the electric current4 ,it was early noticed by ,davy and others that when a strong current is passed through water1 alkalies appear at one pole of the battery and acids at the other1 and this though the water used were absolutely pure4 ,this seemingly told of the creation of elements--a transmutation but one step removed from the creation of matter itself--under the influence of the new force4 ,it was one of ,davy's greatest triumphs to prove1 in the series of experiments recorded in his famous ,bakerian lecture of #ahjf1 that the alleged creation of elements did not take place1 the substances found at the poles of the battery having been dissolved from the walls of the vessels in which the water experimented upon had been placed4 ,thus the same implement which had served to give a certain philosophical warrant to the fading dreams of alchemy banished those dreams peremptorily from the domain of present science4 ,as early as #ahjj1 writes ,davy1 ,i had found that when separate portions of distilled water1 filling two glass tubes1 connected by moist bladders1 or any moist animal or vegetable substances1 were submitted to the electrical action of the pile of ,volta by means of gold wires1 a nitro-muriatic solution of gold appeared in the tube containing the positive wire1 or the wire transmitting the electricity1 and a solution of soda in the opposite tube2 but ,i soon ascertained that the muriatic acid owed its existence to the animal or vegetable matters employed2 for when the same fibres of cotton were made use of in successive experiments1 and washed after every process in a weak solution of nitric acid1 the water in the apparatus containing them1 though acted on for a great length of time with a very strong power1 at last produced no effects upon nitrate of silver4 ,in cases when ,i had procured much soda1 the glass at its point of contact with the wire seemed considerably corroded2 and ,i was confirmed in my idea of referring the production of the alkali principally to this source1 by finding that no fixed saline matter could be obtained by electrifying distilled water in a single agate cup from two points of platina with the ,voltaic battery4 ,mr4 ,sylvester1 however1 in a paper published in ,mr4 ,nicholson's journal for last ,august1 states that though no fixed alkali or muriatic acid appears when a single vessel is employed1 yet that they are both formed when two vessels are used4 ,and to do away with all objections with regard to vegetable substances or glass1 he conducted his process in a vessel made of baked tobacco-pipe clay inserted in a crucible of platina4 ,i have no doubt of the correctness of his results2 but the conclusion appears objectionable4 ,he conceives1 that he obtained fixed alkali1 because the fluid after being heated and evaporated left a matter that tinged turmeric brown1 which would have happened had it been lime1 a substance that exists in considerable quantities in all pipe-clay2 and even allowing the presence of fixed alkali1 the materials employed for the manufacture of tobacco-pipes are not at all such as to exclude the combinations of this substance4 ,i resumed the inquiry2 ,i procured small cylindrical cups of agate of the capacity of about one-quarter of a cubic inch each4 ,they were boiled for some hours in distilled water1 and a piece of very white and transparent amianthus that had been treated in the same way was made then to connect together2 they were filled with distilled water and exposed by means of two platina wires to a current of electricity1 from one hundred and fifty pairs of plates of copper and zinc four inches square1 made active by means of solution of alum4 ,after forty-eight hours the process was examined3 ,paper tinged with litmus plunged into the tube containing the transmitting or positive wire was immediately strongly reddened4 ,paper colored by turmeric introduced into the other tube had its color much deepened2 the acid matter gave a very slight degree of turgidness to solution of nitrate of soda4 ,the fluid that affected turmeric retained this property after being strongly boiled2 and it appeared more vivid as the quantity became reduced by evaporation2 carbonate of ammonia was mixed with it1 and the whole dried and exposed to a strong heat2 a minute quantity of white matter remained1 which1 as far as my examinations could go1 had the properties of carbonate of soda4 ,i compared it with similar minute portions of the pure carbonates of potash1 and similar minute portions of the pure carbonates of potash and soda4 ,it was not so deliquescent as the former of these bodies1 and it formed a salt with nitric acid1 which1 like nitrate of soda1 soon attracted moisture from a damp atmosphere and became fluid4 ,this result was unexpected1 but it was far from convincing me that the substances which were obtained were generated4 ,in a similar process with glass tubes1 carried on under exactly the same circumstances and for the same time1 ,i obtained a quantity of alkali which must have been more than twenty times greater1 but no traces of muriatic acid4 ,there was much probability that the agate contained some minute portion of saline matter1 not easily detected by chemical analysis1 either in combination or intimate cohesion in its pores4 ,to determine this1 ,i repeated this a second1 a third1 and a fourth time4 ,in the second experiment turbidness was still produced by a solution of nitrate of silver in the tube containing the acid1 but it was less distinct2 in the third process it was barely perceptible2 and in the fourth process the two fluids remained perfectly clear after the mixture4 ,the quantity of alkaline matter diminished in every operation2 and in the last process1 though the battery had been kept in great activity for three days1 the fluid possessed1 in a very slight degree1 only the power of acting on paper tinged with turmeric2 but its alkaline property was very sensible to litmus paper slightly reddened1 which is a much more delicate test2 and after evaporation and the process by carbonate of ammonia1 a barely perceptible quantity of fixed alkali was still left4 ,the acid matter in the other tube was abundant2 its taste was sour2 it smelled like water over which large quantities of nitrous gas have been long kept2 it did not effect solution of muriate of barytes2 and a drop of it placed upon a polished plate of silver left1 after evaporation1 a black stain1 precisely similar to that produced by extremely diluted nitrous acid4 ,after these results ,i could no longer doubt that some saline matter existing in the agate tubes had been the source of the acid matter capable of precipitating nitrate of silver and much of the alkali4 ,four additional repetitions of the process1 however1 convinced me that there was likewise some other cause for the presence of this last substance2 for it continued to appear to the last in quantities sufficiently distinguishable1 and apparently equal in every case4 ,i had used every precaution1 ,i had included the tube in glass vessels out of the reach of the circulating air2 all the acting materials had been repeatedly washed with distilled water2 and no part of them in contact with the fluid had been touched by the fingers4 ,the only substance that ,i could now conceive as furnishing the fixed alkali was the water itself4 ,this water appeared pure by the tests of nitrate of silver and muriate of barytes2 but potash of soda1 as is well known1 rises in small quantities in rapid distillation2 and the ,new ,river water which ,i made use of contains animal and vegetable impurities1 which it was easy to conceive might furnish neutral salts capable of being carried over in vivid ebullition47#a7 ,further experiment proved the correctness of this inference1 and the last doubt as to the origin of the puzzling chemical was dispelled4 ,though the presence of the alkalies and acids in the water was explained1 however1 their respective migrations to the negative and positive poles of the battery remained to be accounted for4 ,davy's classical explanation assumed that different elements differ among themselves as to their electrical properties1 some being positively1 others negatively1 electrified4 ,electricity and chemical affinity1 he said1 apparently are manifestations of the same force1 acting in the one case on masses1 in the other on particles4 ,electro-positive particles unite with electro-negative particles to form chemical compounds1 in virtue of the familiar principle that opposite electricities attract one another4 ,when compounds are decomposed by the battery1 this mutual attraction is overcome by the stronger attraction of the poles of the battery itself4 ,this theory of binary composition of all chemical compounds1 through the union of electro-positive and electro-negative atoms or molecules1 was extended by ,berzelius1 and made the basis of his famous system of theoretical chemistry4 ,this theory held that all inorganic compounds1 however complex their composition1 are essentially composed of such binary combinations4 ,for many years this view enjoyed almost undisputed sway4 ,it received what seemed strong confirmation when ,faraday showed the definite connection between the amount of electricity employed and the amount of decomposition produced in the so-called electrolyte4 ,but its claims were really much too comprehensive1 as subsequent discoveries proved4 ,,organic ,,chemistry ,,and ,,the ,,idea ,,of ,,the ,,molecule ,when ,berzelius first promulgated his binary theory he was careful to restrict its unmodified application to the compounds of the inorganic world4 ,at that time1 and for a long time thereafter1 it was supposed that substances of organic nature had some properties that kept them aloof from the domain of inorganic chemistry4 ,it was little doubted that a so-called vital force operated here1 replacing or modifying the action of ordinary chemical affinity4 ,it was1 indeed1 admitted that organic compounds are composed of familiar elements--chiefly carbon1 oxygen1 hydrogen1 and nitrogen2 but these elements were supposed to be united in ways that could not be imitated in the domain of the non-living4 ,it was regarded almost as an axiom of chemistry that no organic compound whatever could be put together from its elements--synthesized--in the laboratory4 ,to effect the synthesis of even the simplest organic compound1 it was thought that the vital force must be in operation4 ,therefore a veritable sensation was created in the chemical world when1 in the year #ahbh1 it was announced that the young ,german chemist1 ,friedrich ,wohler1 formerly pupil of ,berzelius1 and already known as a coming master1 had actually synthesized the well-known organic product urea in his laboratory at ,sacrow4 ,the exception which proves the rule is something never heard of in the domain of logical science4 ,natural law knows no exceptions4 ,so the synthesis of a single organic compound sufficed at a blow to break down the chemical barrier which the imagination of the fathers of the science had erected between animate and inanimate nature4 ,thenceforth the philosophical chemist would regard the plant and animal organisms as chemical laboratories in which conditions are peculiarly favorable for building up complex compounds of a few familiar elements1 under the operation of universal chemical laws4 ,the chimera vital force could no longer gain recognition in the domain of chemistry4 ,now a wave of interest in organic chemistry swept over the chemical world1 and soon the study of carbon compounds became as much the fashion as electrochemistry had been in the1 preceding generation4 ,foremost among the workers who rendered this epoch of organic chemistry memorable were ,justus ,liebig in ,germany and ,jean ,baptiste ,andre ,dumas in ,france1 and their respective pupils1 ,charles ,frederic ,gerhardt and ,augustus ,laurent4 ,wohler1 too1 must be named in the same breath1 as also must ,louis ,pasteur1 who1 though somewhat younger than the others1 came upon the scene in time to take chief part in the most important of the controversies that grew out of their labors4 ,several years earlier than this the way had been paved for the study of organic substances by ,gay-,lussac's discovery1 made in #ahae1 that a certain compound of carbon and nitrogen1 which he named cyanogen1 has a peculiar degree of stability which enables it to retain its identity and enter into chemical relations after the manner of a simple body4 ,a year later ,ampere discovered that nitrogen and hydrogen1 when combined in certain proportions to form what he called ammonium1 have the same property4 ,berzelius had seized upon this discovery of the compound radical1 as it was called1 because it seemed to lend aid to his dualistic theory4 ,he conceived the idea that all organic compounds are binary unions of various compound radicals with an atom of oxygen1 announcing this theory in #ahah4 ,ten years later1 ,liebig and ,wohler undertook a joint investigation which resulted in proving that compound radicals are indeed very abundant among organic substances4 ,thus the theory of ,berzelius seemed to be substantiated1 and organic chemistry came to be defined as the chemistry of compound radicals4 ,but even in the day of its seeming triumph the dualistic theory was destined to receive a rude shock4 ,this came about through the investigations of ,dumas1 who proved that in a certain organic substance an atom of hydrogen may be removed and an atom of chlorine substituted in its place without destroying the integrity of the original compound--much as a child might substitute one block for another in its play-house4 ,such a substitution would be quite consistent with the dualistic theory1 were it not for the very essential fact that hydrogen is a powerfully electro-positive element1 while chlorine is as strongly electro-negative4 ,hence the compound radical which united successively with these two elements must itself be at one time electro-positive1 at another electro-negative--a seeming inconsistency which threw the entire ,berzelian theory into disfavor4 ,in its place there was elaborated1 chiefly through the efforts of ,laurent and ,gerhardt1 a conception of the molecule as a unitary structure1 built up through the aggregation of various atoms1 in accordance with elective affinities whose nature is not yet understood ,a doctrine of nuclei and a doctrine of types of molecular structure were much exploited1 and1 like the doctrine of compound radicals1 became useful as aids to memory and guides for the analyst1 indicating some of the plans of molecular construction1 though by no means penetrating the mysteries of chemical affinity4 ,they are classifications rather than explanations of chemical unions4 ,but at least they served an important purpose in giving definiteness to the idea of a molecular structure built of atoms as the basis of all substances4 ,now at last the word molecule came to have a distinct meaning1 as distinct from atom1 in the minds of the generality of chemists1 as it had had for ,avogadro a third of a century before4 ,avogadro's hypothesis that there are equal numbers of these molecules in equal volumes of gases1 under fixed conditions1 was revived by ,gerhardt1 and a little later1 under the championship of ,cannizzaro1 was exalted to the plane of a fixed law4 ,thenceforth the conception of the molecule was to be as dominant a thought in chemistry as the idea of the atom had become in a previous epoch4 ,,chemical ,,affinity ,of course the atom itself was in no sense displaced1 but ,avogadro's law soon made it plain that the atom had often usurped territory that did not really belong to it4 ,in many cases the chemists had supposed themselves dealing with atoms as units where the true unit was the molecule4 ,in the case of elementary gases1 such as hydrogen and oxygen1 for example1 the law of equal numbers of molecules in equal spaces made it clear that the atoms do not exist isolated1 as had been supposed4 ,since two volumes of hydrogen unite with one volume of oxygen to form two volumes of water vapor1 the simplest mathematics show1 in the light of ,avogadro's law1 not only that each molecule of water must contain two hydrogen atoms 7a point previously in dispute71 but that the original molecules of hydrogen and oxygen must have been composed in each case of two atoms---else how could one volume of oxygen supply an atom for every molecule of two volumes of water8 ,what1 then1 does this imply8 ,why1 that the elementary atom has an avidity for other atoms1 a longing for companionship1 an affinity--call it what you will--which is bound to be satisfied if other atoms are in the neighborhood4 ,placed solely among atoms of its own kind1 the oxygen atom seizes on a fellow oxygen atom1 and in all their mad dancings these two mates cling together--possibly revolving about each other in miniature planetary orbits4 ,precisely the same thing occurs among the hydrogen atoms4 ,but now suppose the various pairs of oxygen atoms come near other pairs of hydrogen atoms 7under proper conditions which need not detain us here71 then each oxygen atom loses its attachment for its fellow1 and flings itself madly into the circuit of one of the hydrogen couplets1 and--presto6--there are only two molecules for every three there were before1 and free oxygen and hydrogen have become water4 ,the whole process1 stated in chemical phraseology1 is summed up in the statement that under the given conditions the oxygen atoms had a greater affinity for the hydrogen atoms than for one another4 ,as chemists studied the actions of various kinds of atoms1 in regard to their unions with one another to form molecules1 it gradually dawned upon them that not all elements are satisfied with the same number of companions4 ,some elements ask only one1 and refuse to take more2 while others link themselves1 when occasion offers1 with two1 three1 four1 or more4 ,thus we saw that oxygen forsook a single atom of its own kind and linked itself with two atoms of hydrogen4 ,clearly1 then1 the oxygen atom1 like a creature with two hands1 is able to clutch two other atoms4 ,but we have no proof that under any circumstances it could hold more than two4 ,its affinities seem satisfied when it has two bonds4 ,but1 on the other hand1 the atom of nitrogen is able to hold three atoms of hydrogen1 and does so in the molecule of ammonium 7,,nh#c72 while the carbon atom can hold four atoms of hydrogen or two atoms of oxygen4 ,evidently1 then1 one atom is not always equivalent to another atom of a different kind in combining powers4 ,a recognition of this fact by ,frankland about #aheb1 and its further investigation by others 7notably ,a4 ,kekule and ,a4 ,s4 ,couper71 led to the introduction of the word equivalent into chemical terminology in a new sense1 and in particular to an understanding of the affinities or valency of different elements1 which proved of the most fundamental importance4 ,thus it was shown that1 of the four elements that enter most prominently into organic compounds1 hydrogen can link itself with only a single bond to any other element--it has1 so to speak1 but a single hand with which to grasp--while oxygen has capacity for two bonds1 nitrogen for three 7possibly for five71 and carbon for four4 ,the words monovalent1 divalent1 trivalent1 tretrava-lent1 etc41 were coined to express this most important fact1 and the various elements came to be known as monads1 diads1 triads1 etc4 ,just why different elements should differ thus in valency no one as yet knows2 it is an empirical fact that they do4 ,and once the nature of any element has been determined as regards its valency1 a most important insight into the possible behavior of that element has been secured4 ,thus a consideration of the fact that hydrogen is monovalent1 while oxygen is divalent1 makes it plain that we must expect to find no more than three compounds of these two elements--namely1 ,h--,o--7written ,,ho by the chemist1 and called hydroxyl72 ,h--,o--,h 7,h#b,o1 or water71 and ,h--,o--,o--,h 7,h#b,o#b1 or hydrogen peroxide74 ,it will be observed that in the first of these compounds the atom of oxygen stands1 so to speak1 with one of its hands free1 eagerly reaching out1 therefore1 for another companion1 and hence1 in the language of chemistry1 forming an unstable compound4 ,again1 in the third compound1 though all hands are clasped1 yet one pair links oxygen with oxygen2 and this also must be an unstable union1 since the avidity of an atom for its own kind is relatively weak4 ,thus the well-known properties of hydrogen peroxide are explained1 its easy decomposition1 and the eagerness with which it seizes upon the elements of other compounds4 ,but the molecule of water1 on the other hand1 has its atoms arranged in a state of stable equilibrium1 all their affinities being satisfied4 ,each hydrogen atom has satisfied its own affinity by clutching the oxygen atom2 and the oxygen atom has both its bonds satisfied by clutching back at the two hydrogen atoms4 ,therefore the trio1 linked in this close bond1 have no tendency to reach out for any other companion1 nor1 indeed1 any power to hold another should it thrust itself upon them4 ,they form a stable compound1 which under all ordinary circumstances will retain its identity as a molecule of water1 even though the physical mass of which it is a part changes its condition from a solid to a gas from ice to vapor4 ,but a consideration of this condition of stable equilibrium in the molecule at once suggests a new question3 ,how can an aggregation of atoms1 having all their affinities satisfied1 take any further part in chemical reactions8 ,seemingly such a molecule1 whatever its physical properties1 must be chemically inert1 incapable of any atomic readjustments4 ,and so in point of fact it is1 so long as its component atoms cling to one another unremittingly4 ,but this1 it appears1 is precisely what the atoms are little prone to do4 ,it seems that they are fickle to the last degree in their individual attachments1 and are as prone to break away from bondage as they are to enter into it4 ,thus the oxygen atom which has just flung itself into the circuit of two hydrogen atoms1 the next moment flings itself free again and seeks new companions4 ,it is for all the world like the incessant change of partners in a rollicking dance4 ,this incessant dissolution and reformation of molecules in a substance which as a whole remains apparently unchanged was first fully appreciated by ,ste4-,claire ,deville1 and by him named dissociation4 ,it is a process which goes on much more actively in some compounds than in others1 and very much more actively under some physical conditions 7such as increase of temperature7 than under others4 ,but apparently no substances at ordinary temperatures1 and no temperature above the absolute zero1 are absolutely free from its disturbing influence4 ,hence it is that molecules having all the valency of their atoms fully satisfied do not lose their chemical activity--since each atom is momentarily free in the exchange of partners1 and may seize upon different atoms from its former partners1 if those it prefers are at hand4 ,while1 however1 an appreciation of this ceaseless activity of the atom is essential to a proper understanding of its chemical efficiency1 yet from another point of view the saturated molecule--that is1 the molecule whose atoms have their valency all satisfied--may be thought of as a relatively fixed or stable organism4 ,even though it may presently be torn down1 it is for the time being a completed structure2 and a consideration of the valency of its atoms gives the best clew that has hitherto been obtainable as to the character of its architecture4 ,how important this matter of architecture of the molecule--of space relations of the atoms--may be--was demonstrated as long ago as #ahbc1 when ,liebig and ,wohler proved1 to the utter bewilderment of the chemical world1 that two substances may have precisely the same chemical constitution--the same number and kind of atoms--and yet differ utterly in physical properties4 ,the word isomerism was coined by ,berzelius to express this anomalous condition of things1 which seemed to negative the most fundamental truths of chemistry4 ,naming the condition by no means explained it1 but the fact was made clear that something besides the mere number and kind of atoms is important in the architecture of a molecule4 ,it became certain that atoms are not thrown together haphazard to build a molecule1 any more than bricks are thrown together at random to form a house4 ,how delicate may be the gradations of architectural design in building a molecule was well illustrated about #ahej1 when ,pasteur discovered that some carbon compounds--as certain sugars--can only be distinguished from one another1 when in solution1 by the fact of their twisting or polarizing a ray of light to the left or to the right1 respectively4 ,but no inkling of an explanation of these strange variations of molecular structure came until the discovery of the law of valency4 ,then much of the mystery was cleared away2 for it was plain that since each atom in a molecule can hold to itself only a fixed number of other atoms1 complex molecules must have their atoms linked in definite chains or groups4 ,and it is equally plain that where the atoms are numerous1 the exact plan of grouping may sometimes be susceptible of change without doing violence to the law of valency4 ,it is in such cases that isomerism is observed to occur4 ,by paying constant heed to this matter of the affinities1 chemists are able to make diagrammatic pictures of the plan of architecture of any molecule whose composition is known4 ,in the simple molecule of water 7,h#b,o71 for example1 the two hydrogen atoms must have released each other before they could join the oxygen1 and the manner of linking must apparently be that represented in the graphic formula ,h--,o--,h4 ,with molecules composed of a large number of atoms1 such graphic representation of the scheme of linking is of course increasingly difficult1 yet1 with the affinities for a guide1 it is always possible4 ,of course no one supposes that such a formula1 written in a single plane1 can possibly represent the true architecture of the molecule3 it is at best suggestive or diagrammatic rather than pictorial4 ,nevertheless1 it affords hints as to the structure of the molecule such as the fathers of chemistry would not have thought it possible ever to attain4 ,,periodicity ,,of ,,atomic ,,weights ,these utterly novel studies of molecular architecture may seem at first sight to take from the atom much of its former prestige as the all-important personage of the chemical world4 ,since so much depends upon the mere position of the atoms1 it may appear that comparatively little depends upon the nature of the atoms themselves4 ,but such a view is incorrect1 for on closer consideration it will appear that at no time has the atom been seen to renounce its peculiar personality4 ,within certain limits the character of a molecule may be altered by changing the positions of its atoms 7just as different buildings may be constructed of the same bricks71 but these limits are sharply defined1 and it would be as impossible to exceed them as it would be to build a stone building with bricks4 ,from first to last the brick remains a brick1 whatever the style of architecture it helps to construct2 it never becomes a stone4 ,and just as closely does each atom retain its own peculiar properties1 regardless of its surroundings4 ,thus1 for example1 the carbon atom may take part in the formation at one time of a diamond1 again of a piece of coal1 and yet again of a particle of sugar1 of wood fibre1 of animal tissue1 or of a gas in the atmosphere2 but from first to last--from glass-cutting gem to intangible gas--there is no demonstrable change whatever in any single property of the atom itself4 ,so far as we know1 its size1 its weight1 its capacity for vibration or rotation1 and its inherent affinities1 remain absolutely unchanged throughout all these varying fortunes of position and association4 ,and the same thing is true of every atom of all of the seventy-odd elementary substances with which the modern chemist is acquainted4 ,every one appears always to maintain its unique integrity1 gaining nothing and losing nothing4 ,all this being true1 it would seem as if the position of the ,daltonian atom as a primordial bit of matter1 indestructible and non-transmutable1 had been put to the test by the chemistry of our century1 and not found wanting4 ,since those early days of the century when the electric battery performed its miracles and seemingly reached its limitations in the hands of ,davy1 many new elementary substances have been discovered1 but no single element has been displaced from its position as an undecomposable body4 ,rather have the analyses of the chemist seemed to make it more and more certain that all elementary atoms are in truth what ,john ,herschel called them1 manufactured articles--primordial1 changeless1 indestructible4 ,and yet1 oddly enough1 it has chanced that hand in hand with the experiments leading to such a goal have gone other experiments arid speculations of exactly the opposite tenor4 ,in each generation there have been chemists among the leaders of their science who have refused to admit that the so-called elements are really elements at all in any final sense1 and who have sought eagerly for proof which might warrant their scepticism4 ,the first bit of evidence tending to support this view was furnished by an ,english physician1 ,dr4 ,william ,prout1 who in #ahae called attention to a curious relation to be observed between the atomic weight of the various elements4 ,accepting the figures given by the authorities of the time 7notably ,thomson and ,berzelius71 it appeared that a strikingly large proportion of the atomic weights were exact multiples of the weight of hydrogen1 and that others differed so slightly that errors of observation might explain the discrepancy4 ,prout felt that it could not be accidental1 and he could think of no tenable explanation1 unless it be that the atoms of the various alleged elements are made up of different fixed numbers of hydrogen atoms4 ,could it be that the one true element--the one primal matter--is hydrogen1 and that all other forms of matter are but compounds of this original substance8 ,prout advanced this startling idea at first tentatively1 in an anonymous publication2 but afterwards he espoused it openly and urged its tenability4 ,coming just after ,davy's dissociation of some supposed elements1 the idea proved alluring1 and for a time gained such popularity that chemists were disposed to round out the observed atomic weights of all elements into whole numbers4 ,but presently renewed determinations of the atomic weights seemed to discountenance this practice1 and ,prout's alleged law fell into disrepute4 ,it was revived1 however1 about #ahdj1 by ,dumas1 whose great authority secured it a respectful hearing1 and whose careful redetermination of the weight of carbon1 making it exactly twelve times that of hydrogen1 aided the cause4 ,subsequently ,stas1 the pupil of ,dumas1 undertook a long series of determinations of atomic weights1 with the expectation of confirming the ,proutian hypothesis4 ,but his results seemed to disprove the hypothesis1 for the atomic weights of many elements differed from whole numbers by more1 it was thought1 than the limits of error of the experiments4 ,it was noteworthy1 however1 that the confidence of ,dumas was not shaken1 though he was led to modify the hypothesis1 and1 in accordance with previous suggestions of ,clark and of ,marignac1 to recognize as the primordial element1 not hydrogen itself1 but an atom half the weight1 or even one-fourth the weight1 of that of hydrogen1 of which primordial atom the hydrogen atom itself is compounded4 ,but even in this modified form the hypothesis found great opposition from experimental observers4 ,in #ahfd1 however1 a novel relation between the weights of the elements and their other characteristics was called to the attention of chemists by ,professor ,john ,a4 ,r4 ,newlands1 of ,london1 who had noticed that if the elements are arranged serially in the numerical order of their atomic weights1 there is a curious recurrence of similar properties at intervals of eight elements ,this so-called law of octaves attracted little immediate attention1 but the facts it connotes soon came under the observation of other chemists1 notably of ,professors ,gustav ,hinrichs in ,america1 ,dmitri ,mendeleeff in ,russia1 and ,lothar ,meyer in ,germany4 ,mendeleeff gave the discovery fullest expression1 explicating it in #ahfi1 under the title of the periodic law4 ,though this early exposition of what has since been admitted to be a most important discovery was very fully outlined1 the generality of chemists gave it little heed till a decade or so later1 when three new elements1 gallium1 scandium1 and germanium1 were discovered1 which1 on being analyzed1 were quite unexpectedly found to fit into three gaps which ,mendeleeff had left in his periodic scale4 ,in effect the periodic law had enabled ,mendeleeff to predicate the existence of the new elements years before they were discovered4 ,surely a system that leads to such results is no mere vagary4 ,so very soon the periodic law took its place as one of the most important generalizations of chemical science4 ,this law of periodicity was put forward as an expression of observed relations independent of hypothesis2 but of course the theoretical bearings of these facts could not be overlooked4 ,as ,professor ,j4 ,h4 ,gladstone has said1 it forces upon us the conviction that the elements are not separate bodies created without reference to one another1 but that they have been originally fashioned1 or have been built up1 from one another1 according to some general plan4 ,it is but a short step from that proposition to the ,proutian hypothesis4 ,,new ,,weapons--,,spectroscope ,,and ,,camera ,but the atomic weights are not alone in suggesting the compound nature of the alleged elements4 ,evidence of a totally different kind has contributed to the same end1 from a source that could hardly have been imagined when the ,proutian hypothesis1 was formulated1 through the tradition of a novel weapon to the armamentarium of the chemist--the spectroscope4 ,the perfection of this instrument1 in the hands of two ,german scientists1 ,gustav ,robert ,kirchhoff and ,robert ,wilhelm ,bunsen1 came about through the investigation1 towards the middle of the century1 of the meaning of the dark lines which had been observed in the solar spectrum by ,fraunhofer as early as #ahae1 and by ,wollaston a decade earlier4 ,it was suspected by ,stokes and by ,fox ,talbot in ,england1 but first brought to demonstration by ,kirchhoff and ,bunsen1 that these lines1 which were known to occupy definite positions in the spectrum1 are really indicative of particular elementary substances4 ,by means of the spectroscope1 which is essentially a magnifying lens attached to a prism of glass1 it is possible to locate the lines with great accuracy1 and it was soon shown that here was a new means of chemical analysis of the most exquisite delicacy4 ,it was found1 for example1 that the spectroscope could detect the presence of a quantity of sodium so infinitesimal as the one two-hundred-thousandth of a grain4 ,but what was even more important1 the spectroscope put no limit upon the distance of location of the substance it tested1 provided only that sufficient light came from it4 ,the experiments it recorded might be performed in the sun1 or in the most distant stars or nebulae2 indeed1 one of the earliest feats of the instrument was to wrench from the sun the secret of his chemical constitution4 ,to render the utility of the spectroscope complete1 however1 it was necessary to link with it another new chemical agency--namely1 photography4 ,this now familiar process is based on the property of light to decompose certain unstable compounds of silver1 and thus alter their chemical composition4 ,davy and ,wedgwood barely escaped the discovery of the value of the photographic method early in the nineteenth century4 ,their successors quite overlooked it until about #ahbf1 when ,louis ,j4 ,m4 ,daguerre1 the ,french chemist1 took the matter in hand1 and after many years of experimentation brought it to relative perfection in #ahci1 in which year the famous daguerreotype first brought the matter to popular attention4 ,in the same year ,mr4 ,fox ,talbot read a paper on the subject before the ,royal ,society1 and soon afterwards the efforts of ,herschel and numerous other natural philosophers contributed to the advancement of the new method4 ,in #ahdc ,dr4 ,john ,w4 ,draper1 the famous ,english-,american chemist and physiologist1 showed that by photography the ,fraunhofer lines in the solar spectrum might be mapped with absolute accuracy2 also proving that the silvered film revealed many lines invisible to the unaided eye4 ,the value of this method of observation was recognized at once1 and1 as soon as the spectroscope was perfected1 the photographic method1 in conjunction with its use1 became invaluable to the chemist4 ,by this means comparisons of spectra may be made with a degree of accuracy not otherwise obtainable2 and1 in case of the stars1 whole clusters of spectra may be placed on record at a single observation4 ,as the examination of the sun and stars proceeded1 chemists were amazed or delighted1 according to their various preconceptions1 to witness the proof that many familiar terrestrial elements are to be found in the celestial bodies4 ,but what perhaps surprised them most was to observe the enormous preponderance in the sidereal bodies of the element hydrogen4 ,not only are there vast quantities of this element in the sun's atmosphere1 but some other suns appeared to show hydrogen lines almost exclusively in their spectra4 ,presently it appeared that the stars of which this is true are those white stars1 such as ,sirius1 which had been conjectured to be the hottest2 whereas stars that are only red-hot1 like our sun1 show also the vapors of many other elements1 including iron and other metals4 ,in #ahgh ,professor ,j4 ,norman ,lockyer1 in a paper before the ,royal ,society1 called attention to the possible significance of this series of observations4 ,he urged that the fact of the sun showing fewer elements than are observed here on the cool earth1 while stars much hotter than the sun show chiefly one element1 and that one hydrogen1 the lightest of known elements1 seemed to give color to the possibility that our alleged elements are really compounds1 which at the temperature of the hottest stars may be decomposed into hydrogen1 the latter element itself being also doubtless a compound1 which might be resolved under yet more trying conditions4 ,here1 then1 was what might be termed direct experimental evidence for the hypothesis of ,prout4 ,unfortunately1 however1 it is evidence of a kind which only a few experts are competent to discuss--so very delicate a matter is the spectral analysis of the stars4 ,what is still more unfortunate1 the experts do not agree among themselves as to the validity of ,professor ,lockyer's conclusions4 ,some1 like ,professor ,crookes1 have accepted them with acclaim1 hailing ,lockyer as the ,darwin of the inorganic world1 while others have sought a different explanation of the facts he brings forward4 ,as yet it cannot be said that the controversy has been brought to final settlement4 ,still1 it is hardly to be doubted that now1 since the periodic law has seemed to join hands with the spectroscope1 a belief in the compound nature of the so-called elements is rapidly gaining ground among chemists4 ,more and more general becomes the belief that the ,daltonian atom is really a compound radical1 and that back of the seeming diversity of the alleged elements is a single form of primordial matter4 ,indeed1 in very recent months1 direct experimental evidence for this view has at last come to hand1 through the study of radio-active substances4 ,in a later chapter we shall have occasion to inquire how this came about4 ,,iv4 ,,anatomy ,,and ,,physiology ,,in ,,the ,,eighteenth ,,century ,,albrecht ,,von ,,haller ,an epoch in physiology was made in the eighteenth century by the genius and efforts of ,albrecht von ,haller 7#agjh-aggg71 of ,berne1 who is perhaps as worthy of the title ,the ,great as any philosopher who has been so christened by his contemporaries since the time of ,hippocrates4 ,celebrated as a physician1 he was proficient in various fields1 being equally famed in his own time as poet1 botanist1 and statesman1 and dividing his attention between art and science4 ,as a child ,haller was so sickly that he was unable to amuse himself with the sports and games common to boys of his age1 and so passed most of his time poring over books4 ,when ten years of age he began writing poems in ,latin and ,german1 and at fifteen entered the ,university of ,tubingen4 ,at seventeen he wrote learned articles in opposition to certain accepted doctrines1 and at nineteen he received his degree of doctor4 ,soon after this he visited ,england1 where his zeal in dissecting brought him under suspicion of grave-robbery1 which suspicion made it expedient for him to return to the ,continent4 ,after studying botany in ,basel for some time he made an extended botanical journey through ,switzerland1 finally settling in his native city1 ,berne1 as a practising physician4 ,during this time he did not neglect either poetry or botany1 publishing anonymously a collection of poems4 ,in #agcf he was called to ,gottingen as professor of anatomy1 surgery1 chemistry1 and botany4 ,during his labors in the university he never neglected his literary work1 sometimes living and sleeping for days and nights together in his library1 eating his meals while delving in his books1 and sleeping only when actually compelled to do so by fatigue4 ,during all this time he was in correspondence with savants from all over the world1 and it is said of him that he never left a letter of any kind unanswered4 ,haller's greatest contribution to medical science was his famous doctrine of irritability1 which has given him the name of father of modern nervous physiology1 just as ,harvey is called the father of the modern physiology of the blood4 ,it has been said of this famous doctrine of irritability that it moved all the minds of the century--and not in the departments of medicine alone--in a way of which we of the present day have no satisfactory conception1 unless we compare it with our modern ,darwinism47#a7 ,the principle of general irritability had been laid down by ,francis ,glisson 7#aeig-afgg7 from deductive studies1 but ,haller proved by experiments along the line of inductive methods that this irritability was not common to all fibre as well as to the fluids of the body1 but something entirely special1 and peculiar only to muscular substance4 ,he distinguished between irritability of muscles and sensibility of nerves4 ,in #agdg he gave as the three forces that produce muscular movements3 elasticity1 or dead nervous force2 irritability1 or innate nervous force2 and nervous force in itself4 ,and in #ageb he described one hundred and ninety experiments for determining what parts of the body possess irritability--that is1 the property of contracting when stimulated4 ,his conclusion that this irritability exists in muscular substance alone and is quite independent of the nerves proceeding to it aroused a controversy that was never definitely settled until late in the nineteenth century1 when ,haller's theory was found to be entirely correct4 ,it was in pursuit of experiments to establish his theory of irritability that ,haller made his chief discoveries in embryology and development4 ,he proved that in the process of incubation of the egg the first trace of the heart of the chick shows itself in the thirty-eighth hour1 and that the first trace of red blood showed in the forty-first hour4 ,by his investigations upon the lower animals he attempted to confirm the theory that since the creation of genus every individual is derived from a preceding individual--the existing theory of preformation1 in which he believed1 and which taught that every individual is fully and completely preformed in the germ1 simply growing from microscopic to visible proportions1 without developing any new parts4 ,in physiology1 besides his studies of the nervous system1 ,haller studied the mechanism of respiration1 refuting the teachings of ,hamberger 7#afig-agee71 who maintained that the lungs contract independently4 ,haller1 however1 in common with his contemporaries1 failed utterly to understand the true function of the lungs4 ,the great physiologist's influence upon practical medicine1 while most profound1 was largely indirect4 ,he was a theoretical rather than a practical physician1 yet he is credited with being the first physician to use the watch in counting the pulse4 ,,battista ,,morgagni ,,and ,,morbid ,,anatomy ,a great contemporary of ,haller was ,giovanni ,battista ,morgagni 7#afhb-agga71 who pursued what ,sydenham had neglected1 the investigation in anatomy1 thus supplying a necessary counterpart to the great ,englishman's work4 ,morgagni's investigations were directed chiefly to the study of morbid anatomy--the study of the structure of diseased tissue1 both during life and post mortem1 in contrast to the normal anatomical structures4 ,this work cannot be said to have originated with him2 for as early as #afgi ,bonnet had made similar1 although less extensive1 studies2 and later many investigators1 such as ,lancisi and ,haller1 had made post-mortem studies4 ,but ,morgagni's ,de sedibus et causis morborum per anatomen indagatis was the largest1 most accurate1 and best-illustrated collection of cases that had ever been brought together1 and marks an epoch in medical science4 ,from the time of the publication of ,morgagni's researches1 morbid anatomy became a recognized branch of the medical science1 and the effect of the impetus thus given it has been steadily increasing since that time4 ,,william ,,hunter ,william ,hunter 7#agah-aghc7 must always be remembered as one of the greatest physicians and anatomists of the eighteenth century1 and particularly as the first great teacher of anatomy in ,england2 but his fame has been somewhat overshadowed by that of his younger brother ,john4 ,hunter had been intended and educated for the ,church1 but on the advice of the surgeon ,william ,cullen he turned his attention to the study of medicine4 ,his first attempt at teaching was in #agdf1 when he delivered a series of lectures on surgery for the ,society of ,naval ,practitioners4 ,these lectures proved so interesting and instructive that he was at once invited to give others1 and his reputation as a lecturer was soon established4 ,he was a natural orator and story-teller1 and he combined with these attractive qualities that of thoroughness and clearness in demonstrations1 and although his lectures were two hours long he made them so full of interest that his pupils seldom tired of listening4 ,he believed that he could do greater good to the world by publicly teaching his art than by practising it1 and even during the last few days of his life1 when he was so weak that his friends remonstrated against it1 he continued his teaching1 fainting from exhaustion at the end of his last lecture1 which preceded his death by only a few days4 ,for many years it was ,hunter's ambition to establish a museum where the study of anatomy1 surgery1 and medicine might be advanced1 and in #agfe he asked for a grant of a plot of ground for this purpose1 offering to spend seven thousand pounds on its erection besides endowing it with a professorship of anatomy4 ,not being able to obtain this grant1 however1 he built a house1 in which were lecture and dissecting rooms1 and his museum4 ,in this museum were anatomical preparations1 coins1 minerals1 and natural-history specimens4 ,hunter's weakness was his love of controversy and his resentment of contradiction4 ,this brought him into strained relations with many of the leading physicians of his time1 notably his own brother ,john1 who himself was probably not entirely free from blame in the matter4 ,hunter is said to have excused his own irritability on the grounds that being an anatomist1 and accustomed to the passive submission of dead bodies1 contradictions became the more unbearable4 ,many of the physiological researches begun by him were carried on and perfected by his more famous brother1 particularly his investigations of the capillaries1 but he added much to the anatomical knowledge of several structures of the body1 notably as to the structure of cartilages and joints4 ,,john ,,hunter ,in ,abbot ,islip's chapel in ,westminster ,abbey1 close to the resting-place of ,ben ,jonson1 rest the remains of ,john ,hunter 7#agbh-agic71 famous in the annals of medicine as among the greatest physiologists and surgeons that the world has ever produced3 a man whose discoveries and inventions are counted by scores1 and whose field of research was only limited by the outermost boundaries of eighteenth-century science1 although his efforts were directed chiefly along the lines of his profession4 ,until about twenty years of age young ,hunter had shown little aptitude for study1 being unusually fond of out-door sports and amusements2 but about that time1 realizing that some occupation must be selected1 he asked permission of his brother ,william to attempt some dissections in his anatomical school in ,london4 ,to the surprise of his brother he made this dissection unusually well2 and being given a second1 he acquitted himself with such skill that his brother at once predicted that he would become a great anatomist4 ,up to this time he had had no training of any kind to prepare him for his professional career1 and knew little of ,greek or ,latin--languages entirely unnecessary for him1 as he proved in all of his life work4 ,ottley tells the story that1 when twitted with this lack of knowledge of the dead languages in after life1 he said of his opponent1 ,i could teach him that on the dead body which he never knew in any language1 dead or living4 ,by his second year in dissection he had become so skilful that he was given charge of some of the classes in his brother's school2 in #aged he became a surgeon's pupil in ,st4 ,george's ,hospital1 and two years later house-surgeon4 ,having by overwork brought on symptoms that seemed to threaten consumption1 he accepted the position of staff-surgeon to an expedition to ,belleisle in #agfj1 and two years later was serving with the ,english army at ,portugal4 ,during all this time he was constantly engaged in scientific researches1 many of which1 such as his observations of gun-shot wounds1 he put to excellent use in later life4 ,on returning to ,england much improved in health in #agfc1 he entered at once upon his career as a ,london surgeon1 and from that time forward his progress was a practically uninterrupted series of successes in his profession4 ,hunter's work on the study of the lymphatics was of great service to the medical profession4 ,this important net-work of minute vessels distributed throughout the body had recently been made the object of much study1 and various students1 including ,haller1 had made extensive investigations since their discovery by ,asellius4 ,but ,hunter1 in #ageh1 was the first to discover the lymphatics in the neck of birds1 although it was his brother ,william who advanced the theory that the function of these vessels was that of absorbents4 ,one of ,john ,hunter's pupils1 ,william ,hewson 7#agci-aggd71 first gave an account1 in #agfh1 of the lymphatics in reptiles and fishes1 and added to his teacher's investigations of the lymphatics in birds4 ,these studies of the lymphatics have been regarded1 perhaps with justice1 as ,hunter's most valuable contributions to practical medicine4 ,in #agfg he met with an accident by which he suffered a rupture of the tendo ,achillis--the large tendon that forms the attachment of the muscles of the calf to the heel4 ,from observations of this accident1 and subsequent experiments upon dogs1 he laid the foundation for the now simple and effective operation for the cure of club feet and other deformities involving the tendons4 ,in #aggb he moved into his residence at ,earlscourt1 ,brompton1 where he gathered about him a great menagerie of animals1 birds1 reptiles1 insects1 and fishes1 which he used in his physiological and surgical experiments4 ,here he performed a countless number of experiments--more1 probably1 than any man engaged in professional practice has ever conducted4 ,these experiments varied in nature from observations of the habits of bees and wasps to major surgical operations performed upon hedgehogs1 dogs1 leopards1 etc4 ,it is said that for fifteen years he kept a flock of geese for the sole purpose of studying the process of development in eggs4 ,hunter began his first course of lectures in #aggb1 being forced to do this because he had been so repeatedly misquoted1 and because he felt that he could better gauge his own knowledge in this way4 ,lecturing was a sore trial to him1 as he was extremely diffident1 and without writing out his lectures in advance he was scarcely able to speak at all4 ,in this he presented a marked contrast to his brother ,william1 who was a fluent and brilliant speaker4 ,hunter's lectures were at best simple readings of the facts as he had written them1 the diffident teacher seldom raising his eyes from his manuscript and rarely stopping until his complete lecture had been read through4 ,his lectures were1 therefore1 instructive rather than interesting1 as he used infinite care in preparing them2 but appearing before his classes was so dreaded by him that he is said to have been in the habit of taking a half-drachm of laudanum before each lecture to nerve him for the ordeal4 ,one is led to wonder by what name he shall designate that quality of mind that renders a bold and fearless surgeon like ,hunter1 who is undaunted in the face of hazardous and dangerous operations1 a stumbling1 halting1 and frightened speaker before a little band of1 at most1 thirty young medical students4 ,and yet this same thing is not unfrequently seen among the boldest surgeons4 ,hunter's ,operation for the ,cure of ,aneurisms ,it should be an object-lesson to those who1 ignorantly or otherwise1 preach against the painless vivisection as practised to-day1 that by the sacrifice of a single deer in the cause of science ,hunter discovered a fact in physiology that has been the means of saving thousands of human lives and thousands of human bodies from needless mutilation4 ,we refer to the discovery of the collateral circulation of the blood1 which led1 among other things1 to ,hunter's successful operation upon aneurisms4 ,simply stated1 every organ or muscle of the body is supplied by one large artery1 whose main trunk distributes the blood into its lesser branches1 and thence through the capillaries4 ,cutting off this main artery1 it would seem1 should cut off entirely the blood-supply to the particular organ which is supplied by this vessel2 and until the time of ,hunter's demonstration this belief was held by most physiologists4 ,but nature has made a provision for this possible stoppage of blood-supply from a single source1 and has so arranged that some of the small arterial branches coming from the main supply-trunk are connected with other arterial branches coming from some other supply-trunk4 ,under normal conditions the main arterial trunks supply their respective organs1 the little connecting arterioles playing an insignificant part4 ,but let the main supply-trunk be cut off or stopped for whatever reason1 and a remarkable thing takes place4 ,the little connecting branches begin at once to enlarge and draw blood from the neighboring uninjured supply-trunk1 ,this enlargement continues until at last a new route for the circulation has been established1 the organ no longer depending on the now defunct original arterial trunk1 but getting on as well as before by this collateral circulation that has been established4 ,the thorough understanding of this collateral circulation is one of the most important steps in surgery1 for until it was discovered amputations were thought necessary in such cases as those involving the artery supplying a leg or arm1 since it was supposed that1 the artery being stopped1 death of the limb and the subsequent necessity for amputation were sure to follow4 ,hunter solved this problem by a single operation upon a deer1 and his practicality as a surgeon led him soon after to apply this knowledge to a certain class of surgical cases in a most revolutionary and satisfactory manner4 ,what led to ,hunter's far-reaching discovery was his investigation as to the cause of the growth of the antlers of the deer4 ,wishing to ascertain just what part the blood-supply on the opposite sides of the neck played in the process of development1 or1 perhaps more correctly1 to see what effect cutting off the main blood-supply would have1 ,hunter had one of the deer of ,richmond ,park caught and tied1 while he placed a ligature around one of the carotid arteries--one of the two principal arteries that supply the head with blood4 ,he observed that shortly after this the antler 7which was only half grown and consequently very vascular7 on the side of the obliterated artery became cold to the touch--from the lack of warmth-giving blood4 ,there was nothing unexpected in this1 and ,hunter thought nothing of it until a few days later1 when he found1 to his surprise1 that the antler had become as warm as its fellow1 and was apparently increasing in size4 ,puzzled as to how this could be1 and suspecting that in some way his ligature around the artery had not been effective1 he ordered the deer killed1 and on examination was astonished to find that while his ligature had completely shut off the blood-supply from the source of that carotid artery1 the smaller arteries had become enlarged so as to supply the antler with blood as well as ever1 only by a different route4 ,hunter soon had a chance to make a practical application of the knowledge thus acquired4 ,this was a case of popliteal aneurism1 operations for which had heretofore proved pretty uniformly fatal4 ,an aneurism1 as is generally understood1 is an enlargement of a certain part of an artery1 this enlargement sometimes becoming of enormous size1 full of palpitating blood1 and likely to rupture with fatal results at any time4 ,if by any means the blood can be allowed to remain quiet for even a few hours in this aneurism it will form a clot1 contract1 and finally be absorbed and disappear without any evil results4 ,the problem of keeping the blood quiet1 with the heart continually driving it through the vessel1 is not a simple one1 and in ,hunter's time was considered so insurmountable that some surgeons advocated amputation of any member having an aneurism1 while others cut down upon the tumor itself and attempted to tie off the artery above and below4 ,the first of these operations maimed the patient for life1 while the second was likely to prove fatal4 ,in pondering over what he had learned about collateral circulation and the time required for it to become fully established1 ,hunter conceived the idea that if the blood-supply was cut off from above the aneurism1 thus temporarily preventing the ceaseless pulsations from the heart1 this blood would coagulate and form a clot before the collateral circulation could become established or could affect it4 ,the patient upon whom he performed his now celebrated operation was afflicted with a popliteal aneurism--that is1 the aneurism was located on the large popliteal artery just behind the knee-joint4 ,hunter1 therefore1 tied off the femoral1 or main supplying artery in the thigh1 a little distance above the aneurism4 ,the operation was entirely successful1 and in six weeks' time the patient was able to leave the hospital1 and with two sound limbs4 ,naturally the simplicity and success of this operation aroused the attention of ,europe1 and1 alone1 would have made the name of ,hunter immortal in the annals of surgery4 ,the operation has ever since been called the ,hunterian operation for aneurism1 but there is reason to believe that ,dominique ,anel 7born about #afgi7 performed a somewhat similar operation several years earlier4 ,it is probable1 however1 that ,hunter had never heard of this work of ,anel1 and that his operation was the outcome of his own independent reasoning from the facts he had learned about collateral circulation4 ,furthermore1 ,hunter's mode of operation was a much better one than ,anel's1 and1 while ,anel's must claim priority1 the credit of making it widely known will always be ,hunter's4 ,the great services of ,hunter were recognized both at home and abroad1 and honors and positions of honor and responsibility were given him4 ,in #aggf he was appointed surgeon-extraordinary to the king2 in #aghc he was elected a member of the ,royal ,society of ,medicine and of the ,royal ,academy of ,surgery at ,paris2 in #aghf he became deputy surgeon-general of the army2 and in #agij he was appointed surgeon-general and inspector-general of hospitals4 ,all these positions he filled with credit1 and he was actively engaged in his tireless pursuit of knowledge and in discharging his many duties when in ,october1 #agic1 he was stricken while addressing some colleagues1 and fell dead in the arms of a fellow-physician4 ,,lazzaro ,,spallanzani ,hunter's great rival among contemporary physiologists was the ,italian ,lazzaro ,spallanzani 7#agbi-agii71 one of the most picturesque figures in the history of science4 ,he was not educated either as a scientist or physician1 devoting1 himself at first to philosophy and the languages1 afterwards studying law1 and later taking orders4 ,but he was a keen observer of nature and of a questioning and investigating mind1 so that he is remembered now chiefly for his discoveries and investigations in the biological sciences4 ,one important demonstration was his controversion of the theory of abiogenesis1 or spontaneous generation1 as propounded by ,needham and ,buffon4 ,at the time of ,needham's experiments it had long been observed that when animal or vegetable matter had lain in water for a little time--long enough for it to begin to undergo decomposition--the water became filled with microscopic creatures1 the infusoria animalculis4 ,this would tend to show1 either that the water or the animal or vegetable substance contained the germs of these minute organisms1 or else that they were generated spontaneously4 ,it was known that boiling killed these animalcules1 and ,needham agreed1 therefore1 that if he first heated the meat or vegetables1 and also the water containing them1 and then placed them in hermetically scaled jars--if he did this1 and still the animalcules made their appearance1 it would be proof-positive that they had been generated spontaneously4 ,accordingly he made numerous experiments1 always with the same results--that after a few days the water was found to swarm with the microscopic creatures4 ,the thing seemed proven beyond question--providing1 of course1 that there had been no slips in the experiments4 ,but ,abbe ,spallanzani thought that he detected such slips in ,needham's experiment4 ,the possibility of such slips might come in several ways3 the contents of the jar might not have been boiled for a sufficient length of time to kill all the germs1 or the air might not have been excluded completely by the sealing process4 ,to cover both these contingencies1 ,spallanzani first hermetically sealed the glass vessels and then boiled them for three-quarters of an hour4 ,under these circumstances no animalcules ever made their appearance--a conclusive demonstration that rendered ,needham's grounds for his theory at once untenable47#b7 ,allied to these studies of spontaneous generation were ,spallanzani's experiments and observations on the physiological processes of generation among higher animals4 ,he experimented with frogs1 tortoises1 and dogs2 and settled beyond question the function of the ovum and spermatozoon4 ,unfortunately he misinterpreted the part played by the spermatozoa in believing that their surrounding fluid was equally active in the fertilizing process1 and it was not until some forty years later 7#ahbd7 that ,dumas corrected this error4 ,,the ,,chemical ,,theory ,,of ,,digestion ,among the most interesting researches of ,spallanzani were his experiments to prove that digestion1 as carried on in the stomach1 is a chemical process4 ,in this he demonstrated1 as ,rene ,reaumur had attempted to demonstrate1 that digestion could be carried on outside the walls of the stomach as an ordinary chemical reaction1 using the gastric juice as the reagent for performing the experiment4 ,the question as to whether the stomach acted as a grinding or triturating organ1 rather than as a receptacle for chemical action1 had been settled by ,reaumur and was no longer a question of general dispute4 ,reaumur had demonstrated conclusively that digestion would take place in the stomach in the same manner and the same time if the substance to be digested was protected from the peristalic movements of the stomach and subjected to the action of the gastric juice only4 ,he did this by introducing the substances to be digested into the stomach in tubes1 and thus protected so that while the juices of the stomach could act upon them freely they would not be affected by any movements of the organ4 ,following up these experiments1 he attempted to show that digestion could take place outside the body as well as in it1 as it certainly should if it were a purely chemical process4 ,he collected quantities of gastric juice1 and placing it in suitable vessels containing crushed grain or flesh1 kept the mixture at about the temperature of the body for several hours4 ,after repeated experiments of this kind1 apparently conducted with great care1 ,reaumur reached the conclusion that the gastric juice has no more effect out of the living body in dissolving or digesting the food than water1 mucilage1 milk1 or any other bland fluid47#c7 ,just why all of these experiments failed to demonstrate a fact so simple does not appear2 but to ,spallanzani1 at least1 they were by no means conclusive1 and he proceeded to elaborate upon the experiments of ,reaumur4 ,he made his experiments in scaled tubes exposed to a certain degree of heat1 and showed conclusively that the chemical process does go on1 even when the food and gastric juice are removed from their natural environment in the stomach4 ,in this he was opposed by many physiologists1 among them ,john ,hunter1 but the truth of his demonstrations could not be shaken1 and in later years we find ,hunter himself completing ,spallanzani's experiments by his studies of the post-mortem action of the gastric juice upon the stomach walls4 ,that ,spallanzani's and ,hunter's theories of the action of the gastric juice were not at once universally accepted is shown by an essay written by a learned physician in #ahcd4 ,in speaking of some of ,spallanzani's demonstrations1 he writes3 ,in some of the experiments1 in order to give the flesh or grains steeped in the gastric juice the same temperature with the body1 the phials were introduced under the armpits4 ,but this is not a fair mode of ascertaining the effects of the gastric juice out of the body2 for the influence which life may be supposed to have on the solution of the food would be secured in this case4 ,the affinities connected with life would extend to substances in contact with any part of the system3 substances placed under the armpits are not placed at least in the same circumstances with those unconnected with a living animal4 ,but just how this writer reaches the conclusion that the experiments of ,reaumur and ,spallanzani give no evidence that the gastric juice has any peculiar influence more than water or any other bland fluid in digesting the food7#d7 is difficult to understand4 ,the concluding touches were given to the new theory of digestion by ,john ,hunter1 who1 as we have seen1 at first opposed ,spallanzani1 but who finally became an ardent champion of the chemical theory4 ,hunter now carried ,spallanzani's experiments further and proved the action of the digestive fluids after death4 ,for many years anatomists had been puzzled by pathological lesion of the stomach1 found post mortem1 when no symptoms of any disorder of the stomach had been evinced during life4 ,hunter rightly conceived that these lesions were caused by the action of the gastric juice1 which1 while unable to act upon the living tissue1 continued its action chemically after death1 thus digesting the walls of the stomach in which it had been formed4 ,and1 as usual with his observations1 he turned this discovery to practical use in accounting for certain phenomena of digestion4 ,the following account of the stomach being digested after death was written by ,hunter at the desire of ,sir ,john ,pringle1 when he was president of the ,royal ,society1 and the circumstance which led to this is as follows3 ,i was opening1 in his presence1 the body of a patient of his own1 where the stomach was in part dissolved1 which appeared to him very unaccountable1 as there had been no previous symptom that could have led him to suspect any disease in the stomach4 ,i took that opportunity of giving him my ideas respecting it1 and told him that ,i had long been making experiments on digestion1 and considered this as one of the facts which proved a converting power in the gastric juice4444 ,there are a great many powers in nature which the living principle does not enable the animal matter1 with which it is combined1 to resist--viz41 the mechanical and most of the strongest chemical solvents4 ,it renders it1 however1 capable of resisting the powers of fermentation1 digestion1 and perhaps several others1 which are well known to act on the same matter when deprived of the living principle and entirely to decompose it4 ,hunter concludes his paper with the following paragraph3 ,these appearances throw considerable light on the principle of digestion1 and show that it is neither a mechanical power1 nor contractions of the stomach1 nor heat1 but something secreted in the coats of the stomach1 and thrown into its cavity1 which there animalizes the food or assimilates it to the nature of the blood4 ,the power of this juice is confined or limited to certain substances1 especially of the vegetable and animal kingdoms2 and although this menstruum is capable of acting independently of the stomach1 yet it is indebted to that viscus for its continuance47#e7 ,,the ,,function ,,of ,,respiration ,it is a curious commentary on the crude notions of mechanics of previous generations that it should have been necessary to prove by experiment that the thin1 almost membranous stomach of a mammal has not the power to pulverize1 by mere attrition1 the foods that are taken into it4 ,however1 the proof was now for the first time forthcoming1 and the question of the general character of the function of digestion was forever set at rest4 ,almost simultaneously with this great advance1 corresponding progress was made in an allied field3 the mysteries of respiration were at last cleared up1 thanks to the new knowledge of chemistry4 ,the solution of the problem followed almost as a matter of course upon the advances of that science in the latter part of the century4 ,hitherto no one since ,mayow1 of the previous century1 whose flash of insight had been strangely overlooked and forgotten1 had even vaguely surmised the true function of the lungs4 ,the great ,boerhaave had supposed that respiration is chiefly important as an aid to the circulation of the blood2 his great pupil1 ,haller1 had believed to the day of his death in #aggg that the main purpose of the function is to form the voice4 ,no genius could hope to fathom the mystery of the lungs so long as air was supposed to be a simple element1 serving a mere mechanical purpose in the economy of the earth4 ,but the discovery of oxygen gave the clew1 and very soon all the chemists were testing the air that came from the lungs--,dr4 ,priestley1 as usual1 being in the van4 ,his initial experiments were made in #aggg1 and from the outset the problem was as good as solved4 ,other experimenters confirmed his results in all their essentials--notably ,scheele and ,lavoisier and ,spallanzani and ,davy4 ,it was clearly established that there is chemical action in the contact of the air with the tissue of the lungs2 that some of the oxygen of the air disappears1 and that carbonic-acid gas is added to the inspired air4 ,it was shown1 too1 that the blood1 having come in contact with the air1 is changed from black to red in color4 ,these essentials were not in dispute from the first4 ,but as to just what chemical changes caused these results was the subject of controversy4 ,whether1 for example1 oxygen is actually absorbed into the blood1 or whether it merely unites with carbon given off from the blood1 was long in dispute4 ,each of the main disputants was biased by his own particular views as to the moot points of chemistry4 ,lavoisier1 for example1 believed oxygen gas to be composed of a metal oxygen combined with the alleged element heat2 ,dr4 ,priestley thought it a compound of positive electricity and phlogiston2 and ,humphry ,davy1 when he entered the lists a little later1 supposed it to be a compound of oxygen and light4 ,such mistaken notions naturally complicated matters and delayed a complete understanding of the chemical processes of respiration4 ,it was some time1 too1 before the idea gained acceptance that the most important chemical changes do not occur in the lungs themselves1 but in the ultimate tissues4 ,indeed1 the matter was not clearly settled at the close of the century4 ,nevertheless1 the problem of respiration had been solved in its essentials4 ,moreover1 the vastly important fact had been established that a process essentially identical with respiration is necessary to the existence not only of all creatures supplied with lungs1 but to fishes1 insects1 and even vegetables--in short1 to every kind of living organism4 ,,erasmus ,,darwin ,,and ,,vegetable ,,physiology ,some interesting experiments regarding vegetable respiration were made just at the close of the century by ,erasmus ,darwin1 and recorded in his ,botanic ,garden as a foot-note to the verse3 ,while spread in air the leaves respiring play4 ,these notes are worth quoting at some length1 as they give a clear idea of the physiological doctrines of the time 7#agii71 while taking advance ground as to the specific matter in question3 ,there have been various opinions1 ,darwin says1 concerning the use of the leaves of plants in the vegetable economy4 ,some have contended that they are perspiratory organs4 ,this does not seem probable from an experiment of ,dr4 ,hales1 ,vegetable ,statics1 p4 #cj4 ,he1 found1 by cutting off branches of trees with apples on them and taking off the leaves1 that an apple exhaled about as much as two leaves the surfaces of which were nearly equal to the apple2 whence it would appear that apples have as good a claim to be termed perspiratory organs as leaves4 ,others have believed them excretory organs of excrementitious juices1 but as the vapor exhaled from vegetables has no taste1 this idea is no more probable than the other2 add to this that in most weathers they do not appear to perspire or exhale at all4 ,the internal surface of the lungs or air-vessels in men is said to be equal to the external surface of the whole body1 or almost fifteen square feet2 on this surface the blood is exposed to the influence of the respired air through the medium1 however1 of a thin pellicle2 by this exposure to the air it has its color changed from deep red to bright scarlet1 and acquires something so necessary to the existence of life that we can live scarcely a minute without this wonderful process4 ,the analogy between the leaves of plants and the lungs or gills of animals seems to embrace so many circumstances that we can scarcely withhold our consent to their performing similar offices4 #a4 ,the great surface of leaves compared to that of the trunk and branches of trees is such that it would seem to be an organ well adapted for the purpose of exposing the vegetable juices to the influence of the air2 this1 however1 we shall see afterwards is probably performed only by their upper surfaces1 yet even in this case the surface of the leaves in general bear a greater proportion to the surface of the tree than the lungs of animals to their external surfaces4 #b4 ,in the lung of animals the blood1 after having been exposed to the air in the extremities of the pulmonary artery1 is changed in color from deep red to bright scarlet1 and certainly in some of its essential properties it is then collected by the pulmonary vein and returned to the heart4 ,to show a similarity of circumstances in the leaves of plants1 the following experiment was made1 ,june #bd1 #agha4 ,a stalk with leaves and seed-vessels of large spurge 7,euphorbia helioscopia7 had been several days placed in a decoction of madder 7,rubia tinctorum7 so that the lower part of the stem and two of the undermost leaves were immersed in it4 ,after having washed the immersed leaves in clear water ,i could readily discover the color of the madder passing along the middle rib of each leaf4 ,the red artery was beautifully visible on the under and on the upper surface of the leaf2 but on the upper side many red branches were seen going from it to the extremities of the leaf1 which on the other side were not visible except by looking through it against the light4 ,on this under side a system of branching vessels carrying a pale milky fluid were seen coming from the extremities of the leaf1 and covering the whole under side of it1 and joining two large veins1 one on each side of the red artery in the middle rib of the leaf1 and along with it descending to the foot-stalk or petiole4 ,on slitting one of these leaves with scissors1 and having a magnifying-glass ready1 the milky blood was seen oozing out of the returning veins on each side of the red artery in the middle rib1 but none of the red fluid from the artery4 ,all these appearances were more easily seen in a leaf of ,picris treated in the same manner2 for in this milky plant the stems and middle rib of the leaves are sometimes naturally colored reddish1 and hence the color of the madder seemed to pass farther into the ramifications of their leaf-arteries1 and was there beautifully visible with the returning branches of milky veins on each side4 ,darwin now goes on to draw an incorrect inference from his observations3 #c4 ,from these experiments1 he says1 the upper surface of the leaf appeared to be the immediate organ of respiration1 because the colored fluid was carried to the extremities of the leaf by vessels most conspicuous on the upper surface1 and there changed into a milky fluid1 which is the blood of the plant1 and then returned by concomitant veins on the under surface1 which were seen to ooze when divided with scissors1 and which1 in ,picris1 particularly1 render the under surface of the leaves greatly whiter than the upper one4 ,but in point of fact1 as studies of a later generation were to show1 it is the under surface of the leaf that is most abundantly provided with stomata1 or breathing-pores4 ,from the stand-point of this later knowledge1 it is of interest to follow our author a little farther1 to illustrate yet more fully the possibility of combining correct observations with a faulty inference4 #d4 ,as the upper surface of leaves constitutes the organ of respiration1 on which the sap is exposed in the termination of arteries beneath a thin pellicle to the action of the atmosphere1 these surfaces in many plants strongly repel moisture1 as cabbage leaves1 whence the particles of rain lying over their surfaces without touching them1 as observed by ,mr4 ,melville 7,essays ,literary and ,philosophical3 ,edinburgh71 have the appearance of globules of quicksilver4 ,and hence leaves with the upper surfaces on water wither as soon as in the dry air1 but continue green for many days if placed with the under surface on water1 as appears in the experiments of ,monsieur ,bonnet 7,usage des ,feuilles74 ,hence some aquatic plants1 as the water-lily 7,nymphoea71 have the lower sides floating on the water1 while the upper surfaces remain dry in the air4 #e4 ,as those insects which have many spiracula1 or breathing apertures1 as wasps and flies1 are immediately suffocated by pouring oil upon them1 ,i carefully covered with oil the surfaces of several leaves of phlomis1 of ,portugal laurel1 and balsams1 and though it would not regularly adhere1 ,i found them all die in a day or two4 ,it must be added that many leaves are furnished with muscles about their foot-stalks1 to turn their surfaces to the air or light1 as mimosa or ,hedysarum gyrans4 ,from all these analogies ,i think there can be no doubt but that leaves of trees are their lungs1 giving out a phlogistic material to the atmosphere1 and absorbing oxygen1 or vital air4 #f4 ,the great use of light to vegetation would appear from this theory to be by disengaging vital air from the water which they perspire1 and thence to facilitate its union with their blood exposed beneath the thin surface of their leaves2 since when pure air is thus applied it is probable that it can be more readily absorbed4 ,hence1 in the curious experiments of ,dr4 ,priestley and ,mr4 ,ingenhouz1 some plants purified less air than others--that is1 they perspired less in the sunshine2 and ,mr4 ,scheele found that by putting peas into water which about half covered them they converted the vital air into fixed air1 or carbonic-acid gas1 in the same manner as in animal respiration4 #g4 ,the circulation in the lungs or leaves of plants is very similar to that of fish4 ,in fish the blood1 after having passed through their gills1 does not return to the heart as from the lungs of air-breathing animals1 but the pulmonary vein taking the structure of an artery after having received the blood from the gills1 which there gains a more florid color1 distributes it to the other parts of their bodies4 ,the same structure occurs in the livers of fish1 whence we see in those animals two circulations independent of the power of the heart--viz41 that beginning at the termination of the veins of the gills and branching through the muscles1 and that which passes through the liver2 both which are carried on by the action of those respective arteries and veins47#f7 ,darwin is here a trifle fanciful in forcing the analogy between plants and animals4 ,the circulatory system of plants is really not quite so elaborately comparable to that of fishes as he supposed4 ,but the all-important idea of the uniformity underlying the seeming diversity of ,nature is here exemplified1 as elsewhere in the writings of ,erasmus ,darwin2 and1 more specifically1 a clear grasp of the essentials of the function of respiration is fully demonstrated4 ,,zoology ,,at ,,the ,,close ,,of ,,the ,,eighteenth ,,century ,several causes conspired to make exploration all the fashion during the closing epoch of the eighteenth century4 ,new aid to the navigator had been furnished by the perfected compass and quadrant1 and by the invention of the chronometer2 medical science had banished scurvy1 which hitherto had been a perpetual menace to the voyager2 and1 above all1 the restless spirit of the age impelled the venturesome to seek novelty in fields altogether new4 ,some started for the pole1 others tried for a northeast or northwest passage to ,india1 yet others sought the great fictitious antarctic continent told of by tradition4 ,all these of course failed of their immediate purpose1 but they added much to the world's store of knowledge and its fund of travellers' tales4 ,among all these tales none was more remarkable than those which told of strange living creatures found in antipodal lands4 ,and here1 as did not happen in every field1 the narratives were often substantiated by the exhibition of specimens that admitted no question4 ,many a company of explorers returned more or less laden with such trophies from the animal and vegetable kingdoms1 to the mingled astonishment1 delight1 and bewilderment of the closet naturalists4 ,the followers of ,linnaeus in the golden age of natural history1 a few decades before1 had increased the number of known species of fishes to about four hundred1 of birds to one thousand1 of insects to three thousand1 and of plants to ten thousand4 ,but now these sudden accessions from new territories doubled the figure for plants1 tripled it for fish and birds1 and brought the number of described insects above twenty thousand4 ,naturally enough1 this wealth of new material was sorely puzzling to the classifiers4 ,the more discerning began to see that the artificial system of ,linnaeus1 wonderful and useful as it had been1 must be advanced upon before the new material could be satisfactorily disposed of4 ,the way to a more natural system1 based on less arbitrary signs1 had been pointed out by ,jussieu in botany1 but the zoologists were not prepared to make headway towards such a system until they should gain a wider understanding of the organisms with which they had to deal through comprehensive studies of anatomy4 ,such studies of individual forms in their relations to the entire scale of organic beings were pursued in these last decades of the century1 but though two or three most important generalizations were achieved 7notably ,kaspar ,wolff's conception of the cell as the basis of organic life1 and ,goethe's all-important doctrine of metamorphosis of parts71 yet1 as a whole1 the work of the anatomists of the period was germinative rather than fruit-bearing4 ,bichat's volumes1 telling of the recognition of the fundamental tissues of the body1 did not begin to appear till the last year of the century4 ,the announcement by ,cuvier of the doctrine of correlation of parts bears the same date1 but in general the studies of this great naturalist1 which in due time were to stamp him as the successor of ,linnaeus1 were as yet only fairly begun4 ,v4 ,,anatomy ,,and ,,physiology ,,in ,,the ,,nineteenth ,,century ,,cuvier ,,and ,,the ,,correlation ,,of ,,parts ,we have seen that the focal points of the physiological world towards the close of the eighteenth century were ,italy and ,england1 but when ,spallanzani and ,hunter passed away the scene shifted to ,france4 ,the time was peculiarly propitious1 as the recent advances in many lines of science had brought fresh data for the student of animal life which were in need of classification1 and1 as several minds capable of such a task were in the field1 it was natural that great generalizations should have come to be quite the fashion4 ,thus it was that ,cuvier came forward with a brand-new classification of the animal kingdom1 establishing four great types of being1 which he called vertebrates1 mollusks1 articulates1 and radiates4 ,lamarck had shortly before established the broad distinction between animals with and those without a backbone2 ,cuvier's ,classification divided the latter--the invertebrates--into three minor groups4 ,and this division1 familiar ever since to all students of zoology1 has only in very recent years been supplanted1 and then not by revolution1 but by a further division1 which the elaborate recent studies of lower forms of life seemed to make desirable4 ,in the course of those studies of comparative anatomy which led to his new classification1 ,cuvier's attention was called constantly to the peculiar co-ordination of parts in each individual organism4 ,thus an animal with sharp talons for catching living prey--as a member of the cat tribe--has also sharp teeth1 adapted for tearing up the flesh of its victim1 and a particular type of stomach1 quite different from that of herbivorous creatures4 ,this adaptation of all the parts of the animal to one another extends to the most diverse parts of the organism1 and enables the skilled anatomist1 from the observation of a single typical part1 to draw inferences as to the structure of the entire animal--a fact which was of vast aid to ,cuvier in his studies of paleontology4 ,it did not enable ,cuvier1 nor does it enable any one else1 to reconstruct fully the extinct animal from observation of a single bone1 as has sometimes been asserted1 but what it really does establish1 in the hands of an expert1 is sufficiently astonishing4 ,while the study of the fossil remains of the greater quadrupeds is more satisfactory1 he writes1 by the clear results which it affords1 than that of the remains of other animals found in a fossil state1 it is also complicated with greater and more numerous difficulties4 ,fossil shells are usually found quite entire1 and retaining all the characters requisite for comparing them with the specimens contained in collections of natural history1 or represented in the works of naturalists4 ,even the skeletons of fishes are found more or less entire1 so that the general forms of their bodies can1 for the most part1 be ascertained1 and usually1 at least1 their generic and specific characters are determinable1 as these are mostly drawn from their solid parts4 ,in quadrupeds1 on the contrary1 even when their entire skeletons are found1 there is great difficulty in discovering their distinguishing characters1 as these are chiefly founded upon their hairs and colors and other marks which have disappeared previous to their incrustation4 ,it is also very rare to find any fossil skeletons of quadrupeds in any degree approaching to a complete state1 as the strata for the most part only contain separate bones1 scattered confusedly and almost always broken and reduced to fragments1 which are the only means left to naturalists for ascertaining the species or genera to which they have belonged4 ,fortunately comparative anatomy1 when thoroughly understood1 enables us to surmount all these difficulties1 as a careful application of its principles instructs us in the correspondences and dissimilarities of the forms of organized bodies of different kinds1 by which each may be rigorously ascertained from almost every fragment of its various parts and organs4 ,every organized individual forms an entire system of its own1 all the parts of which naturally correspond1 and concur to produce a certain definite purpose1 by reciprocal reaction1 or by combining towards the same end4 ,hence none of these separate parts can change their forms without a corresponding change in the other parts of the same animal1 and consequently each of these parts1 taken separately1 indicates all the other parts to which it has belonged4 ,thus1 as ,i have elsewhere shown1 if the viscera of an animal are so organized as only to be fitted for the digestion of recent flesh1 it is also requisite that the jaws should be so constructed as to fit them for devouring prey2 the claws must be constructed for seizing and tearing it to pieces2 the teeth for cutting and dividing its flesh2 the entire system of the limbs1 or organs of motion1 for pursuing and overtaking it2 and the organs of sense for discovering it at a distance4 ,nature must also have endowed the brain of the animal with instincts sufficient for concealing itself and for laying plans to catch its necessary victims4444 ,to enable the animal to carry off its prey when seized1 a corresponding force is requisite in the muscles which elevate the head1 and this necessarily gives rise to a determinate form of the vertebrae to which these muscles are attached and of the occiput into which they are inserted4 ,in order that the teeth of a carnivorous animal may be able to cut the flesh1 they require to be sharp1 more or less so in proportion to the greater or less quantity of flesh that they have to cut4 ,it is requisite that their roots should be solid and strong1 in proportion to the quantity and size of the bones which they have to break to pieces4 ,the whole of these circumstances must necessarily influence the development and form of all the parts which contribute to move the jaws4444 ,after these observations1 it will be easily seen that similar conclusions may be drawn with respect to the limbs of carnivorous animals1 which require particular conformations to fit them for rapidity of motion in general2 and that similar considerations must influence the forms and connections of the vertebrae and other bones constituting the trunk of the body1 to fit them for flexibility and readiness of motion in all directions4 ,the bones also of the nose1 of the orbit1 and of the ears require certain forms and structures to fit them for giving perfection to the senses of smell1 sight1 and hearing1 so necessary to animals of prey4 ,in short1 the shape and structure of the teeth regulate the forms of the condyle1 of the shoulder-blade1 and of the claws1 in the same manner as the equation of a curve regulates all its other properties2 and as in regard to any particular curve all its properties may be ascertained by assuming each separate property as the foundation of a particular equation1 in the same manner a claw1 a shoulder-blade1 a condyle1 a leg or arm bone1 or any other bone separately considered1 enables us to discover the description of teeth to which they have belonged2 and so also reciprocally we may determine the forms of the other bones from the teeth4 ,thus commencing our investigations by a careful survey of any one bone by itself1 a person who is sufficiently master of the laws of organic structure may1 as it were1 reconstruct the whole animal to which that bone belonged47#a7 ,we have already pointed out that no one is quite able to perform the necromantic feat suggested in the last sentence2 but the exaggeration is pardonable in the enthusiast to whom the principle meant so much and in whose hands it extended so far4 ,of course this entire principle1 in its broad outlines1 is something with which every student of anatomy had been familiar from the time when anatomy was first studied1 but the full expression of the law of co-ordination1 as ,cuvier called it1 had never been explicitly made before2 and1 notwithstanding its seeming obviousness1 the exposition which ,cuvier made of it in the introduction to his classical work on comparative anatomy1 which was published during the first decade of the nineteenth century1 ranks as a great discovery4 ,it is one of those generalizations which serve as guideposts to other discoveries4 ,,bichat ,,and ,,the ,,bodily ,,tissues ,much the same thing may be said of another generalization regarding the animal body1 which the brilliant young ,french physician ,marie ,francois ,bichat made in calling attention to the fact that each vertebrate organism1 including man1 has really two quite different sets of organs--one set under volitional control1 and serving the end of locomotion1 the other removed from volitional control1 and serving the ends of the vital processes of digestion1 assimilation1 and the like4 ,he called these sets of organs the animal system and the organic system1 respectively4 ,the division thus pointed out was not quite new1 for ,grimaud1 professor of physiology in the ,university of ,montpellier1 had earlier made what was substantially the same classification of the functions into internal or digestive and external or locomotive2 but it was ,bichat's exposition that gave currency to the idea4 ,far more important1 however1 was another classification which ,bichat put forward in his work on anatomy1 published just at the beginning of the last century4 ,this was the division of all animal structures into what ,bichat called tissues1 and the pointing out that there are really only a few kinds of these in the body1 making up all the diverse organs4 ,thus muscular organs form one system2 membranous organs another2 glandular organs a third2 the vascular mechanism a fourth1 and so on4 ,the distinction is so obvious that it seems rather difficult to conceive that it could have been overlooked by the earliest anatomists2 but1 in point of fact1 it is only obvious because now it has been familiarly taught for almost a century4 ,it had never been given explicit expression before the time of ,bichat1 though it is said that ,bichat himself was somewhat indebted for it to his master1 ,desault1 and to the famous alienist ,pinel4 ,however that may be1 it is certain that all subsequent anatomists have found ,bichat's classification of the tissues of the utmost value in their studies of the animal functions4 ,subsequent advances were to show that the distinction between the various tissues is not really so fundamental as ,bichat supposed1 but that takes nothing from the practical value of the famous classification4 ,it was but a step from this scientific classification of tissues to a similar classification of the diseases affecting them1 and this was one of the greatest steps towards placing medicine on the plane of an exact science4 ,this subject of these branches completely fascinated ,bichat1 and he exclaimed1 enthusiastically3 ,take away some fevers and nervous trouble1 and all else belongs to the kingdom of pathological anatomy4 ,but out of this enthusiasm came great results4 ,bichat practised as he preached1 and1 believing that it was only possible to understand disease by observing the symptoms carefully at the bedside1 and1 if the disease terminated fatally1 by post-mortem examination1 he was so arduous in his pursuit of knowledge that within a period of less than six months he had made over six hundred autopsies--a record that has seldom1 if ever1 been equalled4 ,nor were his efforts fruitless1 as a single example will suffice to show4 ,by his examinations he was able to prove that diseases of the chest1 which had formerly been classed under the indefinite name peripneumonia1 might involve three different structures1 the pleural sac covering the lungs1 the lung itself1 and the bronchial tubes1 the diseases affecting these organs being known respectively as pleuritis1 pneumonia1 and bronchitis1 each one differing from the others as to prognosis and treatment4 ,the advantage of such an exact classification needs no demonstration4 ,,lister ,,and ,,the ,,perfected ,,microscope ,at the same time when these broad macroscopical distinctions were being drawn there were other workers who were striving to go even deeper into the intricacies of the animal mechanism with the aid of the microscope4 ,this undertaking1 however1 was beset with very great optical difficulties1 and for a long time little advance was made upon the work of preceding generations4 ,two great optical barriers1 known technically as spherical and chromatic aberration--the one due to a failure of the rays of light to fall all in one plane when focalized through a lens1 the other due to the dispersive action of the lens in breaking the white light into prismatic colors--confronted the makers of microscopic lenses1 and seemed all but insuperable4 ,the making of achromatic lenses for telescopes had been accomplished1 it is true1 by ,dolland in the previous century1 by the union of lenses of crown glass with those of flint glass1 these two materials having different indices of refraction and dispersion4 ,but1 aside from the mechanical difficulties which arise when the lens is of the minute dimensions required for use with the microscope1 other perplexities are introduced by the fact that the use of a wide pencil of light is a desideratum1 in order to gain sufficient illumination when large magnification is to be secured4 ,in the attempt to overcome those difficulties1 the foremost physical philosophers of the time came to the aid of the best opticians4 ,very early in the century1 ,dr4 7afterwards ,sir ,david7 ,brewster1 the renowned ,scotch physicist1 suggested that certain advantages might accrue from the use of such gems as have high refractive and low dispersive indices1 in place of lenses made of glass4 ,accordingly lenses were made of diamond1 of sapphire1 and so on1 and with some measure of success4 ,but in #ahab a much more important innovation was introduced by ,dr4 ,william ,hyde ,wollaston1 one of the greatest and most versatile1 and1 since the death of ,cavendish1 by far the most eccentric of ,english natural philosophers4 ,this was the suggestion to use two plano-convex lenses1 placed at a prescribed distance apart1 in lieu of the single double-convex lens generally used4 ,this combination largely overcame the spherical aberration1 and it gained immediate fame as the ,wollaston doublet4 ,to obviate loss of light in such a doublet from increase of reflecting surfaces1 ,dr4 ,brewster suggested filling the interspace between the two lenses with a cement having the same index of refraction as the lenses themselves--an improvement of manifest advantage4 ,an improvement yet more important was made by ,dr4 ,wollaston himself in the introduction of the diaphragm to limit the field of vision between the lenses1 instead of in front of the anterior lens4 ,a pair of lenses thus equipped ,dr4 ,wollaston called the periscopic microscope4 ,dr4 ,brewster suggested that in such a lens the same object might be attained with greater ease by grinding an equatorial groove about a thick or globular lens and filling the groove with an opaque cement4 ,this arrangement found much favor1 and came subsequently to be known as a ,coddington lens1 though ,mr4 ,coddington laid no claim to being its inventor4 ,sir ,john ,herschel1 another of the very great physicists of the time1 also gave attention to the problem of improving the microscope1 and in #ahba he introduced what was called an aplanatic combination of lenses1 in which1 as the name implies1 the spherical aberration was largely done away with4 ,it was thought that the use of this ,herschel aplanatic combination as an eyepiece1 combined with the ,wollaston doublet for the objective1 came as near perfection as the compound microscope was likely soon to come4 ,but in reality the instrument thus constructed1 though doubtless superior to any predecessor1 was so defective that for practical purposes the simple microscope1 such as the doublet or the ,coddington1 was preferable to the more complicated one4 ,many opticians1 indeed1 quite despaired of ever being able to make a satisfactory refracting compound microscope1 and some of them had taken up anew ,sir ,isaac ,newton's suggestion in reference to a reflecting microscope4 ,in particular1 ,professor ,giovanni ,battista ,amici1 a very famous mathematician and practical optician of ,modena1 succeeded in constructing a reflecting microscope which was said to be superior to any compound microscope of the time1 though the events of the ensuing years were destined to rob it of all but historical value4 ,for there were others1 fortunately1 who did not despair of the possibilities of the refracting microscope1 and their efforts were destined before long to be crowned with a degree of success not even dreamed of by any preceding generation4 ,the man to whom chief credit is due for directing those final steps that made the compound microscope a practical implement instead of a scientific toy was the ,english amateur optician ,joseph ,jackson ,lister4 ,combining mathematical knowledge with mechanical ingenuity1 and having the practical aid of the celebrated optician ,tulley1 he devised formulae for the combination of lenses of crown glass with others of flint glass1 so adjusted that the refractive errors of one were corrected or compensated by the other1 with the result of producing lenses of hitherto unequalled powers of definition2 lenses capable of showing an image highly magnified1 yet relatively free from those distortions and fringes of color that had heretofore been so disastrous to true interpretation of magnified structures4 ,lister had begun his studies of the lens in #ahbd1 but it was not until #ahcj that he contributed to the ,royal ,society the famous paper detailing his theories and experiments4 ,soon after this various continental opticians who had long been working along similar lines took the matter up1 and their expositions1 in particular that of ,amici1 introduced the improved compound microscope to the attention of microscopists everywhere4 ,and it required but the most casual trial to convince the experienced observers that a new implement of scientific research had been placed in their hands which carried them a long step nearer the observation of the intimate physical processes which lie at the foundation of vital phenomena4 ,for the physiologist this perfection of the compound microscope had the same significance that the1 discovery of ,america had for the fifteenth-century geographers--it promised a veritable world of utterly novel revelations4 ,nor was the fulfilment of that promise long delayed4 ,indeed1 so numerous and so important were the discoveries now made in the realm of minute anatomy that the rise of histology to the rank of an independent science may be said to date from this period4 ,hitherto1 ever since the discovery of magnifying-glasses1 there had been here and there a man1 such as ,leuwenhoek or ,malpighi1 gifted with exceptional vision1 and perhaps unusually happy in his conjectures1 who made important contributions to the knowledge of the minute structure of organic tissues2 but now of a sudden it became possible for the veriest tyro to confirm or refute the laborious observations of these pioneers1 while the skilled observer could step easily beyond the barriers of vision that hitherto were quite impassable4 ,and so1 naturally enough1 the physiologists of the fourth decade of the nineteenth century rushed as eagerly into the new realm of the microscope as1 for example1 their successors of to-day are exploring the realm of the ,x-ray4 ,lister himself1 who had become an eager interrogator of the instrument he had perfected1 made many important discoveries1 the most notable being his final settlement of the long-mooted question as to the true form of the red corpuscles of the human blood4 ,in reality1 as everybody knows nowadays1 these are biconcave disks1 but owing to their peculiar figure it is easily possible to misinterpret the appearances they present when seen through a poor lens1 and though ,dr4 ,thomas ,young and various other observers had come very near the truth regarding them1 unanimity of opinion was possible only after the verdict of the perfected microscope was given4 ,these blood corpuscles are so infinitesimal in size that something like five millions of them are found in each cubic millimetre of the blood1 yet they are isolated particles1 each having1 so to speak1 its own personality4 ,this1 of course1 had been known to microscopists since the days of the earliest lenses4 ,it had been noticed1 too1 by here and there an observer1 that certain of the solid tissues seemed to present something of a granular texture1 as if they1 too1 in their ultimate constitution1 were made up of particles4 ,and now1 as better and better lenses were constructed1 this idea gained ground constantly1 though for a time no one saw its full significance4 ,in the case of vegetable tissues1 indeed1 the fact that little particles encased a membranous covering1 and called cells1 are the ultimate visible units of structure had long been known4 ,but it was supposed that animal tissues differed radically from this construction4 ,the elementary particles of vegetables were regarded to a certain extent as individuals which composed the entire plant1 while1 on the other hand1 no such view was taken of the elementary parts of animals4 ,,robert ,,brown ,,and ,,the ,,cell ,,nucleus ,in the year #ahcc a further insight into the nature of the ultimate particles of plants was gained through the observation of the ,english microscopist ,robert ,brown1 who1 in the course of his microscopic studies of the epidermis of orchids1 discovered in the cells an opaque spot1 which he named the nucleus4 ,doubtless the same spot had been seen often enough before by other observers1 but ,brown was the first to recognize it as a component part of the vegetable cell and to give it a name4 ,i shall conclude my observations on ,orchideae1 said ,brown1 with a notice of some points of their general structure1 which chiefly relate to the cellular tissue4 ,in each cell of the epidermis of a great part of this family1 especially of those with membranous leaves1 a single circular areola1 generally somewhat more opaque than1 the membrane of the cell1 is observable4 ,this areola1 which is more or less distinctly granular1 is slightly convex1 and although it seems to be on the surface is in reality covered by the outer lamina of the cell4 ,there is no regularity as to its place in the cell2 it is not unfrequently1 however1 central or nearly so4 ,as only one areola belongs to each cell1 and as in many cases where it exists in the common cells of the epidermis1 it is also visible in the cutaneous glands or stomata1 and in these is always double--one being on each side of the limb--it is highly probable that the cutaneous gland is in all cases composed of two cells of peculiar form1 the line of union being the longitudinal axis of the disk or pore4 ,this areola1 or nucleus of the cell as perhaps it might be termed1 is not confined to the epidermis1 being also found1 not only in the pubescence of the surface1 particularly when jointed1 as in cypripedium1 but in many cases in the parenchyma or internal cells of the tissue1 especially when these are free from the deposition of granular matter4 ,in the compressed cells of the epidermis the nucleus is in a corresponding degree flattened2 but in the internal tissue it is often nearly spherical1 more or less firmly adhering to one of the walls1 and projecting into the cavity of the cell4 ,in this state it may not unfrequently be found in the substance of the column and in that of the perianthium4 ,the nucleus is manifest also in the tissue of the stigma1 where in accordance with the compression of the utriculi1 it has an intermediate form1 being neither so much flattened as in the epidermis nor so convex as it is in the internal tissue of the column4 ,i may here remark that ,i am acquainted with one case of apparent exception to the nucleus being solitary in each utriculus or cell--namely1 in ,bletia ,tankervilliae4 ,in the utriculi of the stigma of this plant1 ,i have generally1 though not always1 found a second areola apparently on the surface1 and composed of much larger granules than the ordinary nucleus1 which is formed of very minute granular matter1 and seems to be deep seated4 ,mr4 ,bauer has represented the tissue of the stigma1 in the species of ,bletia1 both before and1 as he believes1 after impregnation2 and in the latter state the utriculi are marked with from one to three areolae of similar appearance4 ,the nucleus may even be supposed to exist in the pollen of this family4 ,in the early stages of its formation1 at least a minute areola is of ten visible in the simple grain1 and in each of the constituent parts of cells of the compound grain4 ,but these areolae may perhaps rather be considered as merely the points of production of the tubes4 ,this nucleus of the cell is not confined to orchideae1 but is equally manifest in many other monocotyledonous families2 and ,i have even found it1 hitherto however in very few cases1 in the epidermis of dicotyledonous plants2 though in this primary division it may perhaps be said to exist in the early stages of development of the pollen4 ,among monocotyledons1 the orders in which it is most remarkable are ,liliaceae1 ,hemerocallideae1 ,asphodeleae1 ,irideae1 and ,commelineae4 ,in some plants belonging to this last-mentioned family1 especially in ,tradascantia virginica1 and several nearly related species1 it is uncommonly distinct1 not in the epidermis and in the jointed hairs of the filaments1 but in the tissue of the stigma1 in the cells of the ovulum even before impregnation1 and in all the stages of formation of the grains of pollen1 the evolution of which is so remarkable in tradascantia4 ,the few indications of the presence of this nucleus1 or areola1 that ,i have hitherto met with in the publications of botanists are chiefly in some figures of epidermis1 in the recent works of ,meyen and ,purkinje1 and in one case1 in ,m4 ,adolphe ,broigniart's memoir on the structure of leaves4 ,but so little importance seems to be attached to it that the appearance is not always referred to in the explanations of the figures in which it is represented4 ,mr4 ,bauer1 however1 who has also figured it in the utriculi of the stigma of ,bletia ,tankervilliae has more particularly noticed it1 and seems to consider it as only visible after impregnation47#b7 ,,schleiden ,,and ,,schwann ,,and ,,the ,,cell ,,theory ,that this newly recognized structure must be important in the economy of the cell was recognized by ,brown himself1 and by the celebrated ,german ,meyen1 who dealt with it in his work on vegetable physiology1 published not long afterwards2 but it remained for another ,german1 the professor of botany in the ,university of ,jena1 ,dr4 ,m4 ,j4 ,schleiden1 to bring the nucleus to popular attention1 and to assert its all-importance in the economy of the cell4 ,schleiden freely acknowledged his indebtedness to ,brown for first knowledge of the nucleus1 but he soon carried his studies of that structure far beyond those of its discoverer4 ,he came to believe that the nucleus is really the most important portion of the cell1 in that it is the original structure from which the remainder of the cell is developed4 ,hence he named it the cytoblast4 ,he outlined his views in an epochal paper published in ,muller's ,archives in #ahch1 under title of ,beitrage zur ,phytogenesis4 ,this paper is in itself of value1 yet the most important outgrowth of ,schleiden's observations of the nucleus did not spring from his own labors1 but from those of a friend to whom he mentioned his discoveries the year previous to their publication4 ,this friend was ,dr4 ,theodor ,schwann1 professor of physiology in the ,university of ,louvain4 ,at the moment when these observations were communicated to him ,schwann was puzzling over certain details of animal histology which he could not clearly explain4 ,his great teacher1 ,johannes ,muller1 had called attention to the strange resemblance to vegetable cells shown by certain cells of the chorda dorsalis 7the embryonic cord from which the spinal column is developed71 and ,schwann himself had discovered a corresponding similarity in the branchial cartilage of a tadpole4 ,then1 too1 the researches of ,friedrich ,henle had shown that the particles that make up the epidermis of animals are very cell-like in appearance4 ,indeed1 the cell-like character of certain animal tissues had come to be matter of common note among students of minute anatomy4 ,schwann felt that this similarity could not be mere coincidence1 but he had gained no clew to further insight until ,schleiden called his attention to the nucleus4 ,then at once he reasoned that if there really is the correspondence between vegetable and animal tissues that he suspected1 and if the nucleus is so important in the vegetable cell as ,schleiden believed1 the nucleus should also be found in the ultimate particles of animal tissues4 ,schwann's researches soon showed the entire correctness of this assumption4 ,a closer study of animal tissues under the microscope showed1 particularly in the case of embryonic tissues1 that opaque spots such as ,schleiden described are really to be found there in abundance--forming1 indeed1 a most characteristic phase of the structure4 ,the location of these nuclei at comparatively regular intervals suggested that they are found in definite compartments of the tissue1 as ,schleiden had shown to be the case with vegetables2 indeed1 the walls that separated such cell-like compartments one from another were in some cases visible4 ,particularly was this found to be the case with embryonic tissues1 and the study of these soon convinced ,schwann that his original surmise had been correct1 and that all animal tissues are in their incipiency composed of particles not unlike the ultimate particles of vegetables in short1 of what the botanists termed cells4 ,adopting this name1 ,schwann propounded what soon became famous as his cell theory1 under title of ,mikroskopische ,untersuchungen uber die ,ubereinstimmung in der ,structur und dent ,wachsthum der ,thiere und ,pflanzen4 ,so expeditious had been his work that this book was published early in #ahci1 only a few months after the appearance of ,schleiden's paper4 ,as the title suggests1 the main idea that actuated ,schwann was to unify vegetable and animal tissues4 ,accepting cell-structure as the basis of all vegetable tissues1 he sought to show that the same is true of animal tissues1 all the seeming diversities of fibre being but the alteration and development of what were originally simple cells4 ,and by cell ,schwann meant1 as did ,schleiden also1 what the word ordinarily implies--a cavity walled in on all sides4 ,he conceived that the ultimate constituents of all tissues were really such minute cavities1 the most important part of which was the cell wall1 with its associated nucleus4 ,he knew1 indeed1 that the cell might be filled with fluid contents1 but he regarded these as relatively subordinate in importance to the wall itself4 ,this1 however1 did not apply to the nucleus1 which was supposed to lie against the cell wall and in the beginning to generate it4 ,subsequently the wall might grow so rapidly as to dissociate itself from its contents1 thus becoming a hollow bubble or true cell2 but the nucleus1 as long as it lasted1 was supposed to continue in contact with the cell wall4 ,schleiden had even supposed the nucleus to be a constituent part of the wall1 sometimes lying enclosed between two layers of its substance1 and ,schwann quoted this view with seeming approval4 ,schwann believed1 however1 that in the mature cell the nucleus ceased to be functional and disappeared4 ,the main thesis as to the similarity of development of vegetable and animal tissues and the cellular nature of the ultimate constitution of both was supported by a mass of carefully gathered evidence which a multitude of microscopists at once confirmed1 so ,schwann's work became a classic almost from the moment of its publication4 ,of course various other workers at once disputed ,schwann's claim to priority of discovery1 in particular the ,english microscopist ,valentin1 who asserted1 not without some show of justice1 that he was working closely along the same lines4 ,put so1 for that matter1 were numerous others1 as ,henle1 ,turpin1 ,du-mortier1 ,purkinje1 and ,muller1 all of whom ,schwann himself had quoted4 ,moreover1 there were various physiologists who earlier than any of these had foreshadowed the cell theory--notably ,kaspar ,friedrich ,wolff1 towards the close of the previous century1 and ,treviranus about #ahjg1 ,but1 as we have seen in so many other departments of science1 it is one thing to foreshadow a discovery1 it is quite another to give it full expression and make it germinal of other discoveries4 ,and when ,schwann put forward the explicit claim that there is one universal principle of development for the elementary parts1 of organisms1 however different1 and this principle is the formation of cells1 he enunciated a doctrine which was for all practical purposes absolutely new and opened up a novel field for the microscopist to enter4 ,a most important era in physiology dates from the publication of his book in #ahci4 ,,the ,,cell ,,theory ,,elaborated ,that ,schwann should have gone to embryonic tissues for the establishment of his ideas was no doubt due very largely to the influence of the great ,russian ,karl ,ernst von ,baer1 who about ten years earlier had published the first part of his celebrated work on embryology1 and whose ideas were rapidly gaining ground1 thanks largely to the advocacy of a few men1 notably ,johannes ,muller1 in ,germany1 and ,william ,b4 ,carpenter1 in ,england1 and to the fact that the improved microscope had made minute anatomy popular4 ,schwann's researches made it plain that the best field for the study of the animal cell is here1 and a host of explorers entered the field4 ,the result of their observations was1 in the main1 to confirm the claims of ,schwann as to the universal prevalence of the cell4 ,the long-current idea that animal tissues grow only as a sort of deposit from the blood-vessels was now discarded1 and the fact of so-called plantlike growth of animal cells1 for which ,schwann contended1 was universally accepted4 ,yet the full measure of the affinity between the two classes of cells was not for some time generally apprehended4 ,indeed1 since the substance that composes the cell walls of plants is manifestly very different from the limiting membrane of the animal cell1 it was natural1 so long as the wall was considered the most essential part of the structure1 that the divergence between the two classes of cells should seem very pronounced4 ,and for a time this was the conception of the matter that was uniformly accepted4 ,but as time went on many observers had their attention called to the peculiar characteristics of the contents of the cell1 and were led to ask themselves whether these might not be more important than had been supposed4 ,in particular1 ,dr4 ,hugo von ,mohl1 professor of botany in the ,university of ,tubingen1 in the course of his exhaustive studies of the vegetable cell1 was impressed with the peculiar and characteristic appearance of the cell contents4 ,he observed universally within the cell an opaque1 viscid fluid1 having granules intermingled in it1 which made up the main substance of the cell1 and which particularly impressed him because under certain conditions it could be seen to be actively in motion1 its parts separated into filamentous streams4 ,von ,mohl called attention to the fact that this motion of the cell contents had been observed as long ago as #aggd by ,bonaventura ,corti1 and rediscovered in #ahjg by ,treviranus1 and that these observers had described the phenomenon under the most unsuitable name of 'rotation of the cell sap4' ,von ,mohl recognized that the streaming substance was something quite different from sap4 ,he asserted that the nucleus of the cell lies within this substance and not attached to the cell wall as ,schleiden had contended4 ,he saw1 too1 that the chlorophyl granules1 and all other of the cell contents1 are incorporated with the opaque1 viscid fluid1 and in #ahdf he had become so impressed with the importance of this universal cell substance that he gave it the name of protoplasm4 ,yet in so doing he had no intention of subordinating the cell wall4 ,the fact that ,payen1 in #ahdd1 had demonstrated that the cell walls of all vegetables1 high or low1 are composed largely of one substance1 cellulose1 tended to strengthen the position of the cell wall as the really essential structure1 of which the protoplasmic contents were only subsidiary products4 ,meantime1 however1 the students of animal histology were more and more impressed with the seeming preponderance of cell contents over cell walls in the tissues they studied4 ,they1 too1 found the cell to be filled with a viscid1 slimy fluid capable of motion4 ,to this ,dujardin gave the name of sarcode4 ,presently it came to be known1 through the labors of ,kolliker1 ,nageli1 ,bischoff1 and various others1 that there are numerous lower forms of animal life which seem to be composed of this sarcode1 without any cell wall whatever4 ,the same thing seemed to be true of certain cells of higher organisms1 as the blood corpuscles4 ,particularly in the case of cells that change their shape markedly1 moving about in consequence of the streaming of their sarcode1 did it seem certain that no cell wall is present1 or that1 if present1 its role must be insignificant4 ,and so histologists came to question whether1 after all1 the cell contents rather than the enclosing wall must not be the really essential structure1 and the weight of increasing observations finally left no escape from the conclusion that such is really the case4 ,but attention being thus focalized on the cell contents1 it was at once apparent that there is a far closer similarity between the ultimate particles of vegetables and those of animals than had been supposed4 ,cellulose and animal membrane being now regarded as more by-products1 the way was clear for the recognition of the fact that vegetable protoplasm and animal sarcode are marvellously similar in appearance and general properties4 ,the closer the observation the more striking seemed this similarity2 and finally1 about #ahfj1 it was demonstrated by ,heinrich de ,bary and by ,max ,schultze that the two are to all intents and purposes identical4 ,even earlier ,remak had reached a similar conclusion1 and applied ,von ,mohl's word protoplasm to animal cell contents1 and now this application soon became universal4 ,thenceforth this protoplasm was to assume the utmost importance in the physiological world1 being recognized as the universal physical basis of life1 vegetable and animal alike4 ,this amounted to the logical extension and culmination of ,schwann's doctrine as to the similarity of development of the two animate kingdoms4 ,yet at the same time it was in effect the banishment of the cell that ,schwann had defined4 ,the word cell was retained1 it is true1 but it no longer signified a minute cavity4 ,it now implied1 as ,schultze defined it1 a small mass of protoplasm endowed with the attributes of life4 ,this definition was destined presently to meet with yet another modification1 as we shall see2 but the conception of the protoplasmic mass as the essential ultimate structure1 which might or might not surround itself with a protective covering1 was a permanent addition to physiological knowledge4 ,the earlier idea had1 in effect1 declared the shell the most important part of the egg2 this developed view assigned to the yolk its true position4 ,in one other important regard the theory of ,schleiden and ,schwann now became modified4 ,this referred to the origin of the cell4 ,schwann had regarded cell growth as a kind of crystallization1 beginning with the deposit of a nucleus about a granule in the intercellular substance--the cytoblastema1 as ,schleiden called it4 ,but ,von ,mohl1 as early as #ahce1 had called attention to the formation of new vegetable cells through the division of a pre-existing cell4 ,ehrenberg1 another high authority of the time1 contended that no such division occurs1 and the matter was still in dispute when ,schleiden came forward with his discovery of so-called free cell-formation within the parent cell1 and this for a long time diverted attention from the process of division which ,von ,mohl had described4 ,all manner of schemes of cell-formation were put forward during the ensuing years by a multitude of observers1 and gained currency notwithstanding ,von ,mohl's reiterated contention that there are really but two ways in which the formation of new cells takes place--namely1 first1 through division of older cells2 secondly1 through the formation of secondary cells lying free in the cavity of a cell4 ,but gradually the researches of such accurate observers as ,unger1 ,nageli1 ,kolliker1 ,reichart1 and ,remak tended to confirm the opinion of ,von ,mohl that cells spring only from cells1 and finally ,rudolf ,virchow brought the matter to demonstration about #ahfj4 ,his ,omnis cellula e cellula became from that time one of the accepted data of physiology4 ,this was supplemented a little later by ,fleming's ,omnis nucleus e nucleo1 when still more refined methods of observation had shown that the part of the cell which always first undergoes change preparatory to new cell-formation is the all-essential nucleus4 ,thus the nucleus was restored to the important position which ,schwann and ,schleiden had given it1 but with greatly altered significance4 ,instead of being a structure generated de novo from non-cellular substance1 and disappearing as soon as its function of cell-formation was accomplished1 the nucleus was now known as the central and permanent feature of every cell1 indestructible while the cell lives1 itself the division-product of a pre-existing nucleus1 and the parent1 by division of its substance1 of other generations of nuclei4 ,the word cell received a final definition as a small mass of protoplasm supplied with a nucleus4 ,in this widened and culminating general view of the cell theory it became clear that every animate organism1 animal or vegetable1 is but a cluster of nucleated cells1 all of which1 in each individual case1 are the direct descendants of a single primordial cell of the ovum4 ,in the developed individuals of higher organisms the successive generations of cells become marvellously diversified in form and in specific functions2 there is a wonderful division of labor1 special functions being chiefly relegated to definite groups of cells2 but from first to last there is no function developed that is not present1 in a primitive way1 in every cell1 however isolated2 nor does the developed cell1 however specialized1 ever forget altogether any one of its primordial functions or capacities4 ,all physiology1 then1 properly interpreted1 becomes merely a study of cellular activities2 and the development of the cell theory takes its place as the great central generalization in physiology of the nineteenth century4 ,something of the later developments of this theory we shall see in another connection4 ,,animal ,,chemistry ,just at the time when the microscope was opening up the paths that were to lead to the wonderful cell theory1 another novel line of interrogation of the living organism was being put forward by a different set of observers4 ,two great schools of physiological chemistry had arisen--one under guidance of ,liebig and ,wohler1 in ,germany1 the other dominated by the great ,french master ,jean ,baptiste ,dumas4 ,liebig had at one time contemplated the study of medicine1 and ,dumas had achieved distinction in connection with ,prevost1 at ,geneva1 in the field of pure physiology before he turned his attention especially to chemistry4 ,both these masters1 therefore1 and ,wohler as well1 found absorbing interest in those phases of chemistry that have to do with the functions of living tissues2 and it was largely through their efforts and the labors of their followers that the prevalent idea that vital processes are dominated by unique laws was discarded and physiology was brought within the recognized province of the chemist4 ,so at about the time when the microscope had taught that the cell is the really essential structure of the living organism1 the chemists had come to understand that every function of the organism is really the expression of a chemical change--that each cell is1 in short1 a miniature chemical laboratory4 ,and it was this combined point of view of anatomist and chemist1 this union of hitherto dissociated forces1 that made possible the inroads into the unexplored fields of physiology that were effected towards the middle of the nineteenth century4 ,one of the first subjects reinvestigated and brought to proximal solution was the long-mooted question of the digestion of foods4 ,spallanzani and ,hunter had shown in the previous century that digestion is in some sort a solution of foods2 but little advance was made upon their work until #ahbd1 when ,prout detected the presence of hydrochloric acid in the gastric juice4 ,a decade later ,sprott and ,boyd detected the existence of peculiar glands in the gastric mucous membrane2 and ,cagniard la ,tour and ,schwann independently discovered that the really active principle of the gastric juice is a substance which was named pepsin1 and which was shown by ,schwann to be active in the presence of hydrochloric acid4 ,almost coincidently1 in #ahcf1 it was discovered by ,purkinje and ,pappenheim that another organ than the stomach--namely1 the pancreas--has a share in digestion1 and in the course of the ensuing decade it came to be known1 through the efforts of ,eberle1 ,valentin1 and ,claude ,bernard1 that this organ is all-important in the digestion of starchy and fatty foods4 ,it was found1 too1 that the liver and the intestinal glands have each an important share in the work of preparing foods for absorption1 as also has the saliva--that1 in short1 a coalition of forces is necessary for the digestion of all ordinary foods taken into the stomach4 ,and the chemists soon discovered that in each one of the essential digestive juices there is at least one substance having certain resemblances to pepsin1 though acting on different kinds of food4 ,the point of resemblance between all these essential digestive agents is that each has the remarkable property of acting on relatively enormous quantities of the substance which it can digest without itself being destroyed or apparently even altered4 ,in virtue of this strange property1 pepsin and the allied substances were spoken of as ferments1 but more recently it is customary to distinguish them from such organized ferments as yeast by designating them enzymes4 ,the isolation of these enzymes1 and an appreciation of their mode of action1 mark a long step towards the solution of the riddle of digestion1 but it must be added that we are still quite in the dark as to the real ultimate nature of their strange activity4 ,in a comprehensive view1 the digestive organs1 taken as a whole1 are a gateway between the outside world and the more intimate cells of the organism4 ,another equally important gateway is furnished by the lungs1 and here also there was much obscurity about the exact method of functioning at the time of the revival of physiological chemistry4 ,that oxygen is consumed and carbonic acid given off during respiration the chemists of the age of ,priestley and ,lavoisier had indeed made clear1 but the mistaken notion prevailed that it was in the lungs themselves that the important burning of fuel occurs1 of which carbonic acid is a chief product4 ,but now that attention had been called to the importance of the ultimate cell1 this misconception could not long hold its ground1 and as early as #ahdb ,liebig1 in the course of his studies of animal heat1 became convinced that it is not in the lungs1 but in the ultimate tissues to which they are tributary1 that the true consumption of fuel takes place4 ,reviving ,lavoisier's idea1 with modifications and additions1 ,liebig contended1 and in the face of opposition finally demonstrated1 that the source of animal heat is really the consumption of the fuel taken in through the stomach and the lungs4 ,he showed that all the activities of life are really the product of energy liberated solely through destructive processes1 amounting1 broadly speaking1 to combustion occurring in the ultimate cells of the organism4 ,here is his argument3 ,,liebig ,,on ,,animal ,,heat ,the oxygen taken into the system is taken out again in the same forms1 whether in summer or in winter2 hence we expire more carbon in cold weather1 and when the barometer is high1 than we do in warm weather2 and we must consume more or less carbon in our food in the same proportion2 in ,sweden more than in ,sicily2 and in our more temperate climate a full eighth more in winter than in summer4 ,even when we consume equal weights of food in cold and warm countries1 infinite wisdom has so arranged that the articles of food in different climates are most unequal in the proportion of carbon they contain4 ,the fruits on which the natives of the ,south prefer to feed do not in the fresh state contain more than twelve per cent4 of carbon1 while the blubber and train-oil used by the inhabitants of the arctic regions contain from sixty-six to eighty per cent4 of carbon4 ,it is no difficult matter1 in warm climates1 to study moderation in eating1 and men can bear hunger for a long time under the equator2 but cold and hunger united very soon exhaust the body4 ,the mutual action between the elements of the food and the oxygen conveyed by the circulation of the blood to every part of the body is the source of animal heat4 ,all living creatures whose existence depends on the absorption of oxygen possess within themselves a source of heat independent of surrounding objects4 ,this truth applies to all animals1 and extends besides to the germination of seeds1 to the flowering of plants1 and to the maturation of fruits4 ,it is only in those parts of the body to which arterial blood1 and with it the oxygen absorbed in respiration1 is conveyed that heat is produced4 ,hair1 wool1 or feathers do not possess an elevated temperature4 ,this high temperature of the animal body1 or1 as it may be called1 disengagement of heat1 is uniformly and under all circumstances the result of the combination of combustible substance with oxygen4 ,in whatever way carbon may combine with oxygen1 the act of combination cannot take place without the disengagement of heat4 ,it is a matter of indifference whether the combination takes place rapidly or slowly1 at a high or at a low temperature2 the amount of heat liberated is a constant quantity4 ,the carbon of the food1 which is converted into carbonic acid within the body1 must give out exactly as much heat as if it had been directly burned in the air or in oxygen gas2 the only difference is that the amount of heat produced is diffused over unequal times4 ,in oxygen the combustion is more rapid and the heat more intense2 in air it is slower1 the temperature is not so high1 but it continues longer4 ,it is obvious that the amount of heat liberated must increase or diminish with the amount of oxygen introduced in equal times by respiration4 ,those animals which respire frequently1 and consequently consume much oxygen1 possess a higher temperature than others which1 with a body of equal size to be heated1 take into the system less oxygen4 ,the temperature of a child 7#ajb degrees7 is higher than that of an adult 7#ii4e degrees74 ,that of birds 7#ajd to #aje4d degrees7 is higher than that of quadrupeds 7#ih4e to #ajj4d degrees71 or than that of fishes or amphibia1 whose proper temperature is from #c4g to #b4f degrees higher than that of the medium in which they live4 ,all animals1 strictly speaking1 are warm-blooded2 but in those only which possess lungs is the temperature of the body independent of the surrounding medium4 ,the most trustworthy observations prove that in all climates1 in the temperate zones as well as at the equator or the poles1 the temperature of the body in man1 and of what are commonly called warm-blooded animals1 is invariably the same2 yet how different are the circumstances in which they live4 ,the animal body is a heated mass1 which bears the same relation to surrounding objects as any other heated mass4 ,it receives heat when the surrounding objects are hotter1 it loses heat when they are colder than itself4 ,we know that the rapidity of cooling increases with the difference between the heated body and that of the surrounding medium--that is1 the colder the surrounding medium the shorter the time required for the cooling of the heated body4 ,how unequal1 then1 must be the loss of heat of a man at ,palermo1 where the actual temperature is nearly equal to that of the body1 and in the polar regions1 where the external temperature is from #gj to #ij degrees lower4 ,yet notwithstanding this extremely unequal loss of heat1 experience has shown that the blood of an inhabitant of the arctic circle has a temperature as high as that of the native of the ,south1 who lives in so different a medium4 ,this fact1 when its true significance is perceived1 proves that the heat given off to the surrounding medium is restored within the body with great rapidity4 ,this compensation takes place more rapidly in winter than in summer1 at the pole than at the equator4 ,now in different climates the quantity of oxygen introduced into the system of respiration1 as has been already shown1 varies according to the temperature of the external air2 the quantity of inspired oxygen increases with the loss of heat by external cooling1 and the quantity of carbon or hydrogen necessary to combine with this oxygen must be increased in like ratio4 ,it is evident that the supply of heat lost by cooling is effected by the mutual action of the elements of the food and the inspired oxygen1 which combine together4 ,to make use of a familiar1 but not on that account a less just illustration1 the animal body acts1 in this respect1 as a furnace1 which we supply with fuel4 ,it signifies nothing what intermediate forms food may assume1 what changes it may undergo in the body1 the last change is uniformly the conversion of carbon into carbonic acid and of its hydrogen into water2 the unassimilated nitrogen of the food1 along with the unburned or unoxidized carbon1 is expelled in the excretions4 ,in order to keep up in a furnace a constant temperature1 we must vary the supply of fuel according to the external temperature--that is1 according to the supply of oxygen4 ,in the animal body the food is the fuel2 with a proper supply of oxygen we obtain the heat given out during its oxidation or combustion47#c7 ,,blood ,,corpuscles1 ,,muscles1 ,,and ,,glands ,further researches showed that the carriers of oxygen1 from the time of its absorption in the lungs till its liberation in the ultimate tissues1 are the red corpuscles1 whose function had been supposed to be the mechanical one of mixing of the blood4 ,it transpired that the red corpuscles are composed chiefly of a substance which ,kuhne first isolated in crystalline form in #ahfe1 and which was named haemoglobin--a substance which has a marvellous affinity for oxygen1 seizing on it eagerly at the lungs vet giving it up with equal readiness when coursing among the remote cells of the body4 ,when freighted with oxygen it becomes oxyhaemoglobin and is red in color2 when freed from its oxygen it takes a purple hue2 hence the widely different appearance of arterial and venous blood1 which so puzzled the early physiologists4 ,this proof of the vitally important role played by the red-blood corpuscles led1 naturally1 to renewed studies of these infinitesimal bodies4 ,it was found that they may vary greatly in number at different periods in the life of the same individual1 proving that they may be both developed and destroyed in the adult organism4 ,indeed1 extended observations left no reason to doubt that the process of corpuscle formation and destruction may be a perfectly normal one--that1 in short1 every red-blood corpuscle runs its course and dies like any more elaborate organism4 ,they are formed constantly in the red marrow of bones1 and are destroyed in the liver1 where they contribute to the formation of the coloring matter of the bile4 ,whether there are other seats of such manufacture and destruction of the corpuscles is not yet fully determined4 ,nor are histologists agreed as to whether the red-blood corpuscles themselves are to be regarded as true cells1 or merely as fragments of cells budded out from a true cell for a special purpose2 but in either case there is not the slightest doubt that the chief function of the red corpuscle is to carry oxygen4 ,if the oxygen is taken to the ultimate cells before combining with the combustibles it is to consume1 it goes without saying that these combustibles themselves must be carried there also4 ,nor could it be in doubt that the chiefest of these ultimate tissues1 as regards1 quantity of fuel required1 are the muscles4 ,a general and comprehensive view of the organism includes1 then1 digestive apparatus and lungs as the channels of fuel-supply2 blood and lymph channels as the transportation system2 and muscle cells1 united into muscle fibres1 as the consumption furnaces1 where fuel is burned and energy transformed and rendered available for the purposes of the organism1 supplemented by a set of excretory organs1 through which the waste products--the ashes--are eliminated from the system4 ,but there remain1 broadly speaking1 two other sets of organs whose size demonstrates their importance in the economy of the organism1 yet whose functions are not accounted for in this synopsis4 ,these are those glandlike organs1 such as the spleen1 which have no ducts and produce no visible secretions1 and the nervous mechanism1 whose central organs are the brain and spinal cord4 ,what offices do these sets of organs perform in the great labor-specializing aggregation of cells which we call a living organism8 ,as regards the ductless glands1 the first clew to their function was given when the great ,frenchman ,claude ,bernard 7the man of whom his admirers loved to say1 ,he is not a physiologist merely2 he is physiology itself7 discovered what is spoken of as the glycogenic function of the liver4 ,the liver itself1 indeed1 is not a ductless organ1 but the quantity of its biliary output seems utterly disproportionate to its enormous size1 particularly when it is considered that in the case of the human species the liver contains normally about one-fifth of all the blood in the entire body4 ,bernard discovered that the blood undergoes a change of composition in passing through the liver4 ,the liver cells 7the peculiar forms of which had been described by ,purkinje1 ,henle1 and ,dutrochet about #ahch7 have the power to convert certain of the substances that come to them into a starchlike compound called glycogen1 and to store this substance away till it is needed by the organism4 ,this capacity of the liver cells is quite independent of the bile-making power of the same cells2 hence the discovery of this glycogenic function showed that an organ may have more than one pronounced and important specific function4 ,but its chief importance was in giving a clew to those intermediate processes between digestion and final assimilation that are now known to be of such vital significance in the economy of the organism4 ,in the forty odd years that have elapsed since this pioneer observation of ,bernard1 numerous facts have come to light showing the extreme importance of such intermediate alterations of food-supplies in the blood as that performed by the liver4 ,it has been shown that the pancreas1 the spleen1 the thyroid gland1 the suprarenal capsules are absolutely essential1 each in its own way1 to the health of the organism1 through metabolic changes which they alone seem capable of performing2 and it is suspected that various other tissues1 including even the muscles themselves1 have somewhat similar metabolic capacities in addition to their recognized functions4 ,but so extremely intricate is the chemistry of the substances involved that in no single case has the exact nature of the metabolisms wrought by these organs been fully made out4 ,each is in its way a chemical laboratory indispensable to the right conduct of the organism1 but the precise nature of its operations remains inscrutable4 ,the vast importance of the operations of these intermediate organs is unquestioned4 ,a consideration of the functions of that other set of organs known collectively as the nervous system is reserved for a later chapter4 ,,vi4 ,,theories ,,of ,,organic ,,evolution ,,goethe ,,and ,,the ,,metamorphosis ,,of ,,parts ,when ,coleridge said of ,humphry ,davy that he might have been the greatest poet of his time had he not chosen rather to be the greatest chemist1 it is possible that the enthusiasm of the friend outweighed the caution of the critic4 ,but however that may be1 it is beyond dispute that the man who actually was the greatest poet of that time might easily have taken the very highest rank as a scientist had not the muse distracted his attention4 ,indeed1 despite these distractions1 ,johann ,wolfgang von ,goethe achieved successes in the field of pure science that would insure permanent recognition for his name had he never written a stanza of poetry4 ,such is the versatility that marks the highest genius4 ,it was in #agij that ,goethe published the work that laid the foundations of his scientific reputation--the work on the ,metamorphoses of ,plants1 in which he advanced the novel doctrine that all parts of the flower are modified or metamorphosed leaves4 ,every one who observes the growth of plants1 even superficially1 wrote ,goethe1 will notice that certain external parts of them become transformed at times and go over into the forms of the contiguous parts1 now completely1 now to a greater or less degree4 ,thus1 for example1 the single flower is transformed into a double one when1 instead of stamens1 petals are developed1 which are either exactly like the other petals of the corolla in form1 and color or else still bear visible signs of their origin4 ,when we observe that it is possible for a plant in this way to take a step backward1 we shall give so much the more heed to the regular course of nature and learn the laws of transformation according to which she produces one part through another1 and displays the most varying forms through the modification of one single organ4 ,let us first direct our attention to the plant at the moment when it develops out of the seed-kernel4 ,the first organs of its upward growth are known by the name of cotyledons2 they have also been called seed-leaves4 ,they often appear shapeless1 filled with new matter1 and are just as thick as they are broad4 ,their vessels are unrecognizable and are hardly to be distinguished from the mass of the whole2 they bear almost no resemblance to a leaf1 and we could easily be misled into regarding them as special organs4 ,occasionally1 however1 they appear as real leaves1 their vessels are capable of the most minute development1 their similarity to the following leaves does not permit us to take them for special organs1 but we recognize them instead to be the first leaves of the stalk4 ,the cotyledons are mostly double1 and there is an observation to be made here which will appear still more important as we proceed--that is1 that the leaves of the first node are often paired1 even when the following leaves of the stalk stand alternately upon it4 ,here we see an approximation and a joining of parts which nature afterwards separates and places at a distance from one another4 ,it is still more remarkable when the cotyledons take the form of many little leaves gathered about an axis1 and the stalk which grows gradually from their midst produces the following leaves arranged around it singly in a whorl4 ,this may be observed very exactly in the growth of the pinus species4 ,here a corolla of needles forms at the same time a calyx1 and we shall have occasion to remember the present case in connection with similar phenomena later4 ,on the other hand1 we observe that even the cotyledons which are most like a leaf when compared with the following leaves of the stalk are always more undeveloped or less developed4 ,this is chiefly noticeable in their margin which is extremely simple and shows few traces of indentation4 ,a few or many of the next following leaves are often already present in the seed1 and lie enclosed between the cotyledons2 in their folded state they are known by the name of plumules4 ,their form1 as compared with the cotyledons and the following leaves1 varies in different plants4 ,their chief point of variance1 however1 from the cotyledons is that they are flat1 delicate1 and formed like real leaves generally4 ,they are wholly green1 rest on a visible node1 and can no longer deny their relationship to the following leaves of the stalk1 to which1 however1 they are usually still inferior1 in so far as that their margin is not completely developed4 ,the further development1 however1 goes on ceaselessly in the leaf1 from node to node2 its midrib is elongated1 and more or less additional ribs stretch out from this towards the sides4 ,the leaves now appear notched1 deeply indented1 or composed of several small leaves1 in which last case they seem to form complete little branches4 ,the date-palm furnishes a striking example of such a successive transformation of the simplest leaf form4 ,a midrib is elongated through a succession of several leaves1 the single fan-shaped leaf becomes torn and diverted1 and a very complicated leaf is developed1 which rivals a branch in form4 ,the transition to inflorescence takes place more or less rapidly4 ,in the latter case we usually observe that the leaves of the stalk loose their different external divisions1 and1 on the other hand1 spread out more or less in their lower parts where they are attached to the stalk4 ,if the transition takes place rapidly1 the stalk1 suddenly become thinner and more elongated since the node of the last-developed leaf1 shoots up and collects several leaves around an axis at its end4 ,that the petals of the calyx are precisely the same organs which have hitherto appeared as leaves on the stalk1 but now stand grouped about a common centre in an often very different form1 can1 as it seems to me1 be most clearly demonstrated4 ,already in connection with the cotyledons above1 we noticed a similar working of nature4 ,the first species1 while they are developing out of the seed-kernel1 display a radiate crown of unmistakable needles2 and in the first childhood of these plants we see already indicated that force of nature whereby when they are older their flowering and fruit-giving state will be produced4 ,we see this force of nature1 which collects several leaves around an axis1 produce a still closer union and make these approximated1 modified leaves still more unrecognizable by joining them together either wholly or partially4 ,the bell-shaped or so-called one-petalled calices represent these cloudy connected leaves1 which1 being more or less indented from above1 or divided1 plainly show their origin4 ,we can observe the transition from the calyx to the corolla in more than one instance1 for1 although the color of the calyx is still usually green1 and like the color of the leaves of the stalk1 it nevertheless often varies in one or another of its parts--at the tips1 the margins1 the back1 or even1 the inward side--while the outer still remains on green4 ,the relationship of the corolla to the leaves of the stalk is shown in more than one way1 since on the stalks of some plants appear leaves which are already more or less colored long before they approach inflorescence2 others are fully colored when near inflorescence4 ,nature also goes over at once to the corolla1 sometimes by skipping over the organs of the calyx1 and in such a case we likewise have an opportunity to observe that leaves of the stalk become transformed into petals4 ,thus on the stalk of tulips1 for instance1 there sometimes appears an almost completely developed and colored petal4 ,even more remarkable is the case when such a leaf1 half green and half of it belonging to the stalk1 remains attached to the latter1 while another colored part is raised with the corolla1 and the leaf is thus torn in two4 ,the relationship between the petals and stamens is very close4 ,in some instances nature makes the transition regular--e4g41 among the ,canna and several plants of the same family4 ,a true1 little-modified petal is drawn together on its upper margin1 and produces a pollen sac1 while the rest of the petal takes the place of the stamen4 ,in double flowers we can observe this transition in all its stages4 ,in several kinds of roses1 within the fully developed and colored petals there appear other ones which are drawn together in the middle or on the side4 ,this drawing together is produced by a small weal1 which appears as a more or less complete pollen sac1 and in the same proportion the leaf approaches the simple form of a stamen4 ,the pistil in many cases looks almost like a stamen without anthers1 and the relationship between the formation of the two is much closer than between the other parts4 ,in retrograde fashion nature often produces cases where the style and stigma 7,narben7 become retransformed into petals--that is1 the ,ranunculus ,asiaticus becomes double by transforming the stigma and style of the fruit-receptacle into real petals1 while the stamens are often found unchanged immediately behind the corolla4 ,in the seed receptacles1 in spite of their formation1 of their special object1 and of their method of being joined together1 we cannot fail to recognize the leaf form4 ,thus1 for instance1 the pod would be a simple leaf folded and grown together on its margin2 the siliqua would consist of more leaves folded over another2 the compound receptacles would be explained as being several leaves which1 being united above one centre1 keep their inward parts separate and are joined on their margins4 ,we can convince ourselves of this by actual sight when such composite capsules fall apart after becoming ripe1 because then every part displays an opened pod47#a7 ,the theory thus elaborated of the metamorphosis of parts was presently given greater generality through extension to the animal kingdom1 in the doctrine which ,goethe and ,oken advanced independently1 that the vertebrate skull is essentially a modified and developed vertebra4 ,these were conceptions worthy of a poet--impossible1 indeed1 for any mind that had not the poetic faculty of correlation4 ,but in this case the poet's vision was prophetic of a future view of the most prosaic science4 ,the doctrine of metamorphosis of parts soon came to be regarded as of fundamental importance4 ,but the doctrine had implications that few of its early advocates realized4 ,if all the parts of a flower--sepal1 petal1 stamen1 pistil1 with their countless deviations of contour and color--are but modifications of the leaf1 such modification implies a marvellous differentiation and development4 ,to assert that a stamen is a metamorphosed leaf means1 if it means anything1 that in the long sweep of time the leaf has by slow or sudden gradations changed its character through successive generations1 until the offspring1 so to speak1 of a true leaf has become a stamen4 ,but if such a metamorphosis as this is possible--if the seemingly wide gap between leaf and stamen may be spanned by the modification of a line of organisms--where does the possibility of modification of organic type find its bounds8 ,why may not the modification of parts go on along devious lines until the remote descendants of an organism are utterly unlike that organism8 ,why may we not thus account for the development of various species of beings all sprung from one parent stock8 ,that1 too1 is a poet's dream2 but is it only a dream8 ,goethe thought not4 ,out of his studies of metamorphosis of parts there grew in his mind the belief that the multitudinous species of plants and animals about us have been evolved from fewer and fewer earlier parent types1 like twigs of a giant tree drawing their nurture from the same primal root4 ,it was a bold and revolutionary thought1 and the world regarded it as but the vagary of a poet4 ,,erasmus ,,darwin ,just at the time when this thought was taking form in ,goethe's brain1 the same idea was germinating in the mind of another philosopher1 an ,englishman of international fame1 ,dr4 ,erasmus ,darwin1 who1 while he lived1 enjoyed the widest popularity as a poet1 the rhymed couplets of his ,botanic ,garden being quoted everywhere with admiration4 ,and posterity repudiating the verse which makes the body of the book1 yet grants permanent value to the book itself1 because1 forsooth1 its copious explanatory foot-notes furnish an outline of the status of almost every department of science of the time4 ,but even though he lacked the highest art of the versifier1 ,darwin had1 beyond peradventure1 the imagination of a poet coupled with profound scientific knowledge2 and it was his poetic insight1 correlating organisms seemingly diverse in structure and imbuing the lowliest flower with a vital personality1 which led him to suspect that there are no lines of demarcation in nature4 ,can it be1 he queries1 that one form of organism has developed from another2 that different species are really but modified descendants of one parent stock8 ,the alluring thought nestled in his mind and was nurtured there1 and grew in a fixed belief1 which was given fuller expression in his ,zoonomia and in the posthumous ,temple of ,nature4 ,here is his rendering of the idea as versified in the ,temple of ,nature3 ,organic life beneath the shoreless waves ,was born1 and nursed in ,ocean's pearly caves2 ,first forms minute1 unseen by spheric glass1 ,move on the mud1 or pierce the watery mass2 ,these1 as successive generations bloom1 ,new powers acquire and larger limbs assume2 ,whence countless groups of vegetation spring1 ,and breathing realms of fin1 and feet1 and wing4 ,thus the tall ,oak1 the giant of the wood1 ,which bears ,britannia's thunders on the flood2 ,the ,whale1 unmeasured monster of the main2 ,the lordly lion1 monarch of the plain2 ,the eagle1 soaring in the realms of air1 ,whose eye1 undazzled1 drinks the solar glare2 ,imperious man1 who rules the bestial crowd1 ,of language1 reason1 and reflection proud1 ,with brow erect1 who scorns this earthy sod1 ,and styles himself the image of his ,god-- ,arose from rudiments of form and sense1 ,an embryon point or microscopic ens67#b7 ,here1 clearly enough1 is the idea of evolution4 ,but in that day there was little proof forthcoming of its validity that could satisfy any one but a poet1 and when ,erasmus ,darwin died1 in #ahjb1 the idea of transmutation of species was still but an unsubstantiated dream4 ,it was a dream1 however1 which was not confined to ,goethe and ,darwin4 ,even earlier the idea had come more or less vaguely to another great dreamer--and worker--of ,germany1 ,immanuel ,kant1 and to several great ,frenchmen1 including ,de ,maillet1 ,maupertuis1 ,robinet1 and the famous naturalist ,buffon--a man who had the imagination of a poet1 though his message was couched in most artistic prose4 ,not long after the middle of the eighteenth century ,buffon had put forward the idea of transmutation of species1 and he reiterated it from time to time from then on till his death in #aghh4 ,but the time was not yet ripe for the idea of transmutation of species to burst its bonds4 ,and yet this idea1 in a modified or undeveloped form1 had taken strange hold upon the generation that was upon the scene at the close of the eighteenth century4 ,vast numbers of hitherto unknown species of animals had been recently discovered in previously unexplored regions of the globe1 and the wise men were sorely puzzled to account for the disposal of all of these at the time of the deluge4 ,it simplified matters greatly to suppose that many existing species had been developed since the episode of the ark by modification of the original pairs4 ,the remoter bearings of such a theory were overlooked for the time1 and the idea that ,american animals and birds1 for example1 were modified descendants of ,old-,world forms--the jaguar of the leopard1 the puma of the lion1 and so on--became a current belief with that class of humanity who accept almost any statement as true that harmonizes with their prejudices without realizing its implications4 ,thus it is recorded with eclat that the discovery of the close proximity of ,america at the northwest with ,asia removes all difficulties as to the origin of the ,occidental faunas and floras1 since ,oriental species might easily have found their way to ,america on the ice1 and have been modified as we find them by the well-known influence of climate4 ,and the persons who gave expression to this idea never dreamed of its real significance4 ,in truth1 here was the doctrine of evolution in a nutshell1 and1 because its ultimate bearings were not clear1 it seemed the most natural of doctrines4 ,but most of the persons who advanced it would have turned from it aghast could they have realized its import4 ,as it was1 however1 only here and there a man like ,buffon reasoned far enough to inquire what might be the limits of such assumed transmutation2 and only here and there a ,darwin or a ,goethe reached the conviction that there are no limits4 ,,lamarck ,,versus ,,cuvier ,and even ,goethe and ,darwin had scarcely passed beyond that tentative stage of conviction in which they held the thought of transmutation of species as an ancillary belief not ready for full exposition4 ,there was one of their contemporaries1 however1 who1 holding the same conception1 was moved to give it full explication4 ,this was the friend and disciple of ,buffon1 ,jean ,baptiste de ,lamarck4 ,possessed of the spirit of a poet and philosopher1 this great ,frenchman had also the widest range of technical knowledge1 covering the entire field of animate nature4 ,the first half of his long life was devoted chiefly to botany1 in which he attained high distinction4 ,then1 just at the beginning of the nineteenth century1 he turned to zoology1 in particular to the lower forms of animal life4 ,studying these lowly organisms1 existing and fossil1 he was more and more impressed with the gradations of form everywhere to be seen2 the linking of diverse families through intermediate ones2 and in particular with the predominance of low types of life in the earlier geological strata4 ,called upon constantly to classify the various forms of life in the course of his systematic writings1 he found it more and more difficult to draw sharp lines of demarcation1 and at last the suspicion long harbored grew into a settled conviction that there is really no such thing as a species of organism in nature2 that species is a figment of the human imagination1 whereas in nature there are only individuals4 ,that certain sets of individuals are more like one another than like other sets is of course patent1 but this only means1 said ,lamarck1 that these similar groups have had comparatively recent common ancestors1 while dissimilar sets of beings are more remotely related in consanguinity4 ,but trace back the lines of descent far enough1 and all will culminate in one original stock4 ,all forms of life whatsoever are modified descendants of an original organism4 ,from lowest to highest1 then1 there is but one race1 one species1 just as all the multitudinous branches and twigs from one root are but one tree4 ,for purposes of convenience of description1 we may divide organisms into orders1 families1 genera1 species1 just as we divide a tree into root1 trunk1 branches1 twigs1 leaves2 but in the one case1 as in the other1 the division is arbitrary and artificial4 ,in ,philosophie ,zoologique 7#ahji71 ,lamarck first explicitly formulated his ideas as to the transmutation of species1 though he had outlined them as early as #ahja4 ,in this memorable publication not only did he state his belief more explicitly and in fuller detail than the idea had been expressed by any predecessor1 but he took another long forward step1 carrying him far beyond all his forerunners except ,darwin1 in that he made an attempt to explain the way in which the transmutation of species had been brought about4 ,the changes have been wrought1 he said1 through the unceasing efforts of each organism to meet the needs imposed upon it by its environment4 ,constant striving means the constant use of certain organs4 ,thus a bird running by the seashore is constantly tempted to wade deeper and deeper in pursuit of food2 its incessant efforts tend to develop its legs1 in accordance with the observed principle that the use of any organ tends to strengthen and develop it4 ,but such slightly increased development of the legs is transmitted to the off spring of the bird1 which in turn develops its already improved legs by its individual efforts1 and transmits the improved tendency4 ,generation after generation this is repeated1 until the sum of the infinitesimal variations1 all in the same direction1 results in the production of the long-legged wading-bird4 ,in a similar way1 through individual effort and transmitted tendency1 all the diversified organs of all creatures have been developed--the fin of the fish1 the wing of the bird1 the hand of man2 nay1 more1 the fish itself1 the bird1 the man1 even4 ,collectively the organs make up the entire organism2 and what is true of the individual organs must be true also of their ensemble1 the living being4 ,whatever might be thought of ,lamarck's explanation of the cause of transmutation--which really was that already suggested by ,erasmus ,darwin--the idea of the evolution for which he contended was but the logical extension of the conception that ,american animals are the modified and degenerated descendants of ,european animals4 ,but people as a rule are little prone to follow ideas to their logical conclusions1 and in this case the conclusions were so utterly opposed to the proximal bearings of the idea that the whole thinking world repudiated them with acclaim4 ,the very persons who had most eagerly accepted the idea of transmutation of ,european species into ,american species1 and similar limited variations through changed environment1 because of the relief thus given the otherwise overcrowded ark1 were now foremost in denouncing such an extension of the doctrine of transmutation as ,lamarck proposed4 ,and1 for that matter1 the leaders of the scientific world were equally antagonistic to the ,lamarckian hypothesis4 ,cuvier in particular1 once the pupil of ,lamarck1 but now his colleague1 and in authority more than his peer1 stood out against the transmutation doctrine with all his force4 ,he argued for the absolute fixity of species1 bringing to bear the resources of a mind which1 as a mere repository of facts1 perhaps never was excelled4 ,as a final and tangible proof of his position1 he brought forward the bodies of ibises that had been embalmed by the ancient ,egyptians1 and showed by comparison that these do not differ in the slightest particular from the ibises that visit the ,nile to-day4 ,cuvier's reasoning has such great historical interest--being the argument of the greatest opponent of evolution of that day--that we quote it at some length4 ,the following objections1 he says1 have already been started against my conclusions4 ,why may not the presently existing races of mammiferous land quadrupeds be mere modifications or varieties of those ancient races which we now find in the fossil state1 which modifications may have been produced by change of climate and other local circumstances1 and since raised to the present excessive difference by the operations of similar causes during a long period of ages8 ,this objection may appear strong to those who believe in the indefinite possibility of change of form in organized bodies1 and think that1 during a succession of ages and by alterations of habitudes1 all the species may change into one another1 or one of them give birth to all the rest4 ,yet to these persons the following answer may be given from their own system3 ,if the species have changed by degrees1 as they assume1 we ought to find traces of this gradual modification4 ,thus1 between the palaeotherium and the species of our own day1 we should be able to discover some intermediate forms2 and yet no such discovery has ever been made4 ,since the bowels of the earth have not preserved monuments of this strange genealogy1 we have no right to conclude that the ancient and now extinct species were as permanent in their forms and characters as those which exist at present2 or1 at least1 that the catastrophe which destroyed them did not leave sufficient time for the productions of the changes that are alleged to have taken place4 ,in order to reply to those naturalists who acknowledge that the varieties of animals are restrained by nature within certain limits1 it would be necessary to examine how far these limits extend4 ,this is a very curious inquiry1 and in itself exceedingly interesting under a variety of relations1 but has been hitherto very little attended to4444 ,wild animals which subsist upon herbage feel the influence of climate a little more extensively1 because there is added to it the influence of food1 both in regard to its abundance and its quality4 ,thus the elephants of one forest are larger than those of another2 their tusks also grow somewhat longer in places where their food may happen to be more favorable for the production of the substance of ivory4 ,the same may take place in regard to the horns of stags and reindeer4 ,but let us examine two elephants1 the most dissimilar that can be conceived1 we shall not discover the smallest difference in the number and articulations of the bones1 the structure of the teeth1 etc444444444 ,nature appears also to have guarded against the alterations of species which might proceed from mixture of breeds by influencing the various species of animals with mutual aversion from one another4 ,hence all the cunning and all the force that man is able to exert is necessary to accomplish such unions1 even between species that have the nearest resemblances4 ,and when the mule breeds that are thus produced by these forced conjunctions happen to be fruitful1 which is seldom the case1 this fecundity never continues beyond a few generations1 and would not probably proceed so far without a continuance of the same cares which excited it at first4 ,thus we never see in a wild state intermediate productions between the hare and the rabbit1 between the stag and the doe1 or between the marten and the weasel4 ,but the power of man changes this established order1 and continues to produce all these intermixtures of which the various species are susceptible1 but which they would never produce if left to themselves4 ,the degrees of these variations are proportional to the intensity of the causes that produced them--namely1 the slavery or subjection under which those animals are to man4 ,they do not proceed far in half-domesticated species4 ,in the cat1 for example1 a softer or harsher fur1 more brilliant or more varied colors1 greater or less size--these form the whole extent of variety in the species2 the skeleton of the cat of ,angora differs in no regular and constant circumstances from the wild-cat of ,europe4444 ,the most remarkable effects of the influence of man are produced upon that animal which he has reduced most completely under subjection4 ,dogs have been transported by mankind into every part of the world and have submitted their action to his entire direction4 ,regulated in their unions by the pleasure or caprice of their masters1 the almost endless varieties of dogs differ from one another in color1 in length1 and abundance of hair1 which is sometimes entirely wanting2 in their natural instincts2 in size1 which varies in measure as one to five1 mounting in some instances to more than a hundredfold in bulk2 in the form of their ears1 noses1 and tails2 in the relative length of their legs2 in the progressive development of the brain1 in several of the domesticated varieties occasioning alterations even in the form of the head1 some of them having long1 slender muzzles with a flat forehead1 others having short muzzles with a forehead convex1 etc41 insomuch that the apparent difference between a mastiff and a water-spaniel and between a greyhound and a pugdog are even more striking than between almost any of the wild species of a genus44444444 ,it follows from these observations that animals have certain fixed and natural characters which resist the effects of every kind of influence1 whether proceeding from natural causes or human interference2 and we have not the smallest reason to suspect that time has any more effect on them than climate4 ,i am aware that some naturalists lay prodigious stress upon the thousands which they can call into action by a dash of their pens4 ,in such matters1 however1 our only way of judging as to the effects which may be produced by a long period of time is by multiplying1 as it were1 such as are produced by a shorter time4 ,with this view ,i have endeavored to collect all the ancient documents respecting the forms of animals2 and there are none equal to those furnished by the ,egyptians1 both in regard to their antiquity and abundance4 ,they have not only left us representatives of animals1 but even their identical bodies embalmed and preserved in the catacombs4 ,i have examined1 with the greatest attention1 the engraved figures of quadrupeds and birds brought from ,egypt to ancient ,rome1 and all these figures1 one with another1 have a perfect resemblance to their intended objects1 such as they still are to-day4 ,from all these established facts1 there does not seem to be the smallest foundation for supposing that the new genera which ,i have discovered or established among extraneous fossils1 such as the paleoetherium1 anoplotherium1 megalonyx1 mastodon1 pterodactylis1 etc41 have ever been the sources of any of our present animals1 which only differ so far as they are influenced by time or climate4 ,even if it should prove true1 which ,i am far from believing to be the case1 that the fossil elephants1 rhinoceroses1 elks1 and bears do not differ further from the existing species of the same genera than the present races of dogs differ among themselves1 this would by no means be a sufficient reason to conclude that they were of the same species2 since the races or varieties of dogs have been influenced by the trammels of domesticity1 which those other animals never did1 and indeed never could1 experience47#c7 ,to ,cuvier's argument from the fixity of ,egyptian mummified birds and animals1 as above stated1 ,lamarck replied that this proved nothing except that the ibis had become perfectly adapted to its ,egyptian surroundings in an early day1 historically speaking1 and that the climatic and other conditions of the ,nile ,valley had not since then changed4 ,his theory1 he alleged1 provided for the stability of species under fixed conditions quite as well as for transmutation under varying conditions4 ,but1 needless to say1 the popular verdict lay with ,cuvier2 talent won for the time against genius1 and ,lamarck was looked upon as an impious visionary4 ,his faith never wavered1 however4 ,he believed that he had gained a true insight into the processes of animate nature1 and he reiterated his hypotheses over and over1 particularly in the introduction to his ,histoire ,naturelle des ,animaux sans ,vertebres1 in #ahae1 and in his ,systeme des ,connaissances ,positives de l',homme1 in #ahbj4 ,he lived on till #ahbi1 respected as a naturalist1 but almost unrecognized as a prophet4 ,,tentative ,,advances ,while the names of ,darwin and ,goethe1 and in particular that of ,lamarck1 must always stand out in high relief in this generation as the exponents of the idea of transmutation of species1 there are a few others which must not be altogether overlooked in this connection4 ,of these the most conspicuous is that of ,gottfried ,reinhold ,treviranus1 a ,german naturalist physician1 professor of mathematics in the lyceum at ,bremen4 ,it was an interesting coincidence that ,treviranus should have published the first volume of his ,biologie1 oder ,philosophie der lebenden ,natur1 in which his views on the transmutation of species were expounded1 in #ahjb1 the same twelvemonth in which ,lamarck's first exposition of the same doctrine appeared in his ,recherches sur l',organisation des ,corps ,vivants4 ,it is singular1 too1 that ,lamarck1 in his ,hydrogelogie of the same date1 should independently have suggested biology as an appropriate word to express the general science of living things4 ,it is significant of the tendency of thought of the time that the need of such a unifying word should have presented itself simultaneously to independent thinkers in different countries4 ,that same memorable year1 ,lorenz ,oken1 another philosophical naturalist1 professor in the ,university of ,zurich1 published the preliminary outlines of his ,philosophie der ,natur1 which1 as developed through later publications1 outlined a theory of spontaneous generation and of evolution of species4 ,thus it appears that this idea was germinating in the minds of several of the ablest men of the time during the first decade of our century4 ,but the singular result of their various explications was to give sudden check to that undercurrent of thought which for some time had been setting towards this conception4 ,as soon as it was made clear whither the concession that animals may be changed by their environment must logically trend1 the recoil from the idea was instantaneous and fervid4 ,then for a generation ,cuvier was almost absolutely dominant1 and his verdict was generally considered final4 ,there was1 indeed1 one naturalist of authority in ,france who had the hardihood to stand out against ,cuvier and his school1 and who was in a position to gain a hearing1 though by no means to divide the following4 ,this was ,etienne ,geoffroy ,saint-,hilaire1 the famous author of the ,philosophie ,anatomique1 and for many years the colleague of ,lamarck at the ,jardin des ,plantes4 ,like ,goethe1 ,geoffroy was pre-eminently an anatomist1 and1 like the great ,german1 he had early been impressed with the resemblances between the analogous organs of different classes of beings4 ,he conceived the idea that an absolute unity of type prevails throughout organic nature as regards each set of organs4 ,out of this idea grew his gradually formed belief that similarity of structure might imply identity of origin--that1 in short1 one species of animal might have developed from another4 ,geoffroy's grasp of this idea of transmutation was by no means so complete as that of ,lamarck1 and he seems never to have fully determined in his own mind just what might be the limits of such development of species4 ,certainly he nowhere includes all organic creatures in one line of descent1 as ,lamarck had done2 nevertheless1 he held tenaciously to the truth as he saw it1 in open opposition to ,cuvier1 with whom he held a memorable debate at the ,academy of ,sciences in #ahcj--the debate which so aroused the interest and enthusiasm of ,goethe1 but which1 in the opinion of nearly every one else1 resulted in crushing defeat for ,geoffrey1 and brilliant1 seemingly final1 victory for the advocate of special creation and the fixity of species4 ,with that all ardent controversy over the subject seemed to end1 and for just a quarter of a century to come there was published but a single argument for transmutation of species which attracted any general attention whatever4 ,this oasis in a desert generation was a little book called ,vestiges of the ,natural ,history of ,creation1 which appeared anonymously in ,england in #ahdd1 and which passed through numerous editions1 and was the subject of no end of abusive and derisive comment4 ,this book1 the authorship of which remained for forty years a secret1 is now conceded to have been the work of ,robert ,chambers1 the well-known ,english author and publisher4 ,the book itself is remarkable as being an avowed and unequivocal exposition of a general doctrine of evolution1 its view being as radical and comprehensive as that of ,lamarck himself4 ,but it was a resume of earlier efforts rather than a new departure1 to say nothing of its technical shortcomings1 which may best be illustrated by a quotation4 ,the whole question1 says ,chambers1 stands thus3 ,for the theory of universal order--that is1 order as presiding in both the origin and administration of the world--we have the testimony of a vast number of facts in nature1 and this one in addition--that whatever is left from the domain of ignorance1 and made undoubted matter of science1 forms a new support to the same doctrine4 ,the opposite view1 once predominant1 has been shrinking for ages into lesser space1 and now maintains a footing only in a few departments of nature which happen to be less liable than others to a clear investigation4 ,the chief of these1 if not almost the only one1 is the origin of the organic kingdoms4 ,so long as this remains obscure1 the supernatural will have a certain hold upon enlightened persons4 ,should it ever be cleared up in a way that leaves no doubt of a natural origin of plants and animals1 there must be a complete revolution in the view which is generally taken of the relation of the ,father of our being4 ,this prepares the way for a few remarks on the present state of opinion with regard to the origin of organic nature4 ,the great difficulty here is the apparent determinateness of species4 ,these forms of life being apparently unchangeable1 or at least always showing a tendency to return to the character from which they have diverged1 the idea arises that there can have been no progression from one to another2 each must have taken its special form1 independently of other forms1 directly from the appointment of the ,creator4 ,the ,edinburgh ,review writer says1 'they were created by the hand of ,god and adapted to the conditions of the period4' ,now it is1 in the first place1 not certain that species constantly maintain a fixed character1 for we have seen that what were long considered as determinate species have been transmuted into others4 ,passing1 however1 from this fact1 as it is not generally received among men of science1 there remain some great difficulties in connection with the idea of special creation4 ,first we should have to suppose1 as pointed out in my former volume1 a most startling diversity of plan in the divine workings1 a great general plan or system of law in the leading events of world-making1 and a plan of minute1 nice operation1 and special attention in some of the mere details of the process4 ,the discrepancy between the two conceptions is surely overpowering1 when we allow ourselves to see the whole matter in a steady and rational light4 ,there is1 also1 the striking fact of an ascertained historical progress of plants and animals in the order of their organization2 marine and cellular plants and invertebrated animals first1 afterwards higher examples of both4 ,in an arbitrary system we had surely no reason to expect mammals after reptiles2 yet in this order they came4 ,the writer in the ,edinburgh ,review speaks of animals as coming in adaptation to conditions1 but this is only true in a limited sense4 ,the groves which formed the coal-beds might have been a fitting habitation for reptiles1 birds1 and mammals1 as such groves are at the present day2 yet we see none of the last of these classes and hardly any traces of the two first at that period of the earth4 ,where the iguanodon lived the elephant might have lived1 but there was no elephant at that time4 ,the sea of the ,lower ,silurian era was capable of supporting fish1 but no fish existed4 ,it hence forcibly appears that theatres of life must have remained unserviceable1 or in the possession of a tenantry inferior to what might have enjoyed them1 for many ages3 there surely would have been no such waste allowed in a system where ,omnipotence was working upon the plan of minute attention to specialities4 ,the fact seems to denote that the actual procedure of the peopling of the earth was one of a natural kind1 requiring a long space of time for its evolution4 ,in this supposition the long existence of land without land animals1 and more particularly without the noblest classes and orders1 is only analogous to the fact1 not nearly enough present to the minds of a civilized people1 that to this day the bulk of the earth is a waste as far as man is concerned4 ,another startling objection is in the infinite local variation of organic forms4 ,did the vegetable and animal kingdoms consist of a definite number of species adapted to peculiarities of soil and climate1 and universally distributed1 the fact would be in harmony with the idea of special exertion4 ,but the truth is that various regions exhibit variations altogether without apparent end or purpose4 ,professor ,henslow enumerates forty-five distinct flowers or sets of plants upon the surface of the earth1 notwithstanding that many of these would be equally suitable elsewhere4 ,the animals of different continents are equally various1 few species being the same in any two1 though the general character may conform4 ,the inference at present drawn from this fact is that there must have been1 to use the language of the ,rev4 ,dr4 ,pye ,smith1 'separate and original creations1 perhaps at different and respectively distinct epochs4' ,it seems hardly conceivable that rational men should give an adherence to such a doctrine when we think of what it involves4 ,in the single fact that it necessitates a special fiat of the inconceivable ,author of this sand-cloud of worlds to produce the flora of ,st4 ,helena1 we read its more than sufficient condemnation4 ,it surely harmonizes far better with our general ideas of nature to suppose that1 just as all else in this far-spread science was formed on the laws impressed upon it at first by its ,author1 so also was this4 ,an exception presented to us in such a light appears admissible only when we succeed in forbidding our minds to follow out those reasoning processes to which1 by another law of the ,almighty1 they tend1 and for which they are adapted47#d7 ,such reasoning as this naturally aroused bitter animadversions1 and cannot have been without effect in creating an undercurrent of thought in opposition to the main trend of opinion of the time4 ,but the book can hardly be said to have done more than that4 ,indeed1 some critics have denied it even this merit4 ,after its publication1 as before1 the conception of transmutation of species remained in the popular estimation1 both lay and scientific1 an almost forgotten heresy4 ,it is true that here and there a scientist of greater or less repute--as ,von ,buch1 ,meckel1 and ,von ,baer in ,germany1 ,bory ,saint-,vincent in ,france1 ,wells1 ,grant1 and ,matthew in ,england1 and ,leidy in ,america--had expressed more or less tentative dissent from the doctrine of special creation and immutability of species1 but their unaggressive suggestions1 usually put forward in obscure publications1 and incidentally1 were utterly overlooked and ignored4 ,and so1 despite the scientific advances along many lines at the middle of the century1 the idea of the transmutability of organic races had no such prominence1 either in scientific or unscientific circles1 as it had acquired fifty years before4 ,special creation held the day1 seemingly unopposed4 ,,darwin ,,and ,,the ,,origin ,,of ,,species ,but even at this time the fancied security of the special-creation hypothesis was by no means real4 ,though it seemed so invincible1 its real position was that of an apparently impregnable fortress beneath which1 all unbeknown to the garrison1 a powder-mine has been dug and lies ready for explosion4 ,for already there existed in the secluded work-room of an ,english naturalist1 a manuscript volume and a portfolio of notes which might have sufficed1 if given publicity1 to shatter the entire structure of the special-creation hypothesis4 ,the naturalist who1 by dint of long and patient effort1 had constructed this powder-mine of facts was ,charles ,robert ,darwin1 grandson of the author of ,zoonomia4 ,as long ago as ,july #a1 #ahcg1 young ,darwin1 then twenty-eight years of age1 had opened a private journal1 in which he purposed to record all facts that came to him which seemed to have any bearing on the moot point of the doctrine of transmutation of species4 ,four or five years earlier1 during the course of that famous trip around the world with ,admiral ,fitzroy1 as naturalist to the ,beagle1 ,darwin had made the personal observations which first tended to shake his belief of the fixity of species4 ,in ,south ,america1 in the ,pampean formation1 he had discovered great fossil animals covered with armor like that on the existing armadillos1 and had been struck with this similarity of type between ancient and existing faunas of the same region4 ,he was also greatly impressed by the manner in which closely related species of animals were observed to replace one another as he proceeded southward over the continent2 and by the ,south-,american character of most of the productions of the ,galapagos ,archipelago1 and more especially by the manner in which they differ slightly on each island of the group1 none of the islands appearing to be very ancient in a geological sense4 ,at first the full force of these observations did not strike him2 for1 under sway of ,lyell's geological conceptions1 he tentatively explained the relative absence of life on one of the ,galapagos ,islands by suggesting that perhaps no species had been created since that island arose4 ,but gradually it dawned upon him that such facts as he had observed could only be explained on the supposition that species gradually become modified4 ,from then on1 as he afterwards asserted1 the subject haunted him2 hence the journal of #ahcg4 ,it will thus be seen that the idea of the variability of species came to ,charles ,darwin as an inference from personal observations in the field1 not as a thought borrowed from books4 ,he had1 of course1 read the works of his grandfather much earlier in life1 but the arguments of ,zoonomia and ,the ,temple of ,nature had not served in the least to weaken his acceptance of the current belief in fixity of species4 ,nor had he been more impressed with the doctrine of ,lamarck1 so closely similar to that of his grandfather4 ,indeed1 even after his ,south-,american experience had aroused him to a new point of view he was still unable to see anything of value in these earlier attempts at an explanation of the variation of species4 ,in opening his journal1 therefore1 he had no preconceived notion of upholding the views of these or any other makers of hypotheses1 nor at the time had he formulated any hypothesis of his own4 ,his mind was open and receptive2 he was eager only for facts which might lead him to an understanding of a problem which seemed utterly obscure4 ,it was something to feel sure that species have varied2 but how have such variations been brought about8 ,it was not long before ,darwin found a clew which he thought might lead to the answer he sought4 ,in casting about for facts he had soon discovered that the most available field for observation lay among domesticated animals1 whose numerous variations within specific lines are familiar to every one4 ,thus under domestication creatures so tangibly different as a mastiff and a terrier have sprung from a common stock4 ,so have the ,shetland pony1 the thoroughbred1 and the draught-horse4 ,in short1 there is no domesticated animal that has not developed varieties deviating more or less widely from the parent stock4 ,now1 how has this been accomplished8 ,why1 clearly1 by the preservation1 through selective breeding1 of seemingly accidental variations4 ,thus one horseman1 by constantly selecting animals that chance to have the right build and stamina1 finally develops a race of running-horses2 while another horseman1 by selecting a different series of progenitors1 has developed a race of slow1 heavy draught animals4 ,so far1 so good2 the preservation of accidental variations through selective breeding is plainly a means by which races may be developed that are very different from their original parent form4 ,but this is under man's supervision and direction4 ,by what process could such selection be brought about among creatures in a state of nature8 ,here surely was a puzzle1 and one that must be solved before another step could be taken in this direction4 ,the key to the solution of this puzzle came into ,darwin's mind through a chance reading of the famous essay on ,population which ,thomas ,robert ,malthus had published almost half a century before4 ,this essay1 expositing ideas by no means exclusively original with ,malthus1 emphasizes the fact that organisms tend to increase at a geometrical ratio through successive generations1 and hence would overpopulate the earth if not somehow kept in check4 ,cogitating this thought1 ,darwin gained a new insight into the processes of nature4 ,he saw that in virtue of this tendency of each race of beings to overpopulate the earth1 the entire organic world1 animal and vegetable1 must be in a state of perpetual carnage and strife1 individual against individual1 fighting for sustenance and life4 ,that idea fully imagined1 it becomes plain that a selective influence is all the time at work in nature1 since only a few individuals1 relatively1 of each generation can come to maturity1 and these few must1 naturally1 be those best fitted to battle with the particular circumstances in the midst of which they are placed4 ,in other words1 the individuals best adapted to their surroundings will1 on the average1 be those that grow to maturity and produce offspring4 ,to these offspring will be transmitted the favorable peculiarities4 ,thus these peculiarities will become permanent1 and nature will have accomplished precisely what the human breeder is seen to accomplish4 ,grant that organisms in a state of nature vary1 however slightly1 one from another 7which is indubitable71 and that such variations will be transmitted by a parent to its offspring 7which no one then doubted72 grant1 further1 that there is incessant strife among the various organisms1 so that only a small proportion can come to maturity--grant these things1 said ,darwin1 and we have an explanation of the preservation of variations which leads on to the transmutation of species themselves4 ,this wonderful coign of vantage ,darwin had reached by #ahci4 ,here was the full outline of his theory2 here were the ideas which afterwards came to be embalmed in familiar speech in the phrases spontaneous variation1 and the survival of the fittest1 through natural selection4 ,after such a discovery any ordinary man would at once have run through the streets of science1 so to speak1 screaming ,eureka6 ,not so ,darwin4 ,he placed the manuscript outline of his theory in his portfolio1 and went on gathering facts bearing on his discovery4 ,in #ahdd he made an abstract in a manuscript book of the mass of facts by that time accumulated4 ,he showed it to his friend ,hooker1 made careful provision for its publication in the event of his sudden death1 then stored it away in his desk and went ahead with the gathering of more data4 ,this was the unexploded powder-mine to which ,i have just referred4 ,twelve years more elapsed--years during which the silent worker gathered a prodigious mass of facts1 answered a multitude of objections that arose in his own mind1 vastly fortified his theory4 ,all this time the toiler was an invalid1 never knowing a day free from illness and discomfort1 obliged to husband his strength1 never able to work more than an hour and a half at a stretch2 yet he accomplished what would have been vast achievements for half a dozen men of robust health4 ,two friends among the eminent scientists of the day knew of his labors--,sir ,joseph ,hooker1 the botanist1 and ,sir ,charles ,lyell1 the geologist4 ,gradually ,hooker had come to be more than half a convert to ,darwin's views4 ,lyell was still sceptical1 yet he urged ,darwin to publish his theory without further delay lest he be forestalled4 ,at last the patient worker decided to comply with this advice1 and in #ahef he set to work to make another and fuller abstract of the mass of data he had gathered4 ,and then a strange thing happened4 ,after ,darwin had been at work on his abstract about two years1 but before he had published a line of it1 there came to him one day a paper in manuscript1 sent for his approval by a naturalist friend named ,alfred ,russel ,wallace1 who had been for some time at work in the ,east ,india ,archipelago4 ,he read the paper1 and1 to his amazement1 found that it contained an outline of the same theory of natural selection which he himself had originated and for twenty years had worked upon4 ,working independently1 on opposite sides of the globe1 ,darwin and ,wallace had hit upon the same explanation of the cause of transmutation of species4 ,were ,wallace's paper an abstract of my unpublished manuscript of #ahdd1 said ,darwin1 it could not better express my ideas4 ,here was a dilemma4 ,to publish this paper with no word from ,darwin would give ,wallace priority1 and wrest from ,darwin the credit of a discovery which he had made years before his codiscoverer entered the field4 ,yet1 on the other hand1 could ,darwin honorably do otherwise than publish his friend's paper and himself remain silent8 ,it was a complication well calculated to try a man's soul4 ,darwin's was equal to the test4 ,keenly alive to the delicacy of the position1 he placed the whole matter before his friends ,hooker and ,lyell1 and left the decision as to a course of action absolutely to them4 ,needless to say1 these great men did the one thing which insured full justice to all concerned4 ,they counselled a joint publication1 to include on the one hand ,wallace's paper1 and on the other an abstract of ,darwin's ideas1 in the exact form in which it had been outlined by the author in a letter to ,asa ,gray in the previous year--an abstract which was in ,gray's hands before ,wallace's paper was in existence4 ,this joint production1 together with a full statement of the facts of the case1 was presented to the ,linnaean ,society of ,london by ,hooker and ,lyell on the evening of ,july #a1 #aheh1 this being1 by an odd coincidence1 the twenty-first anniversary of the day on which ,darwin had opened his journal to collect facts bearing on the species question4 ,not often before in the history of science has it happened that a great theory has been nurtured in its author's brain through infancy and adolescence to its full legal majority before being sent out into the world4 ,thus the fuse that led to the great powder-mine had been lighted4 ,the explosion itself came more than a year later1 in ,november1 #ahei1 when ,darwin1 after thirteen months of further effort1 completed the outline of his theory1 which was at first begun as an abstract for the ,linnaean ,society1 but which grew to the size of an independent volume despite his efforts at condensation1 and which was given that ever-to-be-famous title1 ,the ,origin of ,species by ,means of ,natural ,selection1 or the ,preservation of ,favored ,races in the ,struggle for ,life4 ,and what an explosion it was6 ,the joint paper of #aheh had made a momentary flare1 causing the hearers1 as ,hooker said1 to speak of it with bated breath1 but beyond that it made no sensation4 ,what the result was when the ,origin itself appeared no one of our generation need be told4 ,the rumble and roar that it made in the intellectual world have not yet altogether ceased to echo after more than forty years of reverberation4 ,,new ,,champions ,to the ,origin of ,species1 then1 and to its author1 ,charles ,darwin1 must always be ascribed chief credit for that vast revolution in the fundamental beliefs of our race which has come about since #ahei1 and which made the second half of the century memorable4 ,but it must not be overlooked that no such sudden metamorphosis could have been effected had it not been for the aid of a few notable lieutenants1 who rallied to the standards of the leader immediately after the publication of the ,origin4 ,darwin had all along felt the utmost confidence in the ultimate triumph of his ideas4 ,our posterity1 he declared1 in a letter to ,hooker1 will marvel as much about the current belief 7in special creation7 as we do about fossil shells having been thought to be created as we now see them4 ,but he fully realized that for the present success of his theory of transmutation the championship of a few leaders of science was all-essential4 ,he felt that if he could make converts of ,hooker and ,lyell and of ,thomas ,henry ,huxley at once1 all would be well4 ,his success in this regard1 as in others1 exceeded his expectations4 ,hooker was an ardent disciple from reading the proof-sheets before the book was published2 ,lyell renounced his former beliefs and fell into line a few months later2 while ,huxley1 so soon as he had mastered the central idea of natural selection1 marvelled that so simple yet all-potent a thought had escaped him so long1 and then rushed eagerly into the fray1 wielding the keenest dialectic blade that was drawn during the entire controversy4 ,then1 too1 unexpected recruits were found in ,sir ,john ,lubbock and ,john ,tyndall1 who carried the war eagerly into their respective territories2 while ,herbert ,spencer1 who had advocated a doctrine of transmutation on philosophic grounds some years before ,darwin published the key to the mystery--and who himself had barely escaped independent discovery of that key--lent his masterful influence to the cause4 ,in ,america the famous botanist ,asa ,gray1 who had long been a correspondent of ,darwin's but whose advocacy of the new theory had not been anticipated1 became an ardent propagandist2 while in ,germany ,ernst ,heinrich ,haeckel1 the youthful but already noted zoologist1 took up the fight with equal enthusiasm4 ,against these few doughty champions--with here and there another of less general renown--was arrayed1 at the outset1 practically all ,christendom4 ,the interest of the question came home to every person of intelligence1 whatever his calling1 and the more deeply as it became more and more clear how far-reaching are the real bearings of the doctrine of natural selection4 ,soon it was seen that should the doctrine of the survival of the favored races through the struggle for existence win1 there must come with it as radical a change in man's estimate of his own position as had come in the day when1 through the efforts of ,copernicus and ,galileo1 the world was dethroned from its supposed central position in the universe4 ,the whole conservative majority of mankind recoiled from this necessity with horror4 ,and this conservative majority included not laymen merely1 but a vast preponderance of the leaders of science also4 ,with the open-minded minority1 on the other hand1 the theory of natural selection made its way by leaps and bounds4 ,its delightful simplicity--which at first sight made it seem neither new nor important--coupled with the marvellous comprehensiveness of its implications1 gave it a hold on the imagination1 and secured it a hearing where other theories of transmutation of species had been utterly scorned4 ,men who had found ,lamarck's conception of change through voluntary effort ridiculous1 and the vaporings of the ,vestiges altogether despicable1 men whose scientific cautions held them back from ,spencer's deductive argument1 took eager hold of that tangible1 ever-present principle of natural selection1 and were led on and on to its goal4 ,hour by hour the attitude of the thinking world towards this new principle changed2 never before was so great a revolution wrought so suddenly4 ,nor was this merely because the times were ripe or men's minds prepared for evolution4 ,darwin himself bears witness that this was not altogether so4 ,all through the years in which he brooded this theory he sounded his scientific friends1 and could find among them not one who acknowledged a doctrine of transmutation4 ,the reaction from the stand-point of ,lamarck and ,erasmus ,darwin and ,goethe had been complete1 and when ,charles ,darwin avowed his own conviction he expected always to have it met with ridicule or contempt4 ,in #aheg there was but one man speaking with any large degree of authority in the world who openly avowed a belief in transmutation of species--that man being ,herbert ,spencer4 ,but the ,origin of ,species came1 as ,huxley has said1 like a flash in the darkness1 enabling the benighted voyager to see the way4 ,the score of years during which its author had waited and worked had been years well spent4 ,darwin had become1 as he himself says1 a veritable ,croesus1 overwhelmed with his riches in facts--facts of zoology1 of selective artificial breeding1 of geographical distribution of animals1 of embryology1 of paleontology4 ,he had massed his facts about his theory1 condensed them and recondensed1 until his volume of five hundred pages was an encyclopaedia in scope4 ,during those long years of musing he had thought out almost every conceivable objection to his theory1 and in his book every such objection was stated with fullest force and candor1 together with such reply as the facts at command might dictate4 ,it was the force of those twenty years of effort of a master-mind that made the sudden breach in the breaswtorksic of current thought4 ,once this breach was effected the work of conquest went rapidly on4 ,day by day squads of the enemy capitulated and struck their arms4 ,by the time another score of years had passed the doctrine of evolution had become the working hypothesis of the scientific world4 ,the revolution had been effected4 ,and from amid the wreckage of opinion and belief stands forth the figure of ,charles ,darwin1 calm1 imperturbable1 serene2 scatheless to ridicule1 contumely1 abuse2 unspoiled by ultimate success2 unsullied alike by the strife and the victory--take him for all in all1 for character1 for intellect1 for what he was and what he did1 perhaps the most ,socratic figure of the century4 ,when1 in #ahhb1 he died1 friend and foe alike conceded that one of the greatest sons of men had rested from his labors1 and all the world felt it fitting that the remains of ,charles ,darwin should be entombed in ,westminster ,abbey close beside the honored grave of ,isaac ,newton4 ,nor were there many who would dispute the justice of ,huxley's estimate of his accomplishment3 ,he found a great truth trodden under foot4 ,reviled by bigots1 and ridiculed by all the world1 he lived long enough to see it1 chiefly by his own efforts1 irrefragably established in science1 inseparably incorporated with the common thoughts of men1 and only hated and feared by those who would revile but dare not4 ,,the ,,origin ,,of ,,the ,,fittest ,wide as are the implications of the great truth which ,darwin and his co-workers established1 however1 it leaves quite untouched the problem of the origin of those favored variations upon which it operates4 ,that such variations are due to fixed and determinate causes no one understood better than ,darwin2 but in his original exposition of his doctrine he made no assumption as to what these causes are4 ,he accepted the observed fact of variation--as constantly witnessed1 for example1 in the differences between parents and offspring--and went ahead from this assumption4 ,but as soon as the validity of the principle of natural selection came to be acknowledged speculators began to search for the explanation of those variations which1 for purposes of argument1 had been provisionally called spontaneous4 ,herbert ,spencer had all along dwelt on this phase of the subject1 expounding the ,lamarckian conceptions of the direct influence of the environment 7an idea which had especially appealed to ,buffon and to ,geoffroy ,saint-,hilaire71 and of effort in response to environment and stimulus as modifying the individual organism1 and thus supplying the basis for the operation of natural selection4 ,haeckel also became an advocate of this idea1 and presently there arose a so-called school of neo-,lamarckians1 which developed particular strength and prominence in ,america under the leadership of ,professors ,a4 ,hyatt and ,e4 ,d4 ,cope4 ,but just as the tide of opinion was turning strongly in this direction1 an utterly unexpected obstacle appeared in the form of the theory of ,professor ,august ,weismann1 put forward in #ahhc1 which antagonized the ,lamarckian conception 7though not touching the ,darwinian1 of which ,weismann is a firm upholder7 by denying that individual variations1 however acquired by the mature organism1 are transmissible4 ,the flurry which this denial created has not yet altogether subsided1 but subsequent observations seem to show that it was quite disproportionate to the real merits of the case4 ,notwithstanding ,professor ,weismann's objections1 the balance of evidence appears to favor the view that the ,lamarckian factor of acquired variations stands as the complement of the ,darwinian factor of natural selection in effecting the transmutation of species4 ,even though this partial explanation of what ,professor ,cope calls the origin of the fittest be accepted1 there still remains one great life problem which the doctrine of evolution does not touch4 ,the origin of species1 genera1 orders1 and classes of beings through endless transmutations is in a sense explained2 but what of the first term of this long series8 ,whence came that primordial organism whose transmuted descendants make up the existing faunas and floras of the globe8 ,there was a time1 soon after the doctrine of evolution gained a hearing1 when the answer to that question seemed to some scientists of authority to have been given by experiment4 ,recurring to a former belief1 and repeating some earlier experiments1 the director of the ,museum of ,natural ,history at ,rouen1 ,m4 ,f4 ,a4 ,pouchet1 reached the conclusion that organic beings are spontaneously generated about us constantly1 in the familiar processes of putrefaction1 which were known to be due to the agency of microscopic bacteria4 ,but in #ahfb ,louis ,pasteur proved that this seeming spontaneous generation is in reality due to the existence of germs in the air4 ,notwithstanding the conclusiveness of these experiments1 the claims of ,pouchet were revived in ,england ten years later by ,professor ,bastian2 but then the experiments of ,john ,tyndall1 fully corroborating the results of ,pasteur1 gave a final quietus to the claim of spontaneous generation as hitherto formulated4 ,there for the moment the matter rests4 ,but the end is not yet4 ,fauna and flora are here1 and1 thanks to ,lamarck and ,wallace and ,darwin1 their development1 through the operation of those secondary causes which we call laws of nature1 has been proximally explained4 ,the lowest forms of life have been linked with the highest in unbroken chains of descent4 ,meantime1 through the efforts of chemists and biologists1 the gap between the inorganic and the organic worlds1 which once seemed almost infinite1 has been constantly narrowed4 ,already philosophy can throw a bridge across that gap4 ,but inductive science1 which builds its own bridges1 has not yet spanned the chasm1 small though it appear4 ,until it shall have done so1 the bridge of organic evolution is not quite complete2 yet even as it stands to-day it is perhaps the most stupendous scientific structure of the nineteenth century4 ,,vii4 ,,eighteenth-,,century ,,medicine ,,the ,,system ,,of ,,boerhaave ,at least two pupils of ,william ,harvey distinguished themselves in medicine1 ,giorgio ,baglivi 7#affi-agjg71 who has been called the ,italian ,sydenham1 and ,hermann ,boerhaave 7#affh-agch74 ,the work of ,baglivi was hardly begun before his early death removed one of the most promising of the early eighteenth-century physicians4 ,like ,boerhaave1 he represents a type of skilled1 practical clinitian rather than the abstract scientist4 ,one of his contributions to medical literature is the first accurate description of typhoid1 or1 as he calls it1 mesenteric fever4 ,if for nothing else1 ,boerhaave must always be remembered as the teacher of ,von ,haller1 but in his own day he was the widest known and the most popular teacher in the medical world4 ,he was the idol of his pupils at ,leyden1 who flocked to his lectures in such numbers that it became necessary to tear down the walls of ,leyden to accommodate them4 ,his fame extended not only all over ,europe but to ,asia1 ,north ,america1 and even into ,south ,america4 ,a letter sent him from ,china was addressed to ,boerhaave in ,europe4 ,his teachings represent the best medical knowledge of his day1 a high standard of morality1 and a keen appreciation of the value of observation2 and it was through such teachings imparted to his pupils and advanced by them1 rather than to any new discoveries1 that his name is important in medical history4 ,his arrangement and classification of the different branches of medicine are interesting as representing the attitude of the medical profession towards these various branches at that time4 ,in the first place we consider ,life2 then ,health1 afterwards ,diseases2 and lastly their several ,remedies4 ,health the first general branch of ,physic in our ,institutions is termed ,physiology1 or the ,animal ,oeconomy2 demonstrating the several ,parts of the human ,body1 with their ,mechanism and ,actions4 ,the second branch of ,physic is called ,pathology1 treating of ,diseases1 their ,differences1 ,causes and ,effects1 or ,symptoms2 by which the human ,body is known to vary from its healthy state4 ,the third part of ,physic is termed ,semiotica1 which shows the ,signs distinguishing between sickness and ,health1 ,diseases and their ,causes in the human ,body2 it also imports the ,state and ,degrees of ,health and ,diseases1 and presages their future ,events4 ,the fourth general branch of ,physic is termed ,hygiene1 or ,prophylaxis4 ,the fifth and last part of ,physic is called ,therapeutica2 which instructs us in the ,nature1 ,preparation and uses of the ,materia ,medica2 and the methods of applying the same1 in order to cure ,diseases and restore lost ,health47#a7 ,from this we may gather that his general view of medicine was not unlike that taken at the present time4 ,boerhaave's doctrines were arranged into a system by ,friedrich ,hoffmann1 of ,halle 7#affj-agdb71 this system having the merit of being simple and more easily comprehended than many others4 ,in this system forces were considered inherent in matter1 being expressed as mechanical movements1 and determined by mass1 number1 and weight4 ,similarly1 forces express themselves in the body by movement1 contraction1 and relaxation1 etc41 and life itself is movement1 particularly movement of the heart4 ,life and death are1 therefore1 mechanical phenomena1 health is determined by regularly recurring movements1 and disease by irregularity of them4 ,the body is simply a large hydraulic machine1 controlled by the aether or sensitive soul1 and the chief centre of this soul lies in the medulla4 ,in the practical application of medicines to diseases ,hoffman used simple remedies1 frequently with happy results1 for whatever the medical man's theory may be he seldom has the temerity to follow it out logically1 and use the remedies indicated by his theory to the exclusion of long-established1 although perhaps purely empirical1 remedies4 ,consequently1 many vague theorists have been excellent practitioners1 and ,hoffman was one of these4 ,some of the remedies he introduced are still in use1 notably the spirits of ether1 or ,hoffman's anodyne4 ,,animists1 ,,vitalists1 ,,and ,,organicists ,besides ,hoffman's system of medicine1 there were numerous others during the eighteenth century1 most of which are of no importance whatever2 but three1 at least1 that came into existence and disappeared during the century are worthy of fuller notice4 ,one of these1 the ,animists1 had for its chief exponent ,georg ,ernst ,stahl of phlogiston fame2 another1 the ,vitalists1 was championed by ,paul ,joseph ,barthez 7#agcd-ahjf72 and the third was the ,organicists4 ,this last1 while agreeing with the other two that vital activity cannot be explained by the laws of physics and chemistry1 differed in not believing that life was due to some spiritual entity1 but rather to the structure of the body itself4 ,the ,animists taught that the soul performed functions of ordinary life in man1 while the life of lower animals was controlled by ordinary mechanical principles4 ,stahl supported this theory ardently1 sometimes violently1 at times declaring that there were no longer any doctors1 only mechanics and chemists4 ,he denied that chemistry had anything to do with medicine1 and1 in the main1 discarded anatomy as useless to the medical man4 ,the soul1 he thought1 was the source of all vital movement2 and the immediate cause of death was not disease but the direct action of the soul4 ,when through some lesion1 or because the machinery of the body has become unworkable1 as in old age1 the soul leaves the body and death is produced4 ,the soul ordinarily selects the channels of the circulation1 and the contractile parts1 as the route for influencing the body4 ,hence in fever the pulse is quickened1 due to the increased activity of the soul1 and convulsions and spasmodic movements in disease are due1 to the1 same cause4 ,stagnation of the blood was supposed to be a fertile cause of diseases1 and such diseases were supposed to arise mostly from plethora--an all-important element in ,stahl's therapeutics4 ,by many this theory is regarded as an attempt on the part of the pious ,stahl to reconcile medicine and theology in a way satisfactory to both physicians and theologians1 but1 like many conciliatory attempts1 it was violently opposed by both doctors and ministers4 ,a belief in such a theory would lead naturally to simplicity in therapeutics1 and in this respect at least ,stahl was consistent4 ,since the soul knew more about the body than any physician could know1 ,stahl conceived that it would be a hinderance rather than a help for the physician to interfere with complicated doses of medicine4 ,as he advanced in age this view of the administration of drugs grew upon him1 until after rejecting quinine1 and finally opium1 he at last used only salt and water in treating his patients4 ,from this last we may judge that his system1 if not doing much good1 was at least doing little harm4 ,the theory of the ,vitalists was closely allied to that of the ,animists1 and its most important representative1 ,paul ,joseph ,barthez1 was a cultured and eager scientist4 ,after an eventful and varied career as physician1 soldier1 editor1 lawyer1 and philosopher in turn1 he finally returned to the field of medicine1 was made consulting physician by ,napoleon in #ahjb1 and died in ,paris four years later4 ,the theory that he championed was based on the assumption that there was a vital principle1 the nature of which was unknown1 but which differed from the thinking mind1 and was the cause of the phenomena of life4 ,this vital principle differed from the soul1 and was not exhibited in human beings alone1 but even in animals and plants4 ,this force1 or whatever it might be called1 was supposed to be present everywhere in the body1 and all diseases were the results of it4 ,the theory of the ,organicists1 like that of the ,animists and ,vitalists1 agreed with the other two that vital activity could not be explained by the laws of physics and chemistry1 but1 unlike them1 it held that it was a part of the structure of the body itself4 ,naturally the practical physicians were more attracted by this tangible doctrine than by vague theories which converted diseases into unknown derangements of some equally unknown 'principle4' ,it is perhaps straining a point to include this brief description of these three schools of medicine in the history of the progress of the science4 ,but1 on the whole1 they were negatively at least prominent factors in directing true progress along its proper channel1 showing what courses were not to be pursued4 ,some one has said that science usually stumbles into the right course only after stumbling into all the wrong ones2 and if this be only partially true1 the wrong ones still play a prominent if not a very creditable part4 ,thus the medical systems of ,william ,cullen 7#agaj-agij71 and ,john ,brown 7#agce-aghh71 while doing little towards the actual advancement of scientific medicine1 played so conspicuous a part in so wide a field that the ,brunonian system at least must be given some little attention4 ,according to ,brown's theory1 life1 diseases1 and methods of cure are explained by the property of excitability4 ,all exciting powers were supposed to be stimulating1 the apparent debilitating effects of some being due to a deficiency in the amount of stimulus4 ,thus the whole phenomena of life1 health1 as well as disease1 were supposed to consist of stimulus and nothing else4 ,this theory created a great stir in the medical world1 and partisans and opponents sprang up everywhere4 ,in ,italy it was enthusiastically supported2 in ,england it was strongly opposed2 while in ,scotland riots took place between the opposing factions4 ,just why this system should have created any stir1 either for or against it1 is not now apparent4 ,like so many of the other theorists of his century1 ,brown's practical conclusions deduced from his theory 7or perhaps in spite of it7 were generally beneficial to medicine1 and some of them extremely valuable in the treatment of diseases4 ,he first advocated the modern stimulant1 or feeding treatment of fevers1 and first recognized the usefulness of animal soups and beef-tea in certain diseases4 ,,the ,,system ,,of ,,hahnemann ,just at the close of the century there came into prominence the school of homoeopathy1 which was destined to influence the practice of medicine very materially and to outlive all the other eighteenth-century schools4 ,it was founded by ,christian ,samuel ,friedrich ,hahnemann 7#agee-ahdc71 a most remarkable man1 who1 after propounding a theory in his younger days which was at least as reasonable as most of the existing theories1 had the misfortune to outlive his usefulness and lay his doctrine open to ridicule by the unreasonable teachings of his dotage4 ,hahnemann rejected all the teachings of morbid anatomy and pathology as useless in practice1 and propounded his famous similia similibus curantur--that all diseases were to be cured by medicine which in health produced symptoms dynamically similar to the disease under treatment4 ,if a certain medicine produced a headache when given to a healthy person1 then this medicine was indicated in case of headaches1 etc4 ,at the present time such a theory seems crude enough1 but in the latter part of the eighteenth century almost any theory was as good as the ones propounded by ,animists1 ,vitalists1 and other such schools4 ,it certainly had the very commendable feature of introducing simplicity in the use of drugs in place of the complicated prescriptions then in vogue4 ,had ,hahnemann stopped at this point he could not have been held up to the indefensible ridicule that was brought upon him1 with considerable justice1 by his later theories4 ,but he lived onto propound his extraordinary theory of potentiality--that medicines gained strength by being diluted--and his even more extraordinary theory that all chronic diseases are caused either by the itch1 syphilis1 or fig-wart disease1 or are brought on by medicines4 ,at the time that his theory of potentialities was promulgated1 the medical world had gone mad in its administration of huge doses of compound mixtures of drugs1 and any reaction against this was surely an improvement4 ,in short1 no medicine at all was much better than the heaping doses used in common practice2 and hence one advantage1 at least1 of ,hahnemann's methods4 ,stated briefly1 his theory was that if a tincture be reduced to one-fiftieth in strength1 and this again reduced to one-fiftieth1 and this process repeated up to thirty such dilutions1 the potency of such a medicine will be increased by each dilution1 ,hahnemann himself preferring the weakest1 or1 as he would call it1 the strongest dilution4 ,the absurdity of such a theory is apparent when it is understood that long before any drug has been raised to its thirtieth dilution it has been so reduced in quantity that it cannot be weighed1 measured1 or recognized as being present in the solution at all by any means known to chemists4 ,it is but just to modern followers of homoeopathy to say that while most of them advocate small dosage1 they do not necessarily follow the teachings of ,hahnemann in this respect1 believing that the theory of the dose has nothing more to do with the original law of cure than the psora 7itch7 theory has2 and that it was one of the later creations of ,hahnemann's mind4 ,hahnemann's theory that all chronic diseases are derived from either itch1 syphilis1 or fig-wart disease is no longer advocated by his followers1 because it is so easily disproved1 particularly in the case of itch4 ,hahnemann taught that fully three-quarters of all diseases were caused by itch struck in1 and yet it had been demonstrated long before his day1 and can be demonstrated any time1 that itch is simply a local skin disease caused by a small parasite4 ,,jenner ,,and ,,vaccination ,all advances in science have a bearing1 near or remote1 on the welfare of our race2 but it remains to credit to the closing decade of the eighteenth century a discovery which1 in its power of direct and immediate benefit to humanity1 surpasses any other discovery of this or any previous epoch4 ,needless to say1 ,i refer to ,jenner's discovery of the method of preventing smallpox by inoculation with the virus of cow-pox4 ,it detracts nothing from the merit of this discovery to say that the preventive power of accidental inoculation had long been rumored among the peasantry of ,england4 ,such vague1 unavailing half-knowledge is often the forerunner of fruitful discovery4 ,to all intents and purposes ,jenner's discovery was original and unique4 ,nor1 considered as a perfect method1 was it in any sense an accident4 ,it was a triumph of experimental science4 ,the discoverer was no novice in scientific investigation1 but a trained observer1 who had served a long apprenticeship in scientific observation under no less a scientist than the celebrated ,john ,hunter4 ,at the age of twenty-one ,jenner had gone to ,london to pursue his medical studies1 and soon after he proved himself so worthy a pupil that for two years he remained a member of ,hunter's household as his favorite pupil4 ,his taste for science and natural history soon attracted the attention of ,sir ,joseph ,banks1 who intrusted him with the preparation of the zoological specimens brought back by ,captain ,cook's expedition in #agga4 ,he performed this task so well that he was offered the position of naturalist to the second expedition1 but declined it1 preferring to take up the practice of his profession in his native town of ,berkeley4 ,his many accomplishments and genial personality soon made him a favorite both as a physician and in society4 ,he was a good singer1 a fair violinist and flute-player1 and a very successful writer of prose and verse4 ,but with all his professional and social duties he still kept up his scientific investigations1 among other things making some careful observations on the hibernation of hedgehogs at the instigation of ,hunter1 the results of which were laid before the ,royal ,society4 ,he also made quite extensive investigations as to the geological formations and fossils found in his neighborhood4 ,even during his student days with ,hunter he had been much interested in the belief1 current in the rural districts of ,gloucestershire1 of the antagonism between cow-pox and small-pox1 a person having suffered from cow-pox being immuned to small-pox4 ,at various times ,jenner had mentioned the subject to ,hunter1 and he was constantly making inquiries of his fellow-practitioners as to their observations and opinions on the subject4 ,hunter was too fully engrossed in other pursuits to give the matter much serious attention1 however1 and ,jenner's brothers of the profession gave scant credence to the rumors1 although such rumors were common enough4 ,at this time the practice of inoculation for preventing small-pox1 or rather averting the severer forms of the disease1 was widely practised4 ,it was customary1 when there was a mild case of the disease1 to take some of the virus from the patient and inoculate persons who had never had the disease1 producing a similar attack in them4 ,unfortunately there were many objections to this practice4 ,the inoculated patient frequently developed a virulent form of the disease and died2 or if he recovered1 even after a mild attack1 he was likely to be pitted and disfigured4 ,but1 perhaps worst of all1 a patient so inoculated became the source of infection to others1 and it sometimes happened that disastrous epidemics were thus brought about4 ,the case was a most perplexing one1 for the awful scourge of small-pox hung perpetually over the head of every person who had not already suffered and recovered from it4 ,the practice of inoculation was introduced into ,england by ,lady ,mary ,wortley ,montague 7#afij-agfb71 who had seen it practised in the ,east1 and who announced her intention of introducing it into ,england in spite of the doctors4 ,from the fact that certain persons1 usually milkmaids1 who had suffered from cow-pox seemed to be immuned to small-pox1 it would seem a very simple process of deduction to discover that cow-pox inoculation was the solution of the problem of preventing the disease4 ,but there was another form of disease which1 while closely resembling cow-pox and quite generally confounded with it1 did not produce immunity4 ,the confusion of these two forms of the disease had constantly misled investigations as to the possibility of either of them immunizing against smallpox1 and the confusion of these two diseases for a time led ,jenner to question the possibility of doing so4 ,after careful investigations1 however1 he reached the conclusion that there was a difference in the effects of the two diseases1 only one of which produced immunity from small-pox4 ,there is a disease to which the horse1 from his state of domestication1 is frequently subject1 wrote ,jenner1 in his famous paper on vaccination4 ,the farriers call it the grease4 ,it is an inflammation and swelling in the heel1 accompanied at its commencement with small cracks or fissures1 from which issues a limpid fluid possessing properties of a very peculiar kind4 ,this fluid seems capable of generating a disease in the human body 7after it has undergone the modification ,i shall presently speak of7 which bears so strong a resemblance to small-pox that ,i think it highly probable it may be the source of that disease4 ,in this dairy country a great number of cows are kept1 and the office of milking is performed indiscriminately by men and maid servants4 ,one of the former having been appointed to apply dressings to the heels of a horse affected with the malady ,i have mentioned1 and not paying due attention to cleanliness1 incautiously bears his part in milking the cows with some particles of the infectious matter adhering to his fingers4 ,when this is the case it frequently happens that a disease is communicated to the cows1 and from the cows to the dairy-maids1 which spreads through the farm until most of the cattle and domestics feel its unpleasant consequences4 ,this disease has obtained the name of ,cow-,pox4 ,it appears on the nipples of the cows in the form of irregular pustules4 ,at their first appearance they are commonly of a palish blue1 or rather of a color somewhat approaching to livid1 and are surrounded by an inflammation4 ,these pustules1 unless a timely remedy be applied1 frequently degenerate into phagedenic ulcers1 which prove extremely troublesome4 ,the animals become indisposed1 and the secretion of milk is much lessened4 ,inflamed spots now begin to appear on different parts of the hands of the domestics employed in milking1 and sometimes on the wrists1 which run on to suppuration1 first assuming the appearance of the small vesications produced by a burn4 ,most commonly they appear about the joints of the fingers and at their extremities2 but whatever parts are affected1 if the situation will admit the superficial suppurations put on a circular form with their edges more elevated than their centre and of a color distinctly approaching to blue4 ,absorption takes place1 and tumors appear in each axilla4 ,the system becomes affected1 the pulse is quickened2 shiverings1 succeeded by heat1 general lassitude1 and pains about the loins and limbs1 with vomiting1 come on4 ,the head is painful1 and the patient is now and then even affected with delirium4 ,these symptoms1 varying in their degrees of violence1 generally continue from one day to three or four1 leaving ulcerated sores about the hands which1 from the sensibility of the parts1 are very troublesome and commonly heal slowly1 frequently becoming phagedenic1 like those from which they sprang4 ,during the progress of the disease the lips1 nostrils1 eyelids1 and other parts of the body are sometimes affected with sores2 but these evidently arise from their being heedlessly rubbed or scratched by the patient's infected fingers4 ,no eruptions on the skin have followed the decline of the feverish symptoms in any instance that has come under my inspection1 one only excepted1 and in this case a very few appeared on the arms3 they were very minute1 of a vivid red color1 and soon died away without advancing to maturation1 so that ,i cannot determine whether they had any connection with the preceding symptoms4 ,thus the disease makes its progress from the horse 7as ,i conceive7 to the nipple of the cow1 and from the cow to the human subject4 ,morbid matter of various kinds1 when absorbed into the system1 may produce effects in some degree similar2 but what renders the cow-pox virus so extremely singular is that the person that has been thus affected is forever after secure from the infection of small-pox1 neither exposure to the variolous effluvia nor the insertion of the matter into the skin producing this distemper47#b7 ,in #agif ,jenner made his first inoculation with cowpox matter1 and two months later the same subject was inoculated with small-pox matter4 ,but1 as ,jenner had predicted1 no attack of small-pox followed4 ,although fully convinced by this experiment that the case was conclusively proven1 he continued his investigations1 waiting two years before publishing his discovery4 ,then1 fortified by indisputable proofs1 he gave it to the world4 ,the immediate effects of his announcement have probably never been equalled in the history of scientific discovery1 unless1 perhaps1 in the single instance of the discovery of anaesthesia4 ,in ,geneva and ,holland clergymen advocated the practice of vaccination from their pulpits2 in some of the ,latin countries religious processions were formed for receiving vaccination2 ,jenner's birthday was celebrated as a feast in ,germany2 and the first child vaccinated in ,russia was named ,vaccinov and educated at public expense4 ,in six years the discovery had penetrated to the most remote corners of civilization2 it had even reached some savage nations4 ,and in a few years small-pox had fallen from the position of the most dreaded of all diseases to that of being practically the only disease for which a sure and easy preventive was known4 ,honors were showered upon ,jenner from the ,old and the ,new ,world1 and even ,napoleon1 the bitter hater of the ,english1 was among the others who honored his name4 ,on one occasion ,jenner applied to the ,emperor for the release of certain ,englishmen detained in ,france4 ,the petition was about to be rejected when the name of the petitioner was mentioned4 ,ah1 said ,napoleon1 we can refuse nothing to that name6 ,it is difficult for us of to-day clearly to conceive the greatness of ,jenner's triumph1 for we can only vaguely realize what a ruthless and ever-present scourge smallpox had been to all previous generations of men since history began4 ,despite all efforts to check it by medication and by direct inoculation1 it swept now and then over the earth as an all-devastating pestilence1 and year by year it claimed one-tenth of all the beings in ,christendom by death as its average quota of victims4 ,from small-pox and love but few remain free1 ran the old saw4 ,a pitted face was almost as much a matter of course a hundred years ago as a smooth one is to-day4 ,little wonder1 then1 that the world gave eager acceptance to ,jenner's discovery4 ,no urging was needed to induce the majority to give it trial2 passengers on a burning ship do not hold aloof from the life-boats4 ,rich and poor1 high and low1 sought succor in vaccination and blessed the name of their deliverer4 ,of all the great names that were before the world in the closing days of the century1 there was perhaps no other one at once so widely known and so uniformly reverenced as that of the great ,english physician ,edward ,jenner4 ,surely there was no other one that should be recalled with greater gratitude by posterity4 ,,viii4 ,,nineteenth-,,century ,,medicine ,,physical ,,diagnosis ,although ,napoleon ,bonaparte1 ,first ,consul1 was not lacking in self-appreciation1 he probably did not realize that in selecting a physician for his own needs he was markedly influencing the progress of medical science as a whole4 ,yet so strangely are cause and effect adjusted in human affairs that this simple act of the ,first ,consul had that very unexpected effect4 ,for the man chosen was the envoy of a new method in medical practice1 and the fame which came to him through being physician to the ,first ,consul1 and subsequently to the ,emperor1 enabled him to promulgate the method in a way otherwise impracticable4 ,hence the indirect but telling value to medical science of ,napoleon's selection4 ,the physician in question was ,jean ,nicolas de ,corvisart4 ,his novel method was nothing more startling than the now-familiar procedure of tapping the chest of a patient to elicit sounds indicative of diseased tissues within4 ,every one has seen this done commonly enough in our day1 but at the beginning of the century ,corvisart1 and perhaps some of his pupils1 were probably the only physicians in the world who resorted to this simple and useful procedure4 ,hence ,napoleon's surprise when1 on calling in ,corvisart1 after becoming somewhat dissatisfied with his other physicians ,pinel and ,portal1 his physical condition was interrogated in this strange manner4 ,with characteristic shrewdness ,bonaparte saw the utility of the method1 and the physician who thus attempted to substitute scientific method for guess-work in the diagnosis of disease at once found favor in his eyes and was installed as his regular medical adviser4 ,for fifteen years before this ,corvisart had practised percussion1 as the chest-tapping method is called1 without succeeding in convincing the profession of its value4 ,the method itself1 it should be added1 had not originated with ,corvisart1 nor did the ,french physician for a moment claim it as his own4 ,the true originator of the practice was the ,german physician ,avenbrugger1 who published a book about it as early as #agfa4 ,this book had even been translated into ,french1 then the language of international communication everywhere1 by ,roziere de la ,chassagne1 of ,montpellier1 in #aggj2 but no one other than ,corvisart appears to have paid any attention to either original or translation4 ,it was far otherwise1 however1 when ,corvisart translated ,avenbrugger's work anew1 with important additions of his own1 in #ahjh4 ,i know very well how little reputation is allotted to translator and commentators1 writes ,corvisart1 and ,i might easily have elevated myself to the rank of an author if ,i had elaborated anew the doctrine of ,avenbrugger and published an independent work on percussion4 ,in this way1 however1 ,i should have sacrificed the name of ,avenbrugger to my own vanity1 a thing which ,i am unwilling to do4 ,it is he1 and the beautiful invention which of right belongs to him1 that ,i desire to recall to life47#a7 ,by this time a reaction had set in against the metaphysical methods in medicine that had previously been so alluring2 the scientific spirit of the time was making itself felt in medical practice2 and this1 combined with ,corvisart's fame1 brought the method of percussion into immediate and well-deserved popularity4 ,thus was laid the foundation for the method of so-called physical diagnosis1 which is one of the corner-stones of modern medicine4 ,the method of physical diagnosis as practised in our day was by no means completed1 however1 with the work of ,corvisart4 ,percussion alone tells much less than half the story that may be elicited from the organs of the chest by proper interrogation4 ,the remainder of the story can only be learned by applying the ear itself to the chest1 directly or indirectly4 ,simple as this seems1 no one thought of practising it for some years after ,corvisart had shown the value of percussion4 ,then1 in #ahae1 another ,paris physician1 ,rene ,theophile ,hyacinthe ,laennec1 discovered1 almost by accident1 that the sound of the heart-beat could be heard surprisingly through a cylinder of paper held to the ear and against the patient's chest4 ,acting on the hint thus received1 ,laennec substituted a hollow cylinder of wood for the paper1 and found himself provided with an instrument through which not merely heart sounds but murmurs of the lungs in respiration could be heard with almost startling distinctness4 ,the possibility of associating the varying chest sounds with diseased conditions of the organs within appealed to the fertile mind of ,laennec as opening new vistas in therapeutics1 which he determined to enter to the fullest extent practicable4 ,his connection with the hospitals of ,paris gave him full opportunity in this direction1 and his labors of the next few years served not merely to establish the value of the new method as an aid to diagnosis1 but laid the foundation also for the science of morbid anatomy4 ,in #ahai ,laennec published the results of his labors in a work called ,traite d',auscultation ,mediate17#b7 a work which forms one of the landmarks of scientific medicine4 ,by mediate auscultation is meant1 of course1 the interrogation of the chest with the aid of the little instrument already referred to1 an instrument which its originator thought hardly worth naming until various barbarous appellations were applied to it by others1 after which ,laennec decided to call it the stethoscope1 a name which it has ever since retained4 ,in subsequent years the form of the stethoscope1 as usually employed1 was modified and its value augmented by a binauricular attachment1 and in very recent years a further improvement has been made through application of the principle of the telephone2 but the essentials of auscultation with the stethoscope were established in much detail by ,laennec1 and the honor must always be his of thus taking one of the longest single steps by which practical medicine has in our century acquired the right to be considered a rational science4 ,laennec's efforts cost him his life1 for he died in #ahbf of a lung disease acquired in the course of his hospital practice2 but even before this his fame was universal1 and the value of his method had been recognized all over the world4 ,not long after1 in #ahbh1 yet another ,french physician1 ,piorry1 perfected the method of percussion by introducing the custom of tapping1 not the chest directly1 but the finger or a small metal or hard-rubber plate held against the chest-mediate percussion1 in short4 ,this perfected the methods of physical diagnosis of diseases of the chest in all essentials2 and from that day till this percussion and auscultation have held an unquestioned place in the regular armamentarium of the physician4 ,coupled with the new method of physical diagnosis in the effort to substitute knowledge for guess-work came the studies of the experimental physiologists--in particular1 ,marshall ,hall in ,england and ,francois ,magendie in ,france2 and the joint efforts of these various workers led presently to the abandonment of those severe and often irrational depletive methods--blood-letting and the like--that had previously dominated medical practice4 ,to this end also the statistical method1 introduced by ,louis and his followers1 largely contributed2 and by the close of the first third of our century the idea was gaining ground that the province of therapeutics is to aid nature in combating disease1 and that this may often be accomplished better by simple means than by the heroic measures hitherto thought necessary4 ,in a word1 scientific empiricism was beginning to gain a hearing in medicine as against the metaphysical preconceptions of the earlier generations4 ,,parasitic ,,diseases ,i have just adverted to the fact that ,napoleon ,bonaparte1 as ,first ,consul and as ,emperor1 was the victim of a malady which caused him to seek the advice of the most distinguished physicians of ,paris4 ,it is a little shocking to modern sensibilities to read that these physicians1 except ,corvisart1 diagnosed the distinguished patient's malady as gale repercutee--that is to say1 in idiomatic ,english1 the itch struck in4 ,it is hardly necessary to say that no physician of today would make so inconsiderate a diagnosis in the case of a royal patient4 ,if by any chance a distinguished patient were afflicted with the itch1 the sagacious physician would carefully hide the fact behind circumlocutions and proceed to eradicate the disease with all despatch4 ,that the physicians of ,napoleon did otherwise is evidence that at the beginning of the century the disease in question enjoyed a very different status4 ,at that time itch1 instead of being a most plebeian malady1 was1 so to say1 a court disease4 ,it enjoyed a circulation1 in high circles and in low1 that modern therapeutics has quite denied it2 and the physicians of the time gave it a fictitious added importance by ascribing to its influence the existence of almost any obscure malady that came under their observation4 ,long after ,napoleon's time gale continued to hold this proud distinction4 ,for example1 the imaginative ,dr4 ,hahnemann did not hesitate to affirm1 as a positive maxim1 that three-fourths of all the ills that flesh is heir to were in reality nothing but various forms of gale repercutee4 ,all of which goes to show how easy it may be for a masked pretender to impose on credulous humanity1 for nothing is more clearly established in modern knowledge than the fact that gale repercutee was simply a name to hide a profound ignorance2 no such disease exists or ever did exist4 ,gale itself is a sufficiently tangible reality1 to be sure1 but it is a purely local disease of the skin1 due to a perfectly definite cause1 and the dire internal conditions formerly ascribed to it have really no causal connection with it whatever4 ,this definite cause1 as every one nowadays knows1 is nothing more or less than a microscopic insect which has found lodgment on the skin1 and has burrowed and made itself at home there4 ,kill that insect and the disease is no more2 hence it has come to be an axiom with the modern physician that the itch is one of the three or four diseases that he positively is able to cure1 and that very speedily4 ,but it was far otherwise with the physicians of the first third of our century1 because to them the cause of the disease was an absolute mystery4 ,it is true that here and there a physician had claimed to find an insect lodged in the skin of a sufferer from itch1 and two or three times the claim had been made that this was the cause of the malady1 but such views were quite ignored by the general profession1 and in #ahcc it was stated in an authoritative medical treatise that the cause of gale is absolutely unknown4 ,but even at this time1 as it curiously happened1 there were certain ignorant laymen who had attained to a bit of medical knowledge that was withheld from the inner circles of the profession4 ,as the peasantry of ,england before ,jenner had known of the curative value of cow-pox over small-pox1 so the peasant women of ,poland had learned that the annoying skin disease from which they suffered was caused by an almost invisible insect1 and1 furthermore1 had acquired the trick of dislodging the pestiferous little creature with the point of a needle4 ,from them a youth of the country1 ,f4 ,renucci by name1 learned the open secret4 ,he conveyed it to ,paris when he went there to study medicine1 and in #ahcd demonstrated it to his master ,alibert4 ,this physician1 at first sceptical1 soon was convinced1 and gave out the discovery to the medical world with an authority that led to early acceptance4 ,now the importance of all this1 in the present connection1 is not at all that it gave the clew to the method of cure of a single disease4 ,what makes the discovery epochal is the fact that it dropped a brand-new idea into the medical ranks--an idea destined1 in the long-run1 to prove itself a veritable bomb--the idea1 namely1 that a minute and quite unsuspected animal parasite may be the cause of a well-known1 widely prevalent1 and important human disease4 ,of course the full force of this idea could only be appreciated in the light of later knowledge2 but even at the time of its coming it sufficed to give a great impetus to that new medical knowledge1 based on microscopical studies1 which had but recently been made accessible by the inventions of the lens-makers4 ,the new knowledge clarified one very turbid medical pool and pointed the way to the clarification of many others4 ,almost at the same time that the ,polish medical student was demonstrating the itch mite in ,paris1 it chanced1 curiously enough1 that another medical student1 this time an ,englishman1 made an analogous discovery of perhaps even greater importance4 ,indeed1 this ,english discovery in its initial stages slightly antedated the other1 for it was in #ahcc that the student in question1 ,james ,paget1 interne in ,st4 ,bartholomew's ,hospital1 ,london1 while dissecting the muscular tissues of a human subject1 found little specks of extraneous matter1 which1 when taken to the professor of comparative anatomy1 ,richard ,owen1 were ascertained1 with the aid of the microscope1 to be the cocoon of a minute and hitherto unknown insect4 ,owen named the insect ,trichina spiralis4 ,after the discovery was published it transpired that similar specks had been observed by several earlier investigators1 but no one had previously suspected or1 at any rate1 demonstrated their nature4 ,nor was the full story of the trichina made out for a long time after ,owen's discovery4 ,it was not till #ahdg that the ,american anatomist ,dr4 ,joseph ,leidy found the cysts of trichina in the tissues of pork2 and another decade or so elapsed after that before ,german workers1 chief among whom were ,leuckart1 ,virchow1 and ,zenker1 proved that the parasite gets into the human system through ingestion of infected pork1 and that it causes a definite set of symptoms of disease which hitherto had been mistaken for rheumatism1 typhoid fever1 and other maladies4 ,then the medical world was agog for a time over the subject of trichinosis2 government inspection of pork was established in some parts of ,germany2 ,american pork was excluded altogether from ,france2 and the whole subject thus came prominently to public attention4 ,but important as the trichina parasite proved on its own account in the end1 its greatest importance1 after all1 was in the share it played in directing attention at the time of its discovery in #ahcc to the subject of microscopic parasites in general4 ,the decade that followed that discovery was a time of great activity in the study of microscopic organisms and microscopic tissues1 and such men as ,ehrenberg and ,henle and ,bory ,saint-,vincent and ,kolliker and ,rokitansky and ,remak and ,dujardin were widening the bounds of knowledge of this new subject with details that cannot be more than referred to here4 ,but the crowning achievement of the period in this direction was the discovery made by the ,german1 ,j4 ,l4 ,schoenlein1 in #ahci1 that a very common and most distressing disease of the scalp1 known as favus1 is really due to the presence and growth on the scalp of a vegetable organism of microscopic size4 ,thus it was made clear that not merely animal but also vegetable organisms of obscure1 microscopic species have causal relations to the diseases with which mankind is afflicted4 ,this knowledge of the parasites was another long step in the direction of scientific medical knowledge2 but the heights to which this knowledge led were not to be scaled1 or even recognized1 until another generation of workers had entered the field4 ,,painless ,,surgery ,meantime1 in quite another field of medicine1 events were developing which led presently to a revelation of greater immediate importance to humanity than any other discovery that had come in the century1 perhaps in any field of science whatever4 ,this was the discovery of the pain-dispelling power of the vapor of sulphuric ether inhaled by a patient undergoing a surgical operation4 ,this discovery came solely out of ,america1 and it stands curiously isolated1 since apparently no minds in any other country were trending towards it even vaguely4 ,davy1 in ,england1 had indeed originated the method of medication by inhalation1 and earned out some most interesting experiments fifty years earlier1 and it was doubtless his experiments with nitrous oxide gas that gave the clew to one of the ,american investigators2 but this was the sole contribution of preceding generations to the subject1 and since the beginning of the century1 when ,davy turned his attention to other matters1 no one had made the slightest advance along the same line until an ,american dentist renewed the investigation4 ,in view of the sequel1 ,davy's experiments merit full attention4 ,here is his own account of them1 as written in #agii3 ,immediately after a journey of one hundred and twenty-six miles1 in which ,i had no sleep the preceding night1 being much exhausted1 ,i respired seven quarts of nitrous oxide gas for near three minutes4 ,it produced the usual pleasurable effects and slight muscular motion4 ,i continued exhilarated for some minutes afterwards1 but in half an hour found myself neither more nor less exhausted than before the experiment4 ,i had a great propensity to sleep4 ,to ascertain with certainty whether the more extensive action of nitrous oxide compatible with life was capable of producing debility1 ,i resolved to breathe the gas for such a time1 and in such quantities1 as to produce excitement equal in duration and superior in intensity to that occasioned by high intoxication from opium or alcohol4 ,to habituate myself to the excitement1 and to carry it on gradually1 on ,december #bfth ,i was enclosed in an air-tight breathing-box1 of the capacity of about nine and one-half cubic feet1 in the presence of ,dr4 ,kinglake4 ,after ,i had taken a situation in which ,i could by means of a curved thermometer inserted under the arm1 and a stop-watch1 ascertain the alterations in my pulse and animal heat1 twenty quarts of nitrous oxide were thrown into the box4 ,for three minutes ,i experienced no alteration in my sensations1 though immediately after the introduction of the nitrous oxide the smell and taste of it were very evident4 ,in four minutes ,i began to feel a slight glow in the cheeks and a generally diffused warmth over the chest1 though the temperature of the box was not quite #ej degrees4444 ,in twenty-five minutes the animal heat was #ajj degrees1 pulse #abd4 ,in thirty minutes twenty quarts more of gas were introduced4 ,my sensations were now pleasant2 ,i had a generally diffused warmth without the slightest moisture of the skin1 a sense of exhilaration similar to that produced by a small dose of wine1 and a disposition to muscular motion and to merriment4 ,in three-quarters of an hour the pulse was #ajd and the animal heat not #ii4e degrees1 the temperature of the chamber #fd degrees4 ,the pleasurable feelings continued to increase1 the pulse became fuller and slower1 till in about an hour it was #hh1 when the animal heat was #ii degrees4 ,twenty quarts more of air were admitted4 ,i had now a great disposition to laugh1 luminous points seemed frequently to pass before my eyes1 my hearing was certainly more acute1 and ,i felt a pleasant lightness and power of exertion in my muscles4 ,in a short time the symptoms became stationary2 breathing was rather oppressed1 and on account of the great desire for action rest was painful4 ,i now came out of the box1 having been in precisely an hour and a quarter4 ,the moment after ,i began to respire twenty quarts of unmingled nitrous oxide4 ,a thrilling extending from the chest to the extremities was almost immediately produced4 ,i felt a sense of tangible extension highly pleasurable in every limb2 my visible impressions were dazzling and apparently magnified1 ,i heard distinctly every sound in the room1 and was perfectly aware of my situation4 ,by degrees1 as the pleasurable sensations increased1 ,i lost all connection with external things2 trains of vivid visible images rapidly passed through my mind and were connected with words in such a manner as to produce perceptions perfectly novel4 ,i existed in a world of newly connected and newly modified ideas4 ,i theorized2 ,i imagined that ,i made discoveries4 ,when ,i was awakened from this semi-delirious trance by ,dr4 ,kinglake1 who took the bag from my mouth1 indignation and pride were the first feelings produced by the sight of persons about me4 ,my emotions were enthusiastic and sublime2 and for a minute ,i walked about the room perfectly regardless of what was said to me4 ,as ,i recovered my former state of mind1 ,i felt an inclination to communicate the discoveries ,i had made during the experiment4 ,i endeavored to recall the ideas--they were feeble and indistinct2 one collection of terms1 however1 presented itself1 and1 with most intense belief and prophetic manner1 ,i exclaimed to ,dr4 ,kinglake1 ',nothing exists but thoughts6--the universe is composed of impressions1 ideas1 pleasures1 and pains4' 7#c7 ,from this account we see that ,davy has anaesthetized himself to a point where consciousness of surroundings was lost1 but not past the stage of exhilaration4 ,had ,dr4 ,kinglake allowed the inhaling-bag to remain in ,davy's mouth for a few moments longer complete insensibility would have followed4 ,as it was1 ,davy appears to have realized that sensibility was dulled1 for he adds this illuminative suggestion3 ,as nitrous oxide in its extensive operation appears capable of destroying physical pain1 it may probably be used with advantage during surgical operations in which no great effusion of blood takes place47#d7 ,unfortunately no one took advantage of this suggestion at the time1 and ,davy himself became interested in other fields of science and never returned to his physiological studies1 thus barely missing one of the greatest discoveries in the entire field of science4 ,in the generation that followed no one seems to have thought of putting ,davy's suggestion to the test1 and the surgeons of ,europe had acknowledged with one accord that all hope of finding a means to render operations painless must be utterly abandoned--that the surgeon's knife must ever remain a synonym for slow and indescribable torture4 ,by an odd coincidence it chanced that ,sir ,benjamin ,brodie1 the acknowledged leader of ,english surgeons1 had publicly expressed this as his deliberate though regretted opinion at a time when the quest which he considered futile had already led to the most brilliant success in ,america1 and while the announcement of the discovery1 which then had no transatlantic cable to convey it1 was actually on its way to the ,old ,world4 ,the ,american dentist just referred to1 who was1 with one exception to be noted presently1 the first man in the world to conceive that the administration of a definite drug might render a surgical operation painless and to give the belief application was ,dr4 ,horace ,wells1 of ,hartford1 ,connecticut4 ,the drug with which he experimented was nitrous oxide--the same that ,davy had used2 the operation that he rendered painless was no more important than the extraction of a tooth--yet it sufficed to mark a principle2 the year of the experiment was #ahdd4 ,the experiments of ,dr4 ,wells1 however1 though important1 were not sufficiently demonstrative to bring the matter prominently to the attention of the medical world4 ,the drug with which he experimented proved not always reliable1 and he himself seems ultimately to have given the matter up1 or at least to have relaxed his efforts4 ,but meantime a friend1 to whom he had communicated his belief and expectations1 took the matter up1 and with unremitting zeal carried forward experiments that were destined to lead to more tangible results4 ,this friend was another dentist1 ,dr4 ,w4 ,t4 ,g4 ,morton1 of ,boston1 then a young man full of youthful energy and enthusiasm4 ,he seems to have felt that the drug with which ,wells had experimented was not the most practicable one for the purpose1 and so for several months he experimented with other allied drugs1 until finally he hit upon sulphuric ether1 and with this was able to make experiments upon animals1 and then upon patients in the dental chair1 that seemed to him absolutely demonstrative4 ,full of eager enthusiasm1 and absolutely confident of his results1 he at once went to ,dr4 ,j4 ,c4 ,warren1 one of the foremost surgeons of ,boston1 and asked permission to test his discovery decisively on one of the patients at the ,boston ,hospital during a severe operation4 ,the request was granted2 the test was made on ,october #af1 #ahdf1 in the presence of several of the foremost surgeons of the city and of a body of medical students4 ,the patient slept quietly while the surgeon's knife was plied1 and awoke to astonished comprehension that the ordeal was over4 ,the impossible1 the miraculous1 had been accomplished47#e7 ,swiftly as steam could carry it--slowly enough we should think it to-day--the news was heralded to all the world4 ,it was received in ,europe with incredulity1 which vanished before repeated experiments4 ,surgeons were loath to believe that ether1 a drug that had long held a place in the subordinate armamentarium of the physician1 could accomplish such a miracle4 ,but scepticism vanished before the tests which any surgeon might make1 and which surgeons all over the world did make within the next few weeks4 ,then there came a lingering outcry from a few surgeons1 notably some of the ,parisians1 that the shock of pain was beneficial to the patient1 hence that anaesthesia--as ,dr4 ,oliver ,wendell ,holmes had christened the new method--was a procedure not to be advised4 ,then1 too1 there came a hue-and-cry from many a pulpit that pain was ,god-given1 and hence1 on moral grounds1 to be clung to rather than renounced4 ,but the outcry of the antediluvians of both hospital and pulpit quickly received its quietus2 for soon it was clear that the patient who did not suffer the shock of pain during an operation rallied better than the one who did so suffer1 while all humanity outside the pulpit cried shame to the spirit that would doom mankind to suffer needless agony4 ,and so within a few months after that initial operation at the ,boston ,hospital in #ahdf1 ether had made good its conquest of pain throughout the civilized world4 ,only by the most active use of the imagination can we of this present day realize the full meaning of that victory4 ,it remains to be added that in the subsequent bickerings over the discovery--such bickerings as follow every great advance--two other names came into prominent notice as sharers in the glory of the new method4 ,both these were ,americans--the one1 ,dr4 ,charles ,t4 ,jackson1 of ,boston2 the other1 ,dr4 ,crawford ,w4 ,long1 of ,alabama4 ,as to ,dr4 ,jackson1 it is sufficient to say that he seems to have had some vague inkling of the peculiar properties of ether before ,morton's discovery4 ,he even suggested the use of this drug to ,morton1 not knowing that ,morton had already tried it2 but this is the full measure of his association with the discovery4 ,hence it is clear that ,jackson's claim to equal share with ,morton in the discovery was unwarranted1 not to say absurd4 ,dr4 ,long's association with the matter was far different and altogether honorable4 ,by one of those coincidences so common in the history of discovery1 he was experimenting with ether as a pain-destroyer simultaneously with ,morton1 though neither so much as knew of the existence of the other4 ,while a medical student he had once inhaled ether for the intoxicant effects1 as other medical students were wont to do1 and when partially under influence of the drug he had noticed that a chance blow to his shins was painless4 ,this gave him the idea that ether might be used in surgical operations2 and in subsequent years1 in the course of his practice in a small ,georgia town1 he put the idea into successful execution4 ,there appears to be no doubt whatever that he performed successful minor operations under ether some two or three years before ,morton's final demonstration2 hence that the merit of first using the drug1 or indeed any drug1 in this way belongs to him4 ,but1 unfortunately1 ,dr4 ,long did not quite trust the evidence of his own experiments4 ,just at that time the medical journals were full of accounts of experiments in which painless operations were said to be performed through practice of hypnotism1 and ,dr4 ,long feared that his own success might be due to an incidental hypnotic influence rather than to the drug4 ,hence he delayed announcing his apparent discovery until he should have opportunity for further tests--and opportunities did not come every day to the country practitioner4 ,and while he waited1 ,morton anticipated him1 and the discovery was made known to the world without his aid4 ,it was a true scientific caution that actuated ,dr4 ,long to this delay1 but the caution cost him the credit1 which might otherwise have been his1 of giving to the world one of the greatest blessings--dare we not1 perhaps1 say the very greatest8--that science has ever conferred upon humanity4 ,a few months after the use of ether became general1 the ,scotch surgeon ,sir ,j4 ,y4 ,simpson7#f7 discovered that another drug1 chloroform1 could be administered with similar effects2 that it would1 indeed1 in many cases produce anaesthesia more advantageously even than ether4 ,from that day till this surgeons have been more or less divided in opinion as to the relative merits of the two drugs2 but this fact1 of course1 has no bearing whatever upon the merit of the first discovery of the method of anaesthesia4 ,even had some other drug subsequently quite banished ether1 the honor of the discovery of the beneficent method of anaesthesia would have been in no wise invalidated4 ,and despite all cavillings1 it is unequivocally established that the man who gave that method to the world was ,william ,t4 ,g4 ,morton4 ,,pasteur ,,and ,,the ,,germ ,,theory ,,of ,,disease ,the discovery of the anaesthetic power of drugs was destined presently1 in addition to its direct beneficences1 to aid greatly in the progress of scientific medicine1 by facilitating those experimental studies of animals from which1 before the day of anaesthesia1 many humane physicians were withheld1 and which in recent years have led to discoveries of such inestimable value to humanity4 ,but for the moment this possibility was quite overshadowed by the direct benefits of anaesthesia1 and the long strides that were taken in scientific medicine during the first fifteen years after ,morton's discovery were mainly independent of such aid4 ,these steps were taken1 indeed1 in a field that at first glance might seem to have a very slight connection with medicine4 ,moreover1 the chief worker in the field was not himself a physician4 ,he was a chemist1 and the work in which he was now engaged was the study of alcoholic fermentation in vinous liquors4 ,yet these studies paved the way for the most important advances that medicine has made in any century towards the plane of true science2 and to this man more than to any other single individual--it might almost be said more than to all other individuals--was due this wonderful advance4 ,it is almost superfluous to add that the name of this marvellous chemist was ,louis ,pasteur4 ,the studies of fermentation which ,pasteur entered upon in #ahed were aimed at the solution of a controversy that had been waging in the scientific world with varying degrees of activity for a quarter of a century4 ,back in the thirties1 in the day of the early enthusiasm over the perfected microscope1 there had arisen a new interest in the minute forms of life which ,leeuwenhoek and some of the other early workers with the lens had first described1 and which now were shown to be of almost universal prevalence4 ,these minute organisms had been studied more or less by a host of observers1 but in particular by the ,frenchman ,cagniard ,latour and the ,german of cell-theory fame1 ,theodor ,schwann4 ,these men1 working independently1 had reached the conclusion1 about #ahcg1 that the micro-organisms play a vastly more important role in the economy of nature than any one previously had supposed4 ,they held1 for example1 that the minute specks which largely make up the substance of yeast are living vegetable organisms1 and that the growth of these organisms is the cause of the important and familiar process of fermentation4 ,they even came to hold1 at least tentatively1 the opinion that the somewhat similar micro-organisms to be found in all putrefying matter1 animal or vegetable1 had a causal relation to the process of putrefaction4 ,this view1 particularly as to the nature of putrefaction1 was expressed even more outspokenly a little later by the ,french botanist ,turpin4 ,views so supported naturally gained a following2 it was equally natural that so radical an innovation should be antagonized4 ,in this case it chanced that one of the most dominating scientific minds of the time1 that of ,liebig1 took a firm and aggressive stand against the new doctrine4 ,in #ahci he promulgated his famous doctrine of fermentation1 in which he stood out firmly against any vitalistic explanation of the phenomena1 alleging that the presence of micro-organisms in fermenting and putrefying substances was merely incidental1 and in no sense causal4 ,this opinion of the great ,german chemist was in a measure substantiated by experiments of his compatriot ,helmholtz1 whose earlier experiments confirmed1 but later ones contradicted1 the observations of ,schwann1 and this combined authority gave the vitalistic conception a blow from which it had not rallied at the time when ,pasteur entered the field4 ,indeed1 it was currently regarded as settled that the early students of the subject had vastly over-estimated the importance of micro-organisms4 ,and so it came as a new revelation to the generality of scientists of the time1 when1 in #aheg and the succeeding half-decade1 ,pasteur published the results of his researches1 in which the question had been put to a series of altogether new tests1 and brought to unequivocal demonstration4 ,he proved that the micro-organisms do all that his most imaginative predecessors had suspected1 and more4 ,without them1 he proved1 there would be no fermentation1 no putrefaction--no decay of any tissues1 except by the slow process of oxidation4 ,it is the microscopic yeast-plant which1 by seizing on certain atoms of the molecule1 liberates the remaining atoms in the form of carbonic-acid and alcohol1 thus effecting fermentation2 it is another microscopic plant--a bacterium1 as ,devaine had christened it--which in a similar way effects the destruction of organic molecules1 producing the condition which we call putrefaction4 ,pasteur showed1 to the amazement of biologists1 that there are certain forms of these bacteria which secure the oxygen which all organic life requires1 not from the air1 but by breaking up unstable molecules in which oxygen is combined2 that putrefaction1 in short1 has its foundation in the activities of these so-called anaerobic bacteria4 ,in a word1 ,pasteur showed that all the many familiar processes of the decay of organic tissues are1 in effect1 forms of fermentation1 and would not take place at all except for the presence of the living micro-organisms4 ,a piece of meat1 for example1 suspended in an atmosphere free from germs1 will dry up gradually1 without the slightest sign of putrefaction1 regardless of the temperature or other conditions to which it may have been subjected4 ,let us witness one or two series of these experiments as presented by ,pasteur himself in one of his numerous papers before the ,academy of ,sciences4 ,,experiments ,,with ,,grape ,,sugar ,in the course of the discussion which took place before the ,academy upon the subject of the generation of ferments properly so-called1 there was a good deal said about that of wine1 the oldest fermentation known4 ,on this account ,i decided to disprove the theory of ,m4 ,fremy by a decisive experiment bearing solely upon the juice of grapes4 ,i prepared forty flasks of a capacity of from two hundred and fifty to three hundred cubic centimetres and filled them half full with filtered grape-must1 perfectly clear1 and which1 as is the case of all acidulated liquids that have been boiled for a few seconds1 remains uncontaminated although the curved neck of the flask containing them remain constantly open during several months or years4 ,in a small quantity of water ,i washed a part of a bunch of grapes1 the grapes and the stalks together1 and the stalks separately4 ,this washing was easily done by means of a small badger's-hair brush4 ,the washing-water collected the dust upon the surface of the grapes and the stalks1 and it was easily shown under the microscope that this water held in suspension a multitude of minute organisms closely resembling either fungoid spores1 or those of alcoholic ,yeast1 or those of ,mycoderma vini1 etc4 ,this being done1 ten of the forty flasks were preserved for reference2 in ten of the remainder1 through the straight tube attached to each1 some drops of the washing-water were introduced2 in a third series of ten flasks a few drops of the same liquid were placed after it had been boiled2 and1 finally1 in the ten remaining flasks were placed some drops of grape-juice taken from the inside of a perfect fruit4 ,in order to carry out this experiment1 the straight tube of each flask was drawn out into a fine and firm point in the lamp1 and then curved4 ,this fine and closed point was filed round near the end and inserted into the grape while resting upon some hard substance4 ,when the point was felt to touch the support of the grape it was by a slight pressure broken off at the point file mark4 ,then1 if care had been taken to create a slight vacuum in the flask1 a drop of the juice of the grape got into it1 the filed point was withdrawn1 and the aperture immediately closed in the alcohol lamp4 ,this decreased pressure of the atmosphere in the flask was obtained by the following means3 ,after warming the sides of the flask either in the hands or in the lamp-flame1 thus causing a small quantity of air to be driven out of the end of the curved neck1 this end was closed in the lamp4 ,after the flask was cooled1 there was a tendency to suck in the drop of grape-juice in the manner just described4 ,the drop of grape-juice which enters into the flask by this suction ordinarily remains in the curved part of the tube1 so that to mix it with the must it was necessary to incline the flask so as to bring the must into contact with the juice and then replace the flask in its normal position4 ,the four series of comparative experiments produced the following results3 ,the first ten flasks containing the grape-must boiled in pure air did not show the production of any organism4 ,the grape-must could possibly remain in them for an indefinite number of years4 ,those in the second series1 containing the water in which the grapes had been washed separately and together1 showed without exception an alcoholic fermentation which in several cases began to appear at the end of forty-eight hours when the experiment took place at ordinary summer temperature4 ,at the same time that the yeast appeared1 in the form of white traces1 which little by little united themselves in the form of a deposit on the sides of all the flasks1 there were seen to form little flakes of ,mycellium1 often as a single fungoid growth or in combination1 these fungoid growths being quite independent of the must or of any alcoholic yeast4 ,often1 also1 the ,mycoderma vini appeared after some days upon the surface of the liquid4 ,the ,vibria and the lactic ferments properly so called did not appear on account of the nature of the liquid4 ,the third series of flasks1 the washing-water in which had been previously boiled1 remained unchanged1 as in the first series4 ,those of the fourth series1 in which was the juice of the interior of the grapes1 remained equally free from change1 although ,i was not always able1 on account of the delicacy of the experiment1 to eliminate every chance of error4 ,these experiments cannot leave the least doubt in the mind as to the following facts3 ,grape-must1 after heating1 never ferments on contact with the air1 when the air has been deprived of the germs which it ordinarily holds in a state of suspension4 ,the boiled grape-must ferments when there is introduced into it a very small quantity of water in which the surface of the grapes or their stalks have been washed4 ,the grape-must does not ferment when this washing-water has been boiled and afterwards cooled4 ,the grape-must does not ferment when there is added to it a small quantity of the juice of the inside of the grape4 ,the yeast1 therefore1 which causes the fermentation of the grapes in the vintage-tub comes from the outside and not from the inside of the grapes4 ,thus is destroyed the hypothesis of ,,mm4 ,trecol and ,fremy1 who surmised that the albuminous matter transformed itself into yeast on account of the vital germs which were natural to it4 ,with greater reason1 therefore1 there is no longer any question of the theory of ,liebig of the transformation of albuminoid matter into ferments on account of the oxidation4 ,,foreign ,,organisms ,,and ,,the ,,wort ,,of ,,beer ,the method which ,i have just followed1 ,pasteur continues1 in order to show that there exists a correlation between the diseases of beer and certain microscopic organisms leaves no room for doubt1 it seems to me1 in regard to the principles ,i am expounding4 ,every time that the microscope reveals in the leaven1 and especially in the active yeast1 the production of organisms foreign to the alcoholic yeast properly so called1 the flavor of the beer leaves something to be desired1 much or little1 according to the abundance and the character of these little germs4 ,moreover1 when a finished beer of good quality loses after a time its agreeable flavor and becomes sour1 it can be easily shown that the alcoholic yeast deposited in the bottles or the casks1 although originally pure1 at least in appearance1 is found to be contaminated gradually with these filiform or other ferments4 ,all this can be deduced from the facts already given1 but some critics may perhaps declare that these foreign ferments are the consequences of the diseased condition1 itself produced by unknown causes4 ,although this gratuitous hypothesis may be difficult to uphold1 ,i will endeavor to corroborate the preceding observations by a clearer method of investigation4 ,this consists in showing that the beer never has any unpleasant taste in all cases when the alcoholic ferment properly so called is not mixed with foreign ferments2 that it is the same in the case of wort1 and that wort1 liable to changes as it is1 can be preserved unaltered if it is kept from those microscopic parasites which find in it a suitable nourishment and a field for growth4 ,the employment of this second method has1 moreover1 the advantage of proving with certainty the proposition that ,i advanced at first--namely1 that the germs of these organisms are derived from the dust of the atmosphere1 carried about and deposited upon all objects1 or scattered over the utensils and the materials used in a brewery-materials naturally charged with microscopic germs1 and which the various operations in the store-rooms and the malt-house may multiply indefinitely4 ,let us take a glass flask with a long neck of from two hundred and fifty to three hundred cubic centimetres capacity1 and place in it some wort1 with or without hops1 and then in the flame of a lamp draw out the neck of the flask to a fine point1 afterwards heating the liquid until the steam comes out of the end of the neck4 ,it can then be allowed to cool without any other precautions2 but for additional safety there can be introduced into the little point a small wad of asbestos at the moment that the flame is withdrawn from beneath the flask4 ,before thus placing the asbestos it also can be passed through the flame1 as well as after it has been put into the end of the tube4 ,the air which then first re-enters the flask will thus come into contact with the heated glass and the heated liquid1 so as to destroy the vitality of any dust germs that may exist in the air4 ,the air itself will re-enter very gradually1 and slowly enough to enable any dust to be taken up by the drop of water which the air forces up the curvature of the tube4 ,ultimately the tube will be dry1 but the re-entering of the air will be so slow that the particles of dust will fall upon the sides of the tube4 ,the experiments show that with this kind of vessel1 allowing free communication with the air1 and the dust not being allowed to enter1 the dust will not enter at all events for a period of ten or twelve years1 which has been the longest period devoted to these trials2 and the liquid1 if it were naturally limpid1 will not be in the least polluted neither on its surface nor in its mass1 although the outside of the flask may become thickly coated with dust4 ,this is a most irrefutable proof of the impossibility of dust getting inside the flask4 ,the wort thus prepared remains uncontaminated indefinitely1 in spite of its susceptibility to change when exposed to the air under conditions which allow it to gather the dusty particles which float in the atmosphere4 ,it is the same in the case of urine1 beef-tea1 and grape-must1 and generally with all those putrefactable and fermentable liquids which have the property when heated to boiling-point of destroying the vitality of dust germs47#g7 ,there was nothing in these studies bearing directly upon the question of animal diseases1 yet before they were finished they had stimulated progress in more than one field of pathology4 ,at the very outset they sufficed to start afresh the inquiry as to the role played by micro-organisms in disease4 ,in particular they led the ,french physician ,devaine to return to some interrupted studies which he had made ten years before in reference to the animal disease called anthrax1 or splenic fever1 a disease that cost the farmers of ,europe millions of francs annually through loss of sheep and cattle4 ,in #ahej ,devaine had seen multitudes of bacteria in the blood of animals who had died of anthrax1 but he did not at that time think of them as having a causal relation to the disease4 ,now1 however1 in #ahfc1 stimulated by ,pasteur's new revelations regarding the power of bacteria1 he returned to the subject1 and soon became convinced1 through experiments by means of inoculation1 that the microscopic organisms he had discovered were the veritable and the sole cause of the infectious disease anthrax4 ,the publication of this belief in #ahfc aroused a furor of controversy4 ,that a microscopic vegetable could cause a virulent systemic disease was an idea altogether too startling to be accepted in a day1 and the generality of biologists and physicians demanded more convincing proofs than ,devaine as yet was able to offer4 ,naturally a host of other investigators all over the world entered the field4 ,foremost among these was the ,german ,dr4 ,robert ,koch1 who soon corroborated all that ,devaine had observed1 and carried the experiments further in the direction of the cultivation of successive generations of the bacteria in artificial media1 inoculations being made from such pure cultures of the eighth generation1 with the astonishing result that animals thus inoculated succumbed to the disease4 ,such experiments seem demonstrative1 yet the world was unconvinced1 and in #ahgf1 while the controversy was still at its height1 ,pasteur was prevailed upon to take the matter in hand4 ,the great chemist was becoming more and more exclusively a biologist as the years passed1 and in recent years his famous studies of the silk-worm diseases1 which he proved due to bacterial infection1 and of the question of spontaneous generation1 had given him unequalled resources in microscopical technique4 ,and so when1 with the aid of his laboratory associates ,duclaux and ,chamberland and ,roux1 he took up the mooted anthrax question the scientific world awaited the issue with bated breath4 ,and when1 in #ahgg1 ,pasteur was ready to report on his studies of anthrax1 he came forward with such a wealth of demonstrative experiments--experiments the rigid accuracy of which no one would for a moment think of questioning--going to prove the bacterial origin of anthrax1 that scepticism was at last quieted for all time to come4 ,henceforth no one could doubt that the contagious disease anthrax is due exclusively to the introduction into an animal's system of a specific germ--a microscopic plant--which develops there4 ,and no logical mind could have a reasonable doubt that what is proved true of one infectious disease would some day be proved true also of other1 perhaps of all1 forms of infectious maladies4 ,hitherto the cause of contagion1 by which certain maladies spread from individual to individual1 had been a total mystery1 quite unillumined by the vague terms miasm1 humor1 virus1 and the like cloaks of ignorance4 ,here and there a prophet of science1 as ,schwann and ,henle1 had guessed the secret2 but guessing1 in science1 is far enough from knowing4 ,now1 for the first time1 the world ,,knew1 and medicine had taken another gigantic stride towards the heights of exact science4 ,,lister ,,and ,,antiseptic ,,surgery ,meantime1 in a different though allied field of medicine there had been a complementary growth that led to immediate results of even more practical importance4 ,i mean the theory and practice of antisepsis in surgery4 ,this advance1 like the other1 came as a direct outgrowth of ,pasteur's fermentation studies of alcoholic beverages1 though not at the hands of ,pasteur himself4 ,struck by the boundless implications of ,pasteur's revelations regarding the bacteria1 ,dr4 ,joseph ,lister 7the present ,lord ,lister71 then of ,glasgow1 set about as early as #ahfj to make a wonderful application of these ideas4 ,if putrefaction is always due to bacterial development1 he argued1 this must apply as well to living as to dead tissues2 hence the putrefactive changes which occur in wounds and after operations on the human subject1 from which blood-poisoning so often follows1 might be absolutely prevented if the injured surfaces could be kept free from access of the germs of decay4 ,in the hope of accomplishing this result1 ,lister began experimenting with drugs that might kill the bacteria without injury to the patient1 and with means to prevent further access of germs once a wound was freed from them4 ,how well he succeeded all the world knows2 how bitterly he was antagonized for about a score of years1 most of the world has already forgotten4 ,as early as #ahfg ,lister was able to publish results pointing towards success in his great project2 yet so incredulous were surgeons in general that even some years later the leading surgeons on the ,continent had not so much as heard of his efforts4 ,in #ahgj the soldiers of ,paris died1 as of old1 of hospital gangrene2 and when1 in #ahga1 the ,french surgeon ,alphonse ,guerin1 stimulated by ,pasteur's studies1 conceived the idea of dressing wounds with cotton in the hope of keeping germs from entering them1 he was quite unaware that a ,british contemporary had preceded him by a full decade in this effort at prevention and had made long strides towards complete success4 ,lister's priority1 however1 and the superiority of his method1 were freely admitted by the ,french ,academy of ,sciences1 which in #ahha officially crowned his achievement1 as the ,royal ,society of ,london had done the year before4 ,by this time1 to be sure1 as everybody knows1 ,lister's new methods had made their way everywhere1 revolutionizing the practice of surgery and practically banishing from the earth maladies that hitherto had been the terror of the surgeon and the opprobrium of his art4 ,and these bedside studies1 conducted in the end by thousands of men who had no knowledge of microscopy1 had a large share in establishing the general belief in the causal relation that micro-organisms bear to disease1 which by about the year #ahhj had taken possession of the medical world4 ,but they did more2 they brought into equal prominence the idea that1 the cause of a diseased condition being known1 it maybe possible as never before to grapple with and eradicate that condition4 ,,preventive ,,inoculation ,the controversy over spontaneous generation1 which1 thanks to ,pasteur and ,tyndall1 had just been brought to a termination1 made it clear that no bacterium need be feared where an antecedent bacterium had not found lodgment2 ,listerism in surgery had now shown how much might be accomplished towards preventing the access of germs to abraded surfaces of the body and destroying those that already had found lodgment there4 ,as yet1 however1 there was no inkling of a way in which a corresponding onslaught might be made upon those other germs which find their way into the animal organism by way of the mouth and the nostrils1 and which1 as was now clear1 are the cause of those contagious diseases which1 first and last1 claim so large a proportion of mankind for their victims4 ,how such means might be found now became the anxious thought of every imaginative physician1 of every working microbiologist4 ,as it happened1 the world was not kept long in suspense4 ,almost before the proposition had taken shape in the minds of the other leaders1 ,pasteur had found a solution4 ,guided by the empirical success of ,jenner1 he1 like many others1 had long practised inoculation experiments1 and on ,february #i1 #ahhj1 he announced to the ,french ,academy of ,sciences that he had found a method of so reducing the virulence of a disease germ that when introduced into the system of a susceptible animal it produced only a mild form of the disease1 which1 however1 sufficed to protect against the usual virulent form exactly as vaccinia protects against small-pox4 ,the particular disease experimented with was that infectious malady of poultry known familiarly as chicken cholera4 ,in ,october of the same year ,pasteur announced the method by which this attenuation of the virus1 as he termed it1 had been brought about--by cultivation of the disease germs in artificial media1 exposed to the air1 and he did not hesitate to assert his belief that the method would prove susceptible of generalization--that is to say1 of application to other diseases than the particular one in question4 ,within a few months he made good this prophecy1 for in ,february1 #ahha1 he announced to the ,academy that with the aid1 as before1 of his associates ,,mm4 ,chamberland and ,roux1 he had produced an attenuated virus of the anthrax microbe by the use of which1 as he affirmed with great confidence1 he could protect sheep1 and presumably cattle1 against that fatal malady4 ,in some recent publications1 said ,pasteur1 ,i announced the first case of the attenuation of a virus by experimental methods only4 ,formed of a special microbe of an extreme minuteness1 this virus may be multiplied by artificial culture outside the animal body4 ,these cultures1 left alone without any possible external contamination1 undergo1 in the course of time1 modifications of their virulency to a greater or less extent4 ,the oxygen of the atmosphere is said to be the chief cause of these attenuations--that is1 this lessening of the facilities of multiplication of the microbe2 for it is evident that the difference of virulence is in some way associated with differences of development in the parasitic economy4 ,there is no need to insist upon the interesting character of these results and the deductions to be made therefrom4 ,to seek to lessen the virulence by rational means would be to establish1 upon an experimental basis1 the hope of preparing from an active virus1 easily cultivated either in the human or animal body1 a vaccine-virus of restrained development capable of preventing the fatal effects of the former4 ,therefore1 we have applied all our energies to investigate the possible generalizing action of atmospheric oxygen in the attenuation of virus4 ,the anthrax virus1 being one that has been most carefully studied1 seemed to be the first that should attract our attention4 ,every time1 however1 we encountered a difficulty4 ,between the microbe of chicken cholera and the microbe of anthrax there exists an essential difference which does not allow the new experiment to be verified by the old4 ,the microbes of chicken cholera do not1 in effect1 seem to resolve themselves1 in their culture1 into veritable germs4 ,the latter are merely cells1 or articulations always ready to multiply by division1 except when the particular conditions in which they become true germs are known4 ,the yeast of beer is a striking example of these cellular productions1 being able to multiply themselves indefinitely without the apparition of their original spores4 ,there exist many mucedines 7,mucedinae87 of tubular mushrooms1 which in certain conditions of culture produce a chain of more or less spherical cells called ,conidae4 ,the latter1 detached from their branches1 are able to reproduce themselves in the form of cells1 without the appearance1 at least with a change in the conditions of culture1 of the spores of their respective mucedines4 ,these vegetable organisms can be compared to plants which are cultivated by slipping1 and to produce which it is not necessary to have the fruits or the seeds of the mother plant4 ,the anthrax bacterium1 in its artificial cultivation1 behaves very differently4 ,its mycelian filaments1 if one may so describe them1 have been produced scarcely for twenty-four or forty-eight hours when they are seen to transform themselves1 those especially which are in free contact with the air1 into very refringent corpuscles1 capable of gradually isolating themselves into true germs of slight organization4 ,moreover1 observation shows that these germs1 formed so quickly in the culture1 do not undergo1 after exposure for a time to atmospheric air1 any change either in their vitality or their virulence4 ,i was able to present to the ,academy a tube containing some spores of anthrax bacteria produced four years ago1 on ,march #ba1 #ahhg4 ,each year the germination of these little corpuscles has been tried1 and each year the germination has been accomplished with the same facility and the same rapidity as at first4 ,each year also the virulence of the new cultures has been tested1 and they have not shown any visible falling off4 ,therefore1 how can we experiment with the action of the air upon the anthrax virus with any expectation of making it less virulent8 ,the crucial difficulty lies perhaps entirely in this rapid reproduction of the bacteria germs which we have just related4 ,in its form of a filament1 and in its multiplication by division1 is not this organism at all points comparable with the microbe of the chicken cholera8 ,that a germ1 properly so called1 that a seed1 does not suffer any modification on account of the air is easily conceived2 but it is conceivable not less easily that if there should be any change it would occur by preference in the case of a mycelian fragment4 ,it is thus that a slip which may have been abandoned in the soil in contact with the air does not take long to lose all vitality1 while under similar conditions a seed is preserved in readiness to reproduce the plant4 ,if these views have any foundation1 we are led to think that in order to prove the action of the air upon the anthrax bacteria it will be indispensable to submit to this action the mycelian development of the minute organism under conditions where there cannot be the least admixture of corpuscular germs4 ,hence the problem of submitting the bacteria to the action of oxygen comes back to the question of presenting entirely the formation of spores4 ,the question being put in this way1 we are beginning to recognize that it is capable of being solved4 ,we can1 in fact1 prevent the appearance of spores in the artificial cultures of the anthrax parasite by various artifices4 ,at the lowest temperature at which this parasite can be cultivated--that is to say1 about #af degrees ,centigrade--the bacterium does not produce germs--at any rate1 for a very long time4 ,the shapes of the minute microbe at this lowest limit of its development are irregular1 in the form of balls and pears--in a word1 they are monstrosities--but they are without spores4 ,in the last regard also it is the same at the highest temperatures at which the parasite can be cultivated1 temperatures which vary slightly according to the means employed4 ,in neutral chicken bouillon the bacteria cannot be cultivated above #de degrees4 ,culture1 however1 is easy and abundant at #db to #dc degrees1 but equally without any formation of spores4 ,consequently a culture of mycelian bacteria can be kept entirely free from germs while in contact with the open air at a temperature of from #db to #dc degrees ,centigrade4 ,now appear the three remarkable results4 ,after about one month of waiting the culture dies--that is to say1 if put into a fresh bouillon it becomes absolutely sterile4 ,so much for the life and nutrition of this organism4 ,in respect to its virulence1 it is an extraordinary fact that it disappears entirely after eight days' culture at #db to #dc degrees ,centigrade1 or1 at any rate1 the cultures are innocuous for the guinea-pig1 the rabbit1 and the sheep1 the three kinds of animals most apt to contract anthrax4 ,we are thus able to obtain1 not only the attenuation of the virulence1 but also its complete suppression by a simple method of cultivation4 ,moreover1 we see also the possibility of preserving and cultivating the terrible microbe in an inoffensive state4 ,what is it that happens in these eight days at #dc degrees that suffices to take away the virulence of the bacteria8 ,let us remember that the microbe of chicken cholera dies in contact with the air1 in a period somewhat protracted1 it is true1 but after successive attenuations4 ,are we justified in thinking that it ought to be the same in regard to the microbe of anthrax8 ,this hypothesis is confirmed by experiment4 ,before the disappearance of its virulence the anthrax microbe passes through various degrees of attenuation1 and1 moreover1 as is also the case with the microbe of chicken cholera1 each of these attenuated states of virulence can be obtained by cultivation4 ,moreover1 since1 according to one of our recent ,communications1 anthrax is not recurrent1 each of our attenuated anthrax microbes is1 for the better-developed microbe1 a vaccine--that is to say1 a virus producing a less-malignant malady4 ,what1 therefore1 is easier than to find in these a virus that will infect with anthrax sheep1 cows1 and horses1 without killing them1 and ultimately capable of warding off the mortal malady8 ,we have practised this experiment with great success upon sheep1 and when the season comes for the assembling of the flocks at ,beauce we shall try the experiment on a larger scale4 ,already ,m4 ,toussaint has announced that sheep can be saved by preventive inoculations2 but when this able observer shall have published his results2 on the subject of which we have made such exhaustive studies1 as yet unpublished1 we shall be able to see the whole difference which exists between the two methods--the uncertainty of the one and the certainty of the other4 ,that which we announce has1 moreover1 the very great advantage of resting upon the existence of a poison vaccine cultivable at will1 and which can be increased indefinitely in the space of a few hours without having recourse to infected blood47#h7 ,this announcement was immediately challenged in a way that brought it to the attention of the entire world4 ,the president of an agricultural society1 realizing the enormous importance of the subject1 proposed to ,pasteur that his alleged discovery should be submitted to a decisive public test4 ,he proposed to furnish a drove of fifty sheep half of which were to be inoculated with the attenuated virus of ,pasteur4 ,subsequently all the sheep were to be inoculated with virulent virus1 all being kept together in one pen under precisely the same conditions4 ,the protected sheep were to remain healthy2 the unprotected ones to die of anthrax2 so read the terms of the proposition4 ,pasteur accepted the challenge2 he even permitted a change in the programme by which two goats were substituted for two of the sheep1 and ten cattle added1 stipulating1 however1 that since his experiments had not yet been extended to cattle these should not be regarded as falling rigidly within the terms of the test4 ,it was a test to try the soul of any man1 for all the world looked on askance1 prepared to deride the maker of so preposterous a claim as soon as his claim should be proved baseless4 ,not even the fame of ,pasteur could make the public at large1 lay or scientific1 believe in the possibility of what he proposed to accomplish4 ,there was time for all the world to be informed of the procedure1 for the first preventive inoculation--or vaccination1 as ,pasteur termed it--was made on ,may #eth1 the second on ,may #agth1 and another interval of two weeks must elapse before the final inoculations with the unattenuated virus4 ,twenty-four sheep1 one goat1 and five cattle were submitted to the preliminary vaccinations4 ,then1 on ,may #ca st1 all sixty of the animals were inoculated1 a protected and unprotected one alternately1 with an extremely virulent culture of anthrax microbes that had been in ,pasteur's laboratory since #ahgg4 ,this accomplished1 the animals were left together in one enclosure to await the issue4 ,two days later1 ,june #b;d1 at the appointed hour of rendezvous1 a vast crowd1 composed of veterinary surgeons1 newspaper correspondents1 and farmers from far and near1 gathered to witness the closing scenes of this scientific tourney4 ,what they saw was one of the most dramatic scenes in the history of peaceful science--a scene which1 as ,pasteur declared afterwards1 amazed the assembly4 ,scattered about the enclosure1 dead1 dying1 or manifestly sick unto death1 lay the unprotected animals1 one and all1 while each and every protected animal stalked unconcernedly about with every appearance of perfect health4 ,twenty of the sheep and the one goat were already dead2 two other sheep expired under the eyes of the spectators2 the remaining victims lingered but a few hours longer4 ,thus in a manner theatrical enough1 not to say tragic1 was proclaimed the unequivocal victory of science4 ,naturally enough1 the unbelievers struck their colors and surrendered without terms2 the principle of protective vaccination1 with a virus experimentally prepared in the laboratory1 was established beyond the reach of controversy4 ,that memorable scientific battle marked the beginning of a new era in medicine4 ,it was a foregone conclusion that the principle thus established would be still further generalized2 that it would be applied to human maladies2 that in all probability it would grapple successfully1 sooner or later1 with many infectious diseases4 ,that expectation has advanced rapidly towards realization4 ,pasteur himself made the application to the human subject in the disease hydrophobia in #ahhe1 since which time that hitherto most fatal of maladies has largely lost its terrors4 ,thousands of persons bitten by mad dogs have been snatched from the fatal consequences of that mishap by this method at the ,pasteur ,institute in ,paris1 and at the similar institutes1 built on the model of this parent one1 that have been established all over the world in regions as widely separated as ,new ,york and ,nha-,trang4 ,,serum-,,therapy ,in the production of the rabies vaccine ,pasteur and his associates developed a method of attenuation of a virus quite different from that which had been employed in the case of the vaccines of chicken cholera and of anthrax4 ,the rabies virus was inoculated into the system of guinea-pigs or rabbits and1 in effect1 cultivated in the systems of these animals4 ,the spinal cord of these infected animals was found to be rich in the virus1 which rapidly became attenuated when the cord was dried in the air4 ,the preventive virus1 of varying strengths1 was made by maceration of these cords at varying stages of desiccation4 ,this cultivation of a virus within the animal organism suggested1 no doubt1 by the familiar ,jennerian method of securing small-pox vaccine1 was at the same time a step in the direction of a new therapeutic procedure which was destined presently to become of all-absorbing importance--the method1 namely1 of so-called serum-therapy1 or the treatment of a disease with the blood serum of an animal that has been subjected to protective inoculation against that disease4 ,the possibility of such a method was suggested by the familiar observation1 made by ,pasteur and numerous other workers1 that animals of different species differ widely in their susceptibility to various maladies1 and that the virus of a given disease may become more and more virulent when passed through the systems of successive individuals of one species1 and1 contrariwise1 less and less virulent when passed through the systems of successive individuals of another species4 ,these facts suggested the theory that the blood of resistant animals might contain something directly antagonistic to the virus1 and the hope that this something might be transferred with curative effect to the blood of an infected susceptible animal4 ,numerous experimenters all over the world made investigations along the line of this alluring possibility1 the leaders perhaps being ,drs4 ,behring and ,kitasato1 closely followed by ,dr4 ,roux and his associates of the ,pasteur ,institute of ,paris4 ,definite results were announced by ,behring in #ahib regarding two important diseases--tetanus and diphtheria--but the method did not come into general notice until #ahid1 when ,dr4 ,roux read an epoch-making paper on the subject at the ,congress of ,hygiene at ,buda-,pesth4 ,in this paper ,dr4 ,roux1 after adverting to the labors of ,behring1 ,ehrlich1 ,boer1 ,kossel1 and ,wasserman1 described in detail the methods that had been developed at the ,pasteur ,institute for the development of the curative serum1 to which ,behring had given the since-familiar name antitoxine4 ,the method consists1 first1 of the cultivation1 for some months1 of the diphtheria bacillus 7called the ,klebs-,loeffler bacillus1 in honor of its discoverers7 in an artificial bouillon1 for the development of a powerful toxine capable of giving the disease in a virulent form4 ,this toxine1 after certain details of mechanical treatment1 is injected in small but increasing doses into the system of an animal1 care being taken to graduate the amount so that the animal does not succumb to the disease4 ,after a certain course of this treatment it is found that a portion of blood serum of the animal so treated will act in a curative way if injected into the blood of another animal1 or a human patient1 suffering with diphtheria4 ,in other words1 according to theory1 an antitoxine has been developed in the system of the animal subjected to the progressive inoculations of the diphtheria toxine4 ,in ,dr4 ,roux's experience the animal best suited for the purpose is the horse1 though almost any of the domesticated animals will serve the purpose4 ,but ,dr4 ,roux's paper did not stop with the description of laboratory methods4 ,it told also of the practical application of the serum to the treatment of numerous cases of diphtheria in the hospitals of ,paris--applications that had met with a gratifying measure of success4 ,he made it clear that a means had been found of coping successfully with what had been one of the most virulent and intractable of the diseases of childhood4 ,hence it was not strange that his paper made a sensation in all circles1 medical and lay alike4 ,physicians from all over the world flocked to ,paris to learn the details of the open secret1 and within a few months the new serum-therapy had an acknowledged standing with the medical profession everywhere4 ,what it had accomplished was regarded as but an earnest of what the new method might accomplish presently when applied to the other infectious diseases4 ,efforts at such applications were immediately begun in numberless directions--had1 indeed1 been under way in many a laboratory for some years before4 ,it is too early yet to speak of the results in detail4 ,but enough has been done to show that this method also is susceptible of the widest generalization4 ,it is not easy at the present stage to sift that which is tentative from that which will be permanent2 but so great an authority as ,behring does not hesitate to affirm that today we possess1 in addition to the diphtheria antitoxine1 equally specific antitoxines of tetanus1 cholera1 typhus fever1 pneumonia1 and tuberculosis--a set of diseases which in the aggregate account for a startling proportion of the general death-rate4 ,then it is known that ,dr4 ,yersin1 with the collaboration of his former colleagues of the ,pasteur ,institute1 has developed1 and has used with success1 an antitoxine from the microbe of the plague which recently ravaged ,china4 ,dr4 ,calmette1 another graduate of the ,pasteur ,institute1 has extended the range of the serum-therapy to include the prevention and treatment of poisoning by venoms1 and has developed an antitoxine that has already given immunity from the lethal effects of snake bites to thousands of persons in ,india and ,australia4 ,just how much of present promise is tentative1 just what are the limits of the methods--these are questions for the future to decide4 ,but1 in any event1 there seems little question that the serum treatment will stand as the culminating achievement in therapeutics of our century4 ,it is the logical outgrowth of those experimental studies with the microscope begun by our predecessors of the thirties1 and it represents the present culmination of the rigidly experimental method which has brought medicine from a level of fanciful empiricism to the plane of a rational experimental science4 ,,ix4 ,,the ,,new ,,science ,,of ,,experimental ,,psychology ,,brain ,,and ,,mind ,a little over a hundred years ago a reform movement was afoot in the world in the interests of the insane4 ,as was fitting1 the movement showed itself first in ,america1 where these unfortunates were humanely cared for at a time when their treatment elsewhere was worse than brutal2 but ,england and ,france quickly fell into line4 ,the leader on this side of the water was the famous ,philadelphian1 ,dr4 ,benjamin ,rush1 the ,sydenham of ,america2 in ,england1 ,dr4 ,william ,tuke inaugurated the movement2 and in ,france1 ,dr4 ,philippe ,pinel1 single-handed1 led the way4 ,moved by a common spirit1 though acting quite independently1 these men raised a revolt against the traditional custom which1 spurning the insane as demon-haunted outcasts1 had condemned these unfortunates to dungeons1 chains1 and the lash4 ,hitherto few people had thought it other than the natural course of events that the maniac should be thrust into a dungeon1 and perhaps chained to the wall with the aid of an iron band riveted permanently about his neck or waist4 ,many an unfortunate1 thus manacled1 was held to the narrow limits of his chain for years together in a cell to which full daylight never penetrated2 sometimes--iron being expensive--the chain was so short that the wretched victim could not rise to the upright posture or even shift his position upon his squalid pallet of straw4 ,in ,america1 indeed1 there being no ,middle ,age precedents to crystallize into established customs1 the treatment accorded the insane had seldom or never sunk to this level4 ,partly for this reason1 perhaps1 the work of ,dr4 ,rush at the ,philadelphia ,hospital1 in #aghd1 by means of which the insane came to be humanely treated1 even to the extent of banishing the lash1 has been but little noted1 while the work of the ,european leaders1 though belonging to later decades1 has been made famous4 ,and perhaps this is not as unjust as it seems1 for the step which ,rush took1 from relatively bad to good1 was a far easier one to take than the leap from atrocities to good treatment which the ,european reformers were obliged to compass4 ,in ,paris1 for example1 ,pinel was obliged to ask permission of the authorities even to make the attempt at liberating the insane from their chains1 and1 notwithstanding his recognized position as a leader of science1 he gained but grudging assent1 and was regarded as being himself little better than a lunatic for making so manifestly unwise and hopeless an attempt4 ,once the attempt had been made1 however1 and carried to a successful issue1 the amelioration wrought in the condition of the insane was so patent that the fame of ,pinel's work at the ,bicetre and the ,salpetriere went abroad apace4 ,it required1 indeed1 many years to complete it in ,paris1 and a lifetime of effort on the part of ,pinel's pupil ,esquirol and others to extend the reform to the provinces2 but the epochal turning-point had been reached with ,pinel's labors of the closing years of the eighteenth century4 ,the significance of this wise and humane reform1 in the present connection1 is the fact that these studies of the insane gave emphasis to the novel idea1 which by-and-by became accepted as beyond question1 that demoniacal possession is in reality no more than the outward expression of a diseased condition of the brain4 ,this realization made it clear1 as never before1 how intimately the mind and the body are linked one to the other4 ,and so it chanced that1 in striking the shackles from the insane1 ,pinel and his confreres struck a blow also1 unwittingly1 at time-honored philosophical traditions4 ,the liberation of the insane from their dungeons was an augury of the liberation of psychology from the musty recesses of metaphysics4 ,hitherto psychology1 in so far as it existed at all1 was but the subjective study of individual minds2 in future it must become objective as well1 taking into account also the relations which the mind bears to the body1 and in particular to the brain and nervous system4 ,the necessity for this collocation was advocated quite as earnestly1 and even more directly1 by another worker of this period1 whose studies were allied to those of alienists1 and who1 even more actively than they1 focalized his attention upon the brain and its functions4 ,this earliest of specialists in brain studies was a ,german by birth but ,parisian by adoption1 ,dr4 ,franz ,joseph ,gall1 originator of the since-notorious system of phrenology4 ,the merited disrepute into which this system has fallen through the exposition of peripatetic charlatans should not make us forget that ,dr4 ,gall himself was apparently a highly educated physician1 a careful student of the brain and mind according to the best light of his time1 and1 withal1 an earnest and honest believer in the validity of the system he had originated4 ,the system itself1 taken as a whole1 was hopelessly faulty1 yet it was not without its latent germ of truth1 as later studies were to show4 ,how firmly its author himself believed in it is evidenced by the paper which he contributed to the ,french ,academy of ,sciences in #ahjh4 ,the paper itself was referred to a committee of which ,pinel and ,cuvier were members4 ,the verdict of this committee was adverse1 and justly so2 yet the system condemned had at least one merit which its detractors failed to realize4 ,it popularized the conception that the brain is the organ of mind4 ,moreover1 by its insistence it rallied about it a band of scientific supporters1 chief of whom was ,dr4 ,kaspar ,spurzlieim1 a man of no mean abilities1 who became the propagandist of phrenology in ,england and in ,america4 ,of course such advocacy and popularity stimulated opposition as well1 and out of the disputations thus arising there grew presently a general interest in the brain as the organ of mind1 quite aside from any preconceptions whatever as to the doctrines of ,gall and ,spurzheim4 ,prominent among the unprejudiced class of workers who now appeared was the brilliant young ,frenchman ,louis ,antoine ,desmoulins1 who studied first under the tutorage of the famous ,magendie1 and published jointly with him a classical work on the nervous system of vertebrates in #ahbe4 ,desmoulins made at least one discovery of epochal importance4 ,he observed that the brains of persons dying in old age were lighter than the average and gave visible evidence of atrophy1 and he reasoned that such decay is a normal accompaniment of senility4 ,no one nowadays would question the accuracy of this observation1 but the scientific world was not quite ready for it in #ahbe2 for when ,desmoulins announced his discovery to the ,french ,academy1 that august and somewhat patriarchal body was moved to quite unscientific wrath1 and forbade the young iconoclast the privilege of further hearings4 ,from which it is evident that the partially liberated spirit of the new psychology had by no means freed itself altogether1 at the close of the first quarter of the nineteenth century1 from the metaphysical cobwebs of its long incarceration4 ,,functions ,,of ,,the ,,nerves ,while studies of the brain were thus being inaugurated1 the nervous system1 which is the channel of communication between the brain and the outside world1 was being interrogated with even more tangible results4 ,the inaugural discovery was made in #ahaa by ,dr4 7afterwards ,sir ,charles7 ,bell17#a7 the famous ,english surgeon and experimental physiologist4 ,it consisted of the observation that the anterior roots of the spinal nerves are given over to the function of conveying motor impulses from the brain outward1 whereas the posterior roots convey solely sensory impulses to the brain from without4 ,hitherto it had been supposed that all nerves have a similar function1 and the peculiar distribution of the spinal nerves had been an unsolved puzzle4 ,bell's discovery was epochal2 but its full significance was not appreciated for a decade1 nor1 indeed1 was its validity at first admitted4 ,in ,paris1 in particular1 then the court of final appeal in all matters scientific1 the alleged discovery was looked at askance1 or quite ignored4 ,but in #ahbc the subject was taken up by the recognized leader of ,french physiology--,francois ,magendie--in the course of his comprehensive experimental studies of the nervous system1 and ,bell's conclusions were subjected to the most rigid experimental tests and found altogether valid4 ,bell himself1 meanwhile1 had turned his attention to the cranial nerves1 and had proved that these also are divisible into two sets--sensory and motor4 ,sometimes1 indeed1 the two sets of filaments are combined into one nerve cord1 but if traced to their origin these are found to arise from different brain centres4 ,thus it was clear that a hitherto unrecognized duality of function pertains to the entire extra-cranial nervous system4 ,any impulse sent from the periphery to the brain must be conveyed along a perfectly definite channel2 the response from the brain1 sent out to the peripheral muscles1 must traverse an equally definite and altogether different course4 ,if either channel is interrupted--as by the section of its particular nerve tract--the corresponding message is denied transmission as effectually as an electric current is stopped by the section of the transmitting wire4 ,experimenters everywhere soon confirmed the observations of ,bell and ,magendie1 and1 as always happens after a great discovery1 a fresh impulse was given to investigations in allied fields4 ,nevertheless1 a full decade elapsed before another discovery of comparable importance was made4 ,then ,marshall ,hall1 the most famous of ,english physicians of his day1 made his classical observations on the phenomena that henceforth were to be known as reflex action4 ,in #ahcb1 while experimenting one day with a decapitated newt1 he observed that the headless creature's limbs would contract in direct response to certain stimuli4 ,such a response could no longer be secured if the spinal nerves supplying a part were severed4 ,hence it was clear that responsive centres exist in the spinal cord capable of receiving a sensory message and of transmitting a motor impulse in reply--a function hitherto supposed to be reserved for the brain4 ,further studies went to show that such phenomena of reflex action on the part of centres lying outside the range of consciousness1 both in the spinal cord and in the brain itself1 are extremely common2 that1 in short1 they enter constantly into the activities of every living organism and have a most important share in the sum total of vital movements4 ,hence1 ,hall's discovery must always stand as one of the great mile-stones of the advance of neurological science4 ,hall gave an admirably clear and interesting account of his experiments and conclusions in a paper before the ,royal ,society1 ,on the ,reflex ,functions of the ,medulla ,oblongata and the ,medulla ,spinalis1 from which1 as published in the ,transactions of the society for #ahcc1 we may quote at some length3 ,in the entire animal1 sensation and voluntary motion1 functions of the cerebrum1 combine with the functions of the medulla oblongata and medulla spinalis1 and may therefore render it difficult or impossible to determine those which are peculiar to each2 if1 in an animal deprived of the brain1 the spinal marrow or the nerves supplying the muscles be stimulated1 those muscles1 whether voluntary or respiratory1 are equally thrown into contraction1 and1 it may be added1 equally in the complete and in the mutilated animal2 and1 in the case of the nerves1 equally in limbs connected with and detached from the spinal marrow4 ,the operation of all these various causes may be designated centric1 as taking place ,,at1 or at least in a direction ,,from1 central parts of the nervous system4 ,but there is another function the phenomena of which are of a totally different order and obey totally different laws1 being excited by causes in a situation which is ,,excentric in the nervous system--that is1 distant from the nervous centres4 ,this mode of action has not1 ,i think1 been hitherto distinctly understood by physiologists4 ,many of the phenomena of this principle of action1 as they occur in the limbs1 have certainly been observed4 ,but1 in the first place1 this function is by no means confined to the limbs2 for1 while it imparts to each muscle its appropriate tone1 and to each system of muscles its appropriate equilibrium or balance1 it performs the still more important office of presiding over the orifices and terminations of each of the internal canals in the animal economy1 giving them their due form and action2 and1 in the second place1 in the instances in which the phenomena of this function have been noticed1 they have been confounded1 as ,i have stated1 with those of sensation and volition2 or1 if they have been distinguished from these1 they have been too indefinitely denominated instinctive1 or automatic4 ,i have been compelled1 therefore1 to adopt some new designation for them1 and ,i shall now give the reasons for my choice of that which is given in the title of this paper--',reflex ,functions4' ,this property is characterized by being ,,excited in its action and ,,reflex in its course3 in every instance in which it is exerted an impression made upon the extremities of certain nerves is conveyed to the medulla oblongata or the medulla spinalis1 and is reflected along the nerves to parts adjacent to1 or remote from1 that which has received the impression4 ,it is by this reflex character that the function to which ,i have alluded is to be distinguished from every other4 ,there are1 in the animal economy1 four modes of muscular action1 of muscular contraction4 ,the first is that designated ,,voluntary3 volition1 originated in the cerebrum and spontaneous in its acts1 extends its influence along the spinal marrow and the motor nerves in a ,,direct ,,line to the voluntary muscles4 ,the ,,second is that of ,,respiration3 like volition1 the motive influence in respiration passes in a ,,direct ,,line from one point of the nervous system to certain muscles2 but as voluntary motion seems to originate in the cerebrum1 so the respiratory motions originate in the medulla oblongata3 like the voluntary motions1 the motions of respirations are spontaneous2 they continue1 at least1 after the eighth pair of nerves have been divided4 ,the ,,third kind of muscular action in the animal economy is that termed involuntary3 it depends upon the principle of irritability and requires the ,,immediate application of a stimulus to the nervo-muscular fibre itself4 ,these three kinds of muscular motion are well known to physiologists2 and ,i believe they are all which have been hitherto pointed out4 ,there is1 however1 a ,,fourth1 which subsists1 in part1 after the voluntary and respiratory motions have ceased1 by the removal of the cerebrum and medulla oblongata1 and which is attached to the medulla spinalis1 ceasing itself when this is removed1 and leaving the irritability undiminished4 ,in this kind of muscular motion the motive influence does not originate in any central part of the nervous system1 but from a distance from that centre2 it is neither spontaneous in its action nor direct in its course2 it is1 on the contrary1 ,,excited by the application of appropriate stimuli1 which are not1 however1 applied immediately to the muscular or nervo-muscular fibre1 but to certain membraneous parts1 whence the impression is carried through the medulla1 ,,reflected and reconducted to the part impressed1 or conducted to a part remote from it in which muscular contraction is effected4 ,the first three modes of muscular action are known only by actual movements of muscular contractions4 ,but the reflex function exists as a continuous muscular action1 as a power presiding over organs not actually in a state of motion1 preserving in some1 as the glottis1 an open1 in others1 as the sphincters1 a closed form1 and in the limbs a due degree of equilibrium or balanced muscular action--a function not1 ,i think1 hitherto recognized by physiologists4 ,the three kinds of muscular motion hitherto known may be distinguished in another way4 ,the muscles of voluntary motion and of respiration may be excited by stimulating the nerves which supply them1 in any part of their course1 whether at their source as a part of the medulla oblongata or the medulla spinalis or exterior to the spinal canal3 the muscles of involuntary motion are chiefly excited by the actual contact of stimuli4 ,in the case of the reflex function alone the muscles are excited by a stimulus acting mediately and indirectly in a curved and reflex course1 along superficial subcutaneous or submucous nerves proceeding from the medulla4 ,the first three of these causes of muscular motion may act on detached limbs or muscles4 ,the last requires the connection with the medulla to be preserved entire4 ,all the kinds of muscular motion may be unduly excited1 but the reflex function is peculiar in being excitable in two modes of action1 not previously subsisting in the animal economy1 as in the case of sneezing1 coughing1 vomiting1 etc4 ,the reflex function also admits of being permanently diminished or augmented and of taking on some other morbid forms1 of which ,i shall treat hereafter4 ,before ,i proceed to the details of the experiments upon which this disposition rests1 it may be well to point out several instances in illustration of the various sources of and the modes of muscular action which have been enumerated4 ,none can be more familiar than the act of swallowing4 ,yet how complicated is the act6 ,the apprehension of the food by the teeth and tongue1 etc41 is voluntary1 and cannot1 therefore1 take place in an animal from which the cerebrum is removed4 ,the transition of food over the glottis and along the middle and lower part of the pharynx depends upon the reflex action3 it can take place in animals from which the cerebrum has been removed or the ninth pair of nerves divided2 but it requires the connection with the medulla oblongata to be preserved entirely2 and the actual contact of some substance which may act as a stimulus3 it is attended by the accurate closure of the glottis and by the contraction of the pharynx4 ,the completion of the act of deglutition is dependent upon the stimulus immediately impressed upon the muscular fibre of the oesophagus1 and is the result of excited irritability4 ,however plain these observations may have made the fact that there is a function of the nervous muscular system distinct from sensation1 from the voluntary and respiratory motions1 and from irritability1 it is right1 in every such inquiry as the present1 that the statements and reasonings should be made with the experiment1 as it were1 actually before us4 ,it has already been remarked that the voluntary and respiratory motions are spontaneous1 not necessarily requiring the agency of a stimulus4 ,if1 then1 an animal can be placed in such circumstances that such motions will certainly not take place1 the power of moving remaining1 it may be concluded that volition and the motive influence of respiration are annihilated4 ,now this is effected by removing the cerebrum and the medulla oblongata4 ,these facts are fully proved by the experiments of ,legallois and ,m4 ,flourens1 and by several which ,i proceed to detail1 for the sake of the opportunity afforded by doing so of stating the arguments most clearly4 ,i divided the spinal marrow of a very lively snake between the second and third vertebrae4 ,the movements of the animal were immediately before extremely vigorous and unintermitted4 ,from the moment of the division of the spinal marrow it lay perfectly tranquil and motionless1 with the exception of occasional gaspings and slight movements of the head4 ,it became quite evident that this state of quiescence would continue indefinitely were the animal secured from all external impressions4 ,being now stimulated1 the body began to move with great activity1 and continued to do so for a considerable time1 each change of position or situation bringing some fresh part of the surface of the animal into contact with the table or other objects and renewing the application of stimulants4 ,at length the animal became again quiescent2 and being carefully protected from all external impressions it moved no more1 but died in the precise position and form which it had last assumed4 ,it requires a little manoeuvre to perform this experiment successfully3 the motions of the animal must be watched and slowly and cautiously arrested by opposing some soft substance1 as a glove or cotton wool2 they are by this means gradually lulled into quiescence4 ,the slightest touch with a hard substance1 the slightest stimulus1 will1 on the other hand1 renew the movements on the animal in an active form4 ,but that this phenomenon does not depend upon sensation is further fully proved by the facts that the position last assumed1 and the stimuli1 may be such as would be attended by extreme or continued pain1 if the sensibility were undestroyed3 in one case the animal remained partially suspended over the acute edge of the table2 in others the infliction of punctures and the application of a lighted taper did not prevent the animal1 still possessed of active powers of motion1 from passing into a state of complete and permanent quiescence4 ,in summing up this long paper ,hall concludes with this sentence3 ,the reflex function appears in a word to be the ,,complement of the functions of the nervous system hitherto known47#b7 ,all these considerations as to nerve currents and nerve tracts becoming stock knowledge of science1 it was natural that interest should become stimulated as to the exact character of these nerve tracts in themselves1 and all the more natural in that the perfected microscope was just now claiming all fields for its own4 ,a troop of observers soon entered upon the study of the nerves1 and the leader here1 as in so many other lines of microscopical research1 was no other than ,theodor ,schwann4 ,through his efforts1 and with the invaluable aid of such other workers as ,remak1 ,purkinje1 ,henle1 ,muller1 and the rest1 all the mystery as to the general characteristics of nerve tracts was cleared away4 ,it came to be known that in its essentials a nerve tract is a tenuous fibre or thread of protoplasm stretching between two terminal points in the organism1 one of such termini being usually a cell of the brain or spinal cord1 the other a distribution-point at or near the periphery--for example1 in a muscle or in the skin4 ,such a fibril may have about it a protective covering1 which is known as the sheath of ,schwann2 but the fibril itself is the essential nerve tract2 and in many cases1 as ,remak presently discovered1 the sheath is dispensed with1 particularly in case of the nerves of the so-called sympathetic system4 ,this sympathetic system of ganglia and nerves1 by-the-bye1 had long been a puzzle to the physiologists4 ,its ganglia1 the seeming centre of the system1 usually minute in size and never very large1 are found everywhere through the organism1 but in particular are gathered into a long double chain which lies within the body cavity1 outside the spinal column1 and represents the sole nervous system of the non-vertebrated organisms4 ,fibrils from these ganglia were seen to join the cranial and spinal nerve fibrils and to accompany them everywhere1 but what special function they subserved was long a mere matter of conjecture and led to many absurd speculations4 ,fact was not substituted for conjecture until about the year #ahea1 when the great ,frenchman ,claude ,bernard conclusively proved that at least one chief function of the sympathetic fibrils is to cause contraction of the walls of the arterioles of the system1 thus regulating the blood-supply of any given part4 ,ten years earlier ,henle had demonstrated the existence of annular bands of muscle fibres in the arterioles1 hitherto a much-mooted question1 and several tentative explanations of the action of these fibres had been made1 particularly by the brothers ,weber1 by ,stilling1 who1 as early as #ahdj1 had ventured to speak of vaso-motor nerves1 and by ,schiff1 who was hard upon the same track at the time of ,bernard's discovery4 ,but a clear light was not thrown on the subject until ,bernard's experiments were made in #ahea4 ,the experiments were soon after confirmed and extended by ,brown-,sequard1 ,waller1 ,budge1 and numerous others1 and henceforth physiologists felt that they understood how the blood-supply of any given part is regulated by the nervous system4 ,in reality1 however1 they had learned only half the story1 as ,bernard himself proved only a few years later by opening up a new and quite unsuspected chapter4 ,while experimenting in #aheh he discovered that there are certain nerves supplying the heart which1 if stimulated1 cause that organ to relax and cease beating4 ,as the heart is essentially nothing more than an aggregation of muscles1 this phenomenon was utterly puzzling and without precedent in the experience of physiologists4 ,an impulse travelling along a motor nerve had been supposed to be able to cause a muscular contraction and to do nothing else2 yet here such an impulse had exactly the opposite effect4 ,the only tenable explanation seemed to be that this particular impulse must arrest or inhibit the action of the impulses that ordinarily cause the heart muscles to contract4 ,but the idea of such inhibition of one impulse by another was utterly novel and at first difficult to comprehend4 ,gradually1 however1 the idea took its place in the current knowledge of nerve physiology1 and in time it came to be understood that what happens in the case of the heart nerve-supply is only a particular case under a very general1 indeed universal1 form of nervous action4 ,growing out of ,bernard's initial discovery came the final understanding that the entire nervous system is a mechanism of centres subordinate and centres superior1 the action of the one of which may be counteracted and annulled in effect by the action of the other4 ,this applies not merely to such physical processes as heart-beats and arterial contraction and relaxing1 but to the most intricate functionings which have their counterpart in psychical processes as well4 ,thus the observation of the inhibition of the heart's action by a nervous impulse furnished the point of departure for studies that led to a better understanding of the modus operandi of the mind's activities than had ever previously been attained by the most subtle of psychologists4 ,,psycho-,,physics ,the work of the nerve physiologists had thus an important bearing on questions of the mind4 ,but there was another company of workers of this period who made an even more direct assault upon the citadel of thought4 ,a remarkable school of workers had been developed in ,germany1 the leaders being men who1 having more or less of innate metaphysical bias as a national birthright1 had also the instincts of the empirical scientist1 and whose educational equipment included a profound knowledge not alone of physiology and psychology1 but of physics and mathematics as well4 ,these men undertook the novel task of interrogating the relations of body and mind from the standpoint of physics4 ,they sought to apply the vernier and the balance1 as far as might be1 to the intangible processes of mind4 ,the movement had its precursory stages in the early part of the century1 notably in the mathematical psychology of ,herbart1 but its first definite output to attract general attention came from the master-hand of ,hermann ,helmholtz in #ahea4 ,it consisted of the accurate measurement of the speed of transit of a nervous impulse along a nerve tract4 ,to make such measurement had been regarded as impossible1 it being supposed that the flight of the nervous impulse was practically instantaneous4 ,but ,helmholtz readily demonstrated the contrary1 showing that the nerve cord is a relatively sluggish message-bearer4 ,according to his experiments1 first performed upon the frog1 the nervous current travels less than one hundred feet per second4 ,other experiments performed soon afterwards by ,helmholtz himself1 and by various followers1 chief among whom was ,du ,bois-,reymond1 modified somewhat the exact figures at first obtained1 but did not change the general bearings of the early results4 ,thus the nervous impulse was shown to be something far different1 as regards speed of transit1 at any rate1 from the electric current to which it had been so often likened4 ,an electric current would flash halfway round the globe while a nervous impulse could travel the length of the human body--from a man's foot to his brain4 ,the tendency to bridge the gulf that hitherto had separated the physical from the psychical world was further evidenced in the following decade by ,helmholtz's remarkable but highly technical study of the sensations of sound and of color in connection with their physical causes1 in the course of which he revived the doctrine of color vision which that other great physiologist and physicist1 ,thomas ,young1 had advanced half a century before4 ,the same tendency was further evidenced by the appearance1 in #aheb1 of ,dr4 ,hermann ,lotze's famous ,medizinische ,psychologie1 oder ,physiologie der ,seele1 with its challenge of the old myth of a vital force4 ,but the most definite expression of the new movement was signalized in #ahfj1 when ,gustav ,fechner published his classical work called ,psychophysik4 ,that title introduced a new word into the vocabulary of science4 ,fechner explained it by saying1 ,i mean by psychophysics an exact theory of the relation between spirit and body1 and1 in a general way1 between the physical and the psychic worlds4 ,the title became famous and the brunt of many a controversy4 ,so also did another phrase which ,fechner introduced in the course of his book--the phrase physiological psychology4 ,in making that happy collocation of words ,fechner virtually christened a new science4 ,,fechner ,,expounds ,,weber',s ,,law ,the chief purport of this classical book of the ,german psycho-physiologist was the elaboration and explication of experiments based on a method introduced more than twenty years earlier by his countryman ,e4 ,h4 ,weber1 but which hitherto had failed to attract the attention it deserved4 ,the method consisted of the measurement and analysis of the definite relation existing between external stimuli of varying degrees of intensity 7various sounds1 for example7 and the mental states they induce4 ,weber's experiments grew out of the familiar observation that the nicety of our discriminations of various sounds1 weights1 or visual images depends upon the magnitude of each particular cause of a sensation in its relation with other similar causes4 ,thus1 for example1 we cannot see the stars in the daytime1 though they shine as brightly then as at night4 ,again1 we seldom notice the ticking of a clock in the daytime1 though it may become almost painfully audible in the silence of the night4 ,yet again1 the difference between an ounce weight and a two-ounce weight is clearly enough appreciable when we lift the two1 but one cannot discriminate in the same way between a five-pound weight and a weight of one ounce over five pounds4 ,this last example1 and similar ones for the other senses1 gave ,weber the clew to his novel experiments4 ,reflection upon every-day experiences made it clear to him that whenever we consider two visual sensations1 or two auditory sensations1 or two sensations of weight1 in comparison one with another1 there is always a limit to the keenness of our discrimination1 and that this degree of keenness varies1 as in the case of the weights just cited1 with the magnitude of the exciting cause4 ,weber determined to see whether these common experiences could be brought within the pale of a general law4 ,his method consisted of making long series of experiments aimed at the determination1 in each case1 of what came to be spoken of as the least observable difference between the stimuli4 ,thus if one holds an ounce weight in each hand1 and has tiny weights added to one of them1 grain by grain1 one does not at first perceive a difference2 but presently1 on the addition of a certain grain1 he does become aware of the difference4 ,noting now how many grains have been added to produce this effect1 we have the weight which represents the least appreciable difference when the standard is one ounce4 ,now repeat the experiment1 but let the weights be each of five pounds4 ,clearly in this case we shall be obliged to add not grains1 but drachms1 before a difference between the two heavy weights is perceived4 ,but whatever the exact amount added1 that amount represents the stimulus producing a just-perceivable sensation of difference when the standard is five pounds4 ,and so on for indefinite series of weights of varying magnitudes4 ,now came ,weber's curious discovery4 ,not only did he find that in repeated experiments with the same pair of weights the measure of just-perceivable difference remained approximately fixed1 but he found1 further1 that a remarkable fixed relation exists between the stimuli of different magnitude4 ,if1 for example1 he had found it necessary1 in the case of the ounce weights1 to add one-fiftieth of an ounce to the one before a difference was detected1 he found also1 in the case of the five-pound weights1 that one-fiftieth of five pounds must be added before producing the same result4 ,and so of all other weights2 the amount added to produce the stimulus of least-appreciable difference always bore the same mathematical relation to the magnitude of the weight used1 be that magnitude great or small4 ,weber found that the same thing holds good for the stimuli of the sensations of sight and of hearing1 the differential stimulus bearing always a fixed ratio to the total magnitude of the stimuli4 ,here1 then1 was the law he had sought4 ,weber's results were definite enough and striking enough1 yet they failed to attract any considerable measure of attention until they were revived and extended by ,fechner and brought before the world in the famous work on psycho-physics4 ,then they precipitated a veritable melee4 ,fechner had not alone verified the earlier results 7with certain limitations not essential to the present consideration71 but had invented new methods of making similar tests1 and had reduced the whole question to mathematical treatment4 ,he pronounced ,weber's discovery the fundamental law of psycho-physics4 ,in honor of the discoverer1 he christened it ,weber's ,law4 ,he clothed the law in words and in mathematical formulae1 and1 so to say1 launched it full tilt at the heads of the psychological world4 ,it made a fine commotion1 be assured1 for it was the first widely heralded bulletin of the new psychology in its march upon the strongholds of the time-honored metaphysics4 ,the accomplishments of the microscopists and the nerve physiologists had been but preliminary--mere border skirmishes of uncertain import4 ,but here was proof that the iconoclastic movement meant to invade the very heart of the sacred territory of mind--a territory from which tangible objective fact had been supposed to be forever barred4 ,,physiological ,,psychology ,hardly had the alarm been sounded1 however1 before a new movement was made4 ,while ,fechner's book was fresh from the press1 steps were being taken to extend the methods of the physicist in yet another way to the intimate processes of the mind4 ,as ,helmholtz had shown the rate of nervous impulsion along the nerve tract to be measurable1 it was now sought to measure also the time required for the central nervous mechanism to perform its work of receiving a message and sending out a response4 ,this was coming down to the very threshold of mind4 ,the attempt was first made by ,professor ,donders in #ahfa1 but definitive results were only obtained after many years of experiment on the part of a host of observers4 ,the chief of these1 and the man who has stood in the forefront of the new movement and has been its recognized leader throughout the remainder of the century1 is ,dr4 ,wilhelm ,wundt1 of ,leipzig4 ,the task was not easy1 but1 in the long run1 it was accomplished4 ,not alone was it shown that the nerve centre requires a measurable time for its operations1 but much was learned as to conditions that modify this time4 ,thus it was found that different persons vary in the rate of their central nervous activity--which explained the personal equation that the astronomer ,bessel had noted a half-century before4 ,it was found1 too1 that the rate of activity varies also for the same person under different conditions1 becoming retarded1 for example1 under influence of fatigue1 or in case of certain diseases of the brain4 ,all details aside1 the essential fact emerges1 as an experimental demonstration1 that the intellectual processes--sensation1 apperception1 volition--are linked irrevocably with the activities of the central nervous tissues1 and that these activities1 like all other physical processes1 have a time element4 ,to that old school of psychologists1 who scarcely cared more for the human head than for the heels--being interested only in the mind--such a linking of mind and body as was thus demonstrated was naturally disquieting4 ,but whatever the inferences1 there was no escaping the facts4 ,of course this new movement has not been confined to ,germany4 ,indeed1 it had long had exponents elsewhere4 ,thus in ,england1 a full century earlier1 ,dr4 ,hartley had championed the theory of the close and indissoluble dependence of the mind upon the brain1 and formulated a famous vibration theory of association that still merits careful consideration4 ,then1 too1 in ,france1 at the beginning of the century1 there was ,dr4 ,cabanis with his tangible1 if crudely phrased1 doctrine that the brain digests impressions and secretes thought as the stomach digests food and the liver secretes bile4 ,moreover1 ,herbert ,spencer's ,principles of ,psychology1 with its avowed co-ordination of mind and body and its vitalizing theory of evolution1 appeared in #ahee1 half a decade before the work of ,fechner4 ,but these influences1 though of vast educational value1 were theoretical rather than demonstrative1 and the fact remains that the experimental work which first attempted to gauge mental operations by physical principles was mainly done in ,germany4 ,wundt's ,physiological ,psychology1 with its full preliminary descriptions of the anatomy of the nervous system1 gave tangible expression to the growth of the new movement in #ahgd2 and four years later1 with the opening of his laboratory of physiological psychology at the ,university of ,leipzig1 the new psychology may be said to have gained a permanent foothold and to have forced itself into official recognition4 ,from then on its conquest of the world was but a matter of time4 ,it should be noted1 however1 that there is one other method of strictly experimental examination of the mental field1 latterly much in vogue1 which had a different origin4 ,this is the scientific investigation of the phenomena of hypnotism4 ,this subject was rescued from the hands of charlatans1 rechristened1 and subjected to accurate investigation by ,dr4 ,james ,braid1 of ,manchester1 as early as #ahda4 ,but his results1 after attracting momentary attention1 fell from view1 and1 despite desultory efforts1 the subject was not again accorded a general hearing from the scientific world until #ahgh1 when ,dr4 ,charcot took it up at the ,salpetriere1 in ,paris1 followed soon afterwards by ,dr4 ,rudolf ,heidenhain1 of ,breslau1 and a host of other experimenters4 ,the value of the method in the study of mental states was soon apparent4 ,most of ,braid's experiments were repeated1 and in the main his results were confirmed4 ,his explanation of hypnotism1 or artificial somnambulism1 as a self-induced state1 independent of any occult or supersensible influence1 soon gained general credence4 ,his belief that the initial stages are due to fatigue of nervous centres1 usually from excessive stimulation1 has not been supplanted1 though supplemented by notions growing out of the new knowledge as to subconscious mentality in general1 and the inhibitory influence of one centre over another in the central nervous mechanism4 ,,the ,,brain ,,as ,,the ,,organ ,,of ,,mind ,these studies of the psychologists and pathologists bring the relations of mind and body into sharp relief4 ,but even more definite in this regard was the work of the brain physiologists4 ,chief of these1 during the middle period of the century1 was the man who is sometimes spoken of as the father of brain physiology1 ,marie ,jean ,pierre ,flourens1 of the ,jardin des ,plantes of ,paris1 the pupil and worthy successor of ,magendie4 ,his experiments in nerve physiology were begun in the first quarter of the century1 but his local experiments upon the brain itself were not culminated until about #ahdb4 ,at this time the old dispute over phrenology had broken out afresh1 and the studies of ,flourens were aimed1 in part at least1 at the strictly scientific investigation of this troublesome topic4 ,in the course of these studies ,flourens discovered that in the medulla oblongata1 the part of the brain which connects that organ with the spinal cord1 there is a centre of minute size which cannot be injured in the least without causing the instant death of the animal operated upon4 ,it may be added that it is this spot which is reached by the needle of the garroter in ,spanish executions1 and that the same centre also is destroyed when a criminal is successfully hanged1 this time by the forced intrusion of a process of the second cervical vertebra4 ,flourens named this spot the vital knot4 ,its extreme importance1 as is now understood1 is due to the fact that it is the centre of nerves that supply the heart2 but this simple explanation1 annulling the conception of a specific life centre1 was not at once apparent4 ,other experiments of ,flourens seemed to show that the cerebellum is the seat of the centres that co-ordinate muscular activities1 and that the higher intellectual faculties are relegated to the cerebrum4 ,but beyond this1 as regards localization1 experiment faltered4 ,negative results1 as regards specific faculties1 were obtained from all localized irritations of the cerebrum1 and ,flourens was forced to conclude that the cerebral lobe1 while being undoubtedly the seat of higher intellection1 performs its functions with its entire structure4 ,this conclusion1 which incidentally gave a quietus to phrenology1 was accepted generally1 and became the stock doctrine of cerebral physiology for a generation4 ,it will be seen1 however1 that these studies of ,flourens had a double bearing4 ,they denied localization of cerebral functions1 but they demonstrated the localization of certain nervous processes in other portions of the brain4 ,on the whole1 then1 they spoke positively for the principle of localization of function in the brain1 for which a certain number of students contended2 while their evidence against cerebral localization was only negative4 ,there was here and there an observer who felt that this negative testimony was not conclusive4 ,in particular1 the ,german anatomist ,meynert1 who had studied the disposition of nerve tracts in the cerebrum1 was led to believe that the anterior portions of the cerebrum must have motor functions in preponderance2 the posterior positions1 sensory functions4 ,somewhat similar conclusions were reached also by ,dr4 ,hughlings-,jackson1 in ,england1 from his studies of epilepsy4 ,but no positive evidence was forthcoming until #ahfa1 when ,dr4 ,paul ,broca brought before the ,academy of ,medicine in ,paris a case of brain lesion which he regarded as having most important bearings on the question of cerebral localization4 ,the case was that of a patient at the ,bicetre1 who for twenty years had been deprived of the power of speech1 seemingly through loss of memory of words4 ,in #ahfa this patient died1 and an autopsy revealed that a certain convolution of the left frontal lobe of his cerebrum had been totally destroyed by disease1 the remainder of his brain being intact4 ,broca felt that this observation pointed strongly to a localization of the memory of words in a definite area of the brain4 ,moreover1 it transpired that the case was not without precedent4 ,as long ago as #ahbe ,dr4 ,boillard had been led1 through pathological studies1 to locate definitely a centre for the articulation of words in the frontal lobe1 and here and there other observers had made tentatives in the same direction4 ,boillard had even followed the matter up with pertinacity1 but the world was not ready to listen to him4 ,now1 however1 in the half-decade that followed ,broca's announcements1 interest rose to fever-beat1 and through the efforts of ,broca1 ,boillard1 and numerous others it was proved that a veritable centre having a strange domination over the memory of articulate words has its seat in the third convolution of the frontal lobe of the cerebrum1 usually in the left hemisphere4 ,that part of the brain has since been known to the ,english-speaking world as the convolution of ,broca1 a name which1 strangely enough1 the discoverer's compatriots have been slow to accept4 ,this discovery very naturally reopened the entire subject of brain localization4 ,it was but a short step to the inference that there must be other definite centres worth the seeking1 and various observers set about searching for them4 ,in #ahfg a clew was gained by ,eckhard1 who1 repeating a forgotten experiment by ,haller and ,zinn of the previous century1 removed portions of the brain cortex of animals1 with the result of producing convulsions4 ,but the really vital departure was made in #ahgj by the ,german investigators ,fritsch and ,hitzig1 who1 by stimulating definite areas of the cortex of animals with a galvanic current1 produced contraction of definite sets of muscles of the opposite side of the body4 ,these most important experiments1 received at first with incredulity1 were repeated and extended in #ahgc by ,dr4 ,david ,ferrier1 of ,london1 and soon afterwards by a small army of independent workers everywhere1 prominent among whom were ,franck and ,pitres in ,france1 ,munck and ,goltz in ,germany1 and ,horsley and ,schafer in ,england4 ,the detailed results1 naturally enough1 were not at first all in harmony4 ,some observers1 as ,goltz1 even denied the validity of the conclusions in toto4 ,but a consensus of opinion1 based on multitudes of experiments1 soon placed the broad general facts for which ,fritsch and ,hitzig contended beyond controversy4 ,it was found1 indeed1 that the cerebral centres of motor activities have not quite the finality at first ascribed to them by some observers1 since it may often happen that after the destruction of a centre1 with attending loss of function1 there may be a gradual restoration of the lost function1 proving that other centres have acquired the capacity to take the place of the one destroyed4 ,there are limits to this capacity for substitution1 however1 and with this qualification the definiteness of the localization of motor functions in the cerebral cortex has become an accepted part of brain physiology4 ,nor is such localization confined to motor centres4 ,later experiments1 particularly of ,ferrier and of ,munck1 proved that the centres of vision are equally restricted in their location1 this time in the posterior lobes of the brain1 and that hearing has likewise its local habitation4 ,indeed1 there is every reason to believe that each form of primary sensation is based on impressions which mainly come to a definitely localized goal in the brain4 ,but all this1 be it understood1 has no reference to the higher forms of intellection4 ,all experiment has proved futile to localize these functions1 except indeed to the extent of corroborating the familiar fact of their dependence upon the brain1 and1 somewhat problematically1 upon the anterior lobes of the cerebrum in particular4 ,but this is precisely what should be expected1 for the clearer insight into the nature of mental processes makes it plain that in the main these alleged faculties are not in themselves localized4 ,thus1 for example1 the faculty of language is associated irrevocably with centres of vision1 of hearing1 and of muscular activity1 to go no further1 and only becomes possible through the association of these widely separated centres4 ,the destruction of ,broca's centre1 as was early discovered1 does not altogether deprive a patient of his knowledge of language4 ,he may be totally unable to speak 7though as to this there are all degrees of variation71 and yet may comprehend what is said to him1 and be able to read1 think1 and even write correctly4 ,thus it appears that ,broca's centre is peculiarly bound up with the capacity for articulate speech1 but is far enough from being the seat of the faculty of language in its entirety4 ,in a similar way1 most of the supposed isolated faculties of higher intellection appear1 upon clearer analysis1 as complex aggregations of primary sensations1 and hence necessarily dependent upon numerous and scattered centres4 ,some faculties1 as memory and volition1 may be said in a sense to be primordial endowments of every nerve cell--even of every body cell4 ,indeed1 an ultimate analysis relegates all intellection1 in its primordial adumbrations1 to every particle of living matter4 ,but such refinements of analysis1 after all1 cannot hide the fact that certain forms of higher intellection involve a pretty definite collocation and elaboration of special sensations4 ,such specialization1 indeed1 seems a necessary accompaniment of mental evolution4 ,that every such specialized function has its localized centres of co-ordination1 of some such significance as the demonstrated centres of articulate speech1 can hardly be in doubt--though this1 be it understood1 is an induction1 not as yet a demonstration4 ,in other words1 there is every reason to believe that numerous centres1 in this restricted sense1 exist in the brain that have as yet eluded the investigator4 ,indeed1 the current conception regards the entire cerebral cortex as chiefly composed of centres of ultimate co-ordination of impressions1 which in their cruder form are received by more primitive nervous tissues--the basal ganglia1 the cerebellum and medulla1 and the spinal cord4 ,this1 of course1 is equivalent to postulating the cerebral cortex as the exclusive seat of higher intellection4 ,this proposition1 however1 to which a safe induction seems to lead1 is far afield from the substantiation of the old conception of brain localization1 which was based on faulty psychology and equally faulty inductions from few premises4 ,the details of ,gall's system1 as propounded by generations of his mostly unworthy followers1 lie quite beyond the pale of scientific discussion4 ,yet1 as ,i have said1 a germ of truth was there--the idea of specialization of cerebral functions--and modern investigators have rescued that central conception from the phrenological rubbish heap in which its discoverer unfortunately left it buried4 ,,the ,,minute ,,structure ,,of ,,the ,,brain ,the common ground of all these various lines of investigations of pathologist1 anatomist1 physiologist1 physicist1 and psychologist is1 clearly1 the central nervous system--the spinal cord and the brain4 ,the importance of these structures as the foci of nervous and mental activities has been recognized more and more with each new accretion of knowledge1 and the efforts to fathom the secrets of their intimate structure has been unceasing4 ,for the earlier students1 only the crude methods of gross dissections and microscopical inspection were available4 ,these could reveal something1 but of course the inner secrets were for the keener insight of the microscopist alone4 ,and even for him the task of investigation was far from facile1 for the central nervous tissues are the most delicate and fragile1 and on many accounts the most difficult of manipulation of any in the body4 ,special methods1 therefore1 were needed for this essay1 and brain histology has progressed by fitful impulses1 each forward jet marking the introduction of some ingenious improvement of mechanical technique1 which placed a new weapon in the hands of the investigators4 ,the very beginning was made in #ahbd by ,rolando1 who first thought of cutting chemically hardened pieces of brain tissues into thin sections for microscopical examination--the basal structure upon which almost all the later advances have been conducted4 ,muller presently discovered that bichromate of potassium in solution makes the best of fluids for the preliminary preservation and hardening of the tissues4 ,stilling1 in #ahdb1 perfected the method by introducing the custom of cutting a series of consecutive sections of the same tissue1 in order to trace nerve tracts and establish spacial relations4 ,then from time to time mechanical ingenuity added fresh details of improvement4 ,it was found that pieces of hardened tissue of extreme delicacy can be made better subject to manipulation by being impregnated with collodion or celloidine and embedded in paraffine4 ,latterly it has become usual to cut sections also from fresh tissues1 unchanged by chemicals1 by freezing them suddenly with vaporized ether or1 better1 carbonic acid4 ,by these methods1 and with the aid of perfected microtomes1 the worker of recent periods avails himself of sections of brain tissues of a tenuousness which the early investigators could not approach4 ,but more important even than the cutting of thin sections is the process of making the different parts of the section visible1 one tissue differentiated from another4 ,the thin section1 as the early workers examined it1 was practically colorless1 and even the crudest details of its structure were made out with extreme difficulty4 ,remak did1 indeed1 manage to discover that the brain tissue is cellular1 as early as #ahcc1 and ,ehrenberg in the same year saw that it is also fibrillar1 but beyond this no great advance was made until #aheh1 when a sudden impulse was received from a new process introduced by ,gerlach4 ,the process itself was most simple1 consisting essentially of nothing more than the treatment of a microscopical section with a solution of carmine4 ,but the result was wonderful1 for when such a section was placed under the lens it no longer appeared homogeneous4 ,sprinkled through its substance were seen irregular bodies that had taken on a beautiful color1 while the matrix in which they were embedded remained unstained4 ,in a word1 the central nerve cell had sprung suddenly into clear view4 ,a most interesting body it proved1 this nerve cell1 or ganglion cell1 as it came to be called4 ,it was seen to be exceedingly minute in size1 requiring high powers of the microscope to make it visible4 ,it exists in almost infinite numbers1 not1 however1 scattered at random through the brain and spinal cord4 ,on the contrary1 it is confined to those portions of the central nervous masses which to the naked eye appear gray in color1 being altogether wanting in the white substance which makes up the chief mass of the brain4 ,even in the gray matter1 though sometimes thickly distributed1 the ganglion cells are never in actual contact one with another2 they always lie embedded in intercellular tissues1 which came to be known1 following ,virchow1 as the neuroglia4 ,each ganglion cell was seen to be irregular in contour1 and to have jutting out from it two sets of minute fibres1 one set relatively short1 indefinitely numerous1 and branching in every direction2 the other set limited in number1 sometimes even single1 and starting out directly from the cell as if bent on a longer journey4 ,the numerous filaments came to be known as protoplasmic processes2 the other fibre was named1 after its discoverer1 the axis cylinder of ,deiters4 ,it was a natural inference1 though not clearly demonstrable in the sections1 that these filamentous processes are the connecting links between the different nerve cells and also the channels of communication between nerve cells and the periphery of the body4 ,the white substance of brain and cord1 apparently1 is made up of such connecting fibres1 thus bringing the different ganglion cells everywhere into communication one with another4 ,in the attempt to trace the connecting nerve tracts through this white substance by either macroscopical or microscopical methods1 most important aid is given by a method originated by ,waller in #aheb4 ,earlier than that1 in #ahci1 ,nasse had discovered that a severed nerve cord degenerates in its peripheral portions4 ,waller discovered that every nerve fibre1 sensory or motor1 has a nerve cell to or from which it leads1 which dominates its nutrition1 so that it can only retain its vitality while its connection with that cell is intact4 ,such cells he named trophic centres4 ,certain cells of the anterior part of the spinal cord1 for example1 are the trophic centres of the spinal motor nerves4 ,other trophic centres1 governing nerve tracts in the spinal cord itself1 are in the various regions of the brain4 ,it occurred to ,waller that by destroying such centres1 or by severing the connection at various regions between a nervous tract and its trophic centre1 sharply defined tracts could be made to degenerate1 and their location could subsequently be accurately defined1 as the degenerated tissues take on a changed aspect1 both to macroscopical and microscopical observation4 ,recognition of this principle thus gave the experimenter a new weapon of great efficiency in tracing nervous connections4 ,moreover1 the same principle has wide application in case of the human subject in disease1 such as the lesion of nerve tracts or the destruction of centres by localized tumors1 by embolisms1 or by traumatisms4 ,all these various methods of anatomical examination combine to make the conclusion almost unavoidable that the central ganglion cells are the veritable centres of nervous activity to which so many other lines of research have pointed4 ,the conclusion was strengthened by experiments of the students of motor localization1 which showed that the veritable centres of their discovery lie1 demonstrably1 in the gray cortex of the brain1 not in the white matter4 ,but the full proof came from pathology4 ,at the hands of a multitude of observers it was shown that in certain well-known diseases of the spinal cord1 with resulting paralysis1 it is the ganglion cells themselves that are found to be destroyed4 ,similarly1 in the case of sufferers from chronic insanities1 with marked dementia1 the ganglion cells of the cortex of the brain are found to have undergone degeneration4 ,the brains of paretics in particular show such degeneration1 in striking correspondence with their mental decadence4 ,the position of the ganglion cell as the ultimate centre of nervous activities was thus placed beyond dispute4 ,meantime1 general acceptance being given the histological scheme of ,gerlach1 according to which the mass of the white substance of the brain is a mesh-work of intercellular fibrils1 a proximal idea seemed attainable of the way in which the ganglionic activities are correlated1 and1 through association1 built up1 so to speak1 into the higher mental processes4 ,such a conception accorded beautifully with the ideas of the associationists1 who had now become dominant in psychology4 ,but one standing puzzle attended this otherwise satisfactory correlation of anatomical observations and psychic analyses4 ,it was this3 ,since1 according to the histologist1 the intercellular fibres1 along which impulses are conveyed1 connect each brain cell1 directly or indirectly1 with every other brain cell in an endless mesh-work1 how is it possible that various sets of cells may at times be shut off from one another8 ,such isolation must take place1 for all normal ideation depends for its integrity quite as much upon the shutting-out of the great mass of associations as upon the inclusion of certain other associations4 ,for example1 a student in solving a mathematical problem must for the moment become quite oblivious to the special associations that have to do with geography1 natural history1 and the like4 ,but does histology give any clew to the way in which such isolation may be effected8 ,attempts were made to find an answer through consideration of the very peculiar character of the blood-supply in the brain4 ,here1 as nowhere else1 the terminal twigs of the arteries are arranged in closed systems1 not anastomosing freely with neighboring systems4 ,clearly1 then1 a restricted area of the brain may1 through the controlling influence of the vasomotor nerves1 be flushed with arterial blood while neighboring parts remain relatively anaemic4 ,and since vital activities unquestionably depend in part upon the supply of arterial blood1 this peculiar arrangement of the vascular mechanism may very properly be supposed to aid in the localized activities of the central nervous ganglia4 ,but this explanation left much to be desired--in particular when it is recalled that all higher intellection must in all probability involve multitudes of widely scattered centres4 ,no better explanation was forthcoming1 however1 until the year #ahhi1 when of a sudden the mystery was cleared away by a fresh discovery4 ,not long before this the ,italian histologist ,dr4 ,camille ,golgi had discovered a method of impregnating hardened brain tissues with a solution of nitrate of silver1 with the result of staining the nerve cells and their processes almost infinitely better than was possible by the methods of ,gerlach1 or by any of the multiform methods that other workers had introduced4 ,now for the first time it became possible to trace the cellular prolongations definitely to their termini1 for the finer fibrils had not been rendered visible by any previous method of treatment4 ,golgi himself proved that the set of fibrils known as protoplasmic prolongations terminate by free extremities1 and have no direct connection with any cell save the one from which they spring4 ,he showed also that the axis cylinders give off multitudes of lateral branches not hitherto suspected4 ,but here he paused1 missing the real import of the discovery of which he was hard on the track4 ,it remained for the ,spanish histologist ,dr4 ,s4 ,ramon y ,cajal to follow up the investigation by means of an improved application of ,golgi's method of staining1 and to demonstrate that the axis cylinders1 together with all their collateral branches1 though sometimes extending to a great distance1 yet finally terminate1 like the other cell prolongations1 in arborescent fibrils having free extremities4 ,in a word1 it was shown that each central nerve cell1 with its fibrillar offshoots1 is an isolated entity4 ,instead of being in physical connection with a multitude of other nerve cells1 it has no direct physical connection with any other nerve cell whatever4 ,when ,dr4 ,cajal announced his discovery1 in #ahhi1 his revolutionary claims not unnaturally amazed the mass of histologists4 ,there were some few of them1 however1 who were not quite unprepared for the revelation2 in particular ,his1 who had half suspected the independence of the cells1 because they seemed to develop from dissociated centres2 and ,forel1 who based a similar suspicion on the fact that he had never been able actually to trace a fibre from one cell to another4 ,these observers then came readily to repeat ,cajal's experiments4 ,so also did the veteran histologist ,kolliker1 and soon afterwards all the leaders everywhere4 ,the result was a practically unanimous confirmation of the ,spanish histologist's claims1 and within a few months after his announcements the old theory of union of nerve cells into an endless mesh-work was completely discarded1 and the theory of isolated nerve elements--the theory of neurons1 as it came to be called--was fully established in its place4 ,as to how these isolated nerve cells functionate1 ,dr4 ,cajal gave the clew from the very first1 and his explanation has met with universal approval4 ,in the modified view1 the nerve cell retains its old position as the storehouse of nervous energy4 ,each of the filaments jutting out from the cell is held1 as before1 to be indeed a transmitter of impulses1 but a transmitter that operates intermittently1 like a telephone wire that is not always connected1 and1 like that wire1 the nerve fibril operates by contact and not by continuity4 ,under proper stimulation the ends of the fibrils reach out1 come in contact with other end fibrils of other cells1 and conduct their destined impulse4 ,again they retract1 and communication ceases for the time between those particular cells4 ,meantime1 by a different arrangement of the various conductors1 different sets of cells are placed in communication1 different associations of nervous impulses induced1 different trains of thought engendered4 ,each fibril when retracted becomes a non-conductor1 but when extended and in contact with another fibril1 or with the body of another cell1 it conducts its message as readily as a continuous filament could do--precisely as in the case of an electric wire4 ,this conception1 founded on a most tangible anatomical basis1 enables us to answer the question as to how ideas are isolated1 and also1 as ,dr4 ,cajal points out1 throws new light on many other mental processes4 ,one can imagine1 for example1 by keeping in mind the flexible nerve prolongations1 how new trains of thought may be engendered through novel associations of cells2 how facility of thought or of action in certain directions is acquired through the habitual making of certain nerve-cell connections2 how certain bits of knowledge may escape our memory and refuse to be found for a time because of a temporary incapacity of the nerve cells to make the proper connections1 and so on indefinitely4 ,if one likens each nerve cell to a central telephone office1 each of its filamentous prolongations to a telephone wire1 one can imagine a striking analogy between the modus operandi of nervous processes and of the telephone system4 ,the utility of new connections at the central office1 the uselessness of the mechanism when the connections cannot be made1 the wires in use that retard your message1 perhaps even the crossing of wires1 bringing you a jangle of sounds far different from what you desire--all these and a multiplicity of other things that will suggest themselves to every user of the telephone may be imagined as being almost ludicrously paralleled in the operations of the nervous mechanism4 ,and that parallel1 startling as it may seem1 is not a mere futile imagining4 ,it is sustained and rendered plausible by a sound substratum of knowledge of the anatomical conditions under which the central nervous mechanism exists1 and in default of which1 as pathology demonstrates with no less certitude1 its functionings are futile to produce the normal manifestations of higher intellection4 ,x4 ,,the ,,new ,,science ,,of ,,oriental ,,archaeology ,,how ,,the ,,riddle ,,of ,,the ,,sphinx ,,was ,,read ,conspicuously placed in the great hall of ,egyptian antiquities in the ,british ,museum is a wonderful piece of sculpture known as the ,rosetta ,stone4 ,i doubt if any other piece in the entire exhibit attracts so much attention from the casual visitor as this slab of black basalt on its telescope-like pedestal4 ,the hall itself1 despite its profusion of strangely sculptured treasures1 is never crowded1 but before this stone you may almost always find some one standing1 gazing with more or less of discernment at the strange characters that are graven neatly across its upturned1 glass-protected face4 ,a glance at this graven surface suffices to show that three sets of inscriptions are recorded there4 ,the upper one1 occupying about one-fourth of the surface1 is a pictured scroll1 made up of chains of those strange outlines of serpents1 hawks1 lions1 and so on1 which are recognized1 even by the least initiated1 as hieroglyphics4 ,the middle inscription1 made up of lines1 angles1 and half-pictures1 one might surmise to be a sort of abbreviated or short-hand hieroglyphic4 ,the third or lower inscription is ,greek--obviously a thing of words4 ,if the screeds above be also made of words1 only the elect have any way of proving the fact4 ,fortunately1 however1 even the least scholarly observer is left in no doubt as to the real import of the thing he sees1 for an obliging ,english label tells us that these three inscriptions are renderings of the same message1 and that this message is a decree of the priests of ,memphis conferring divine honors on ,ptolemy ,v4 7,epiphenes71 ,king of ,egypt1 ,b4,c4 #aie4 ,the label goes on to state that the upper inscription 7of which1 unfortunately1 only part of the last dozen lines or so remains1 the slab being broken7 is in the ,egyptian language1 in hieroglyphics1 or writing of the priests2 the second inscription in the same language is in ,demotic1 or the writing of the people2 and the third the ,greek language and character4 ,following this is a brief biography of the ,rosetta ,stone itself1 as follows3 ,the stone was found by the ,french in #agih among the ruins of ,fort ,saint ,julien1 near the ,rosetta mouth of the ,nile4 ,it passed into the hands of the ,british by the treaty of ,alexandria1 and was deposited in the ,british ,museum in the year #ahja4 ,there is a whole volume of history in that brief inscription--and a bitter sting thrown in1 if the reader chance to be a ,frenchman4 ,yet the facts involved could scarcely be suggested more modestly4 ,they are recorded much more bluntly in a graven inscription on the side of the stone1 which reads3 ,captured in ,egypt by the ,british ,army1 #ahja4 ,no ,frenchman could read those words without a veritable sinking of the heart4 ,the value of the ,rosetta ,stone depended on the fact that it gave promise1 even when casually inspected1 of furnishing a key to the centuries-old mystery of the hieroglyphics4 ,for two thousand years the secret of these strange markings had been forgotten4 ,nowhere in the world--quite as little in ,egypt as elsewhere--had any man the slightest clew to their meaning2 there were those who even doubted whether these droll picturings really had any specific meaning1 questioning whether they were not rather vague symbols of esoteric religious import and nothing more4 ,and it was the ,rosetta ,stone that gave the answer to these doubters and restored to the world a lost language and a forgotten literature4 ,the trustees of the museum recognized at once that the problem of the ,rosetta ,stone was one on which the scientists of the world might well exhaust their ingenuity1 and promptly published to the world a carefully lithographed copy of the entire inscription1 so that foreign scholarship had equal opportunity with the ,british to try at the riddle4 ,it was an ,englishman1 however1 who first gained a clew to the solution4 ,this was none other than the extraordinary ,dr4 ,thomas ,young1 the demonstrator of the vibratory nature of light4 ,young's specific discoveries were these3 7#a7 ,that many of the pictures of the hieroglyphics stand for the names of the objects actually delineated2 7#b7 that other pictures are sometimes only symbolic2 7#c7 that plural numbers are represented by repetition2 7#d7 that numerals are represented by dashes2 7#e7 that hieroglyphics may read either from the right or from the left1 but always from the direction in which the animal and human figures face2 7#f7 that proper names are surrounded by a graven oval ring1 making what he called a cartouche2 7#g7 that the cartouches of the preserved portion of the ,rosetta ,stone stand for the name of ,ptolemy alone2 7#h7 that the presence of a female figure after such cartouches in other inscriptions always denotes the female sex2 7#i7 that within the cartouches the hieroglyphic symbols have a positively phonetic value1 either alphabetic or syllabic2 and 7#aj7 that several different characters may have the same phonetic value4 ,just what these phonetic values are ,young pointed out in the case of fourteen characters representing nine sounds1 six of which are accepted to-day as correctly representing the letters to which he ascribed them1 and the three others as being correct regarding their essential or consonant element4 ,it is clear1 therefore1 that he was on the right track thus far1 and on the very verge of complete discovery4 ,but1 unfortunately1 he failed to take the next step1 which would have been to realize that the same phonetic values which were given to the alphabetic characters within the cartouches were often ascribed to them also when used in the general text of an inscription2 in other words1 that the use of an alphabet was not confined to proper names4 ,this was the great secret which ,young missed and which his ,french successor1 ,jean ,francois ,champollion1 working on the foundation that ,young had laid1 was enabled to ferret out4 ,young's initial studies of the ,rosetta ,stone were made in #ahad2 his later publication bore date of #ahai4 ,champollion's first announcement of results came in #ahbb2 his second and more important one in #ahbd4 ,by this time1 through study of the cartouches of other inscriptions1 ,champollion had made out almost the complete alphabet1 and the riddle of the ,sphinx was practically solved4 ,he proved that the ,egyptians had developed a relatively complete alphabet 7mostly neglecting the vowels1 as early ,semitic alphabets did also7 centuries before the ,phoenicians were heard of in history4 ,what relation this alphabet bore to the ,phoenician we shall have occasion to ask in another connection2 for the moment it suffices to know that those strange pictures of the ,egyptian scroll are really letters4 ,even this statement1 however1 must be in a measure modified4 ,these pictures are letters and something more4 ,some of them are purely alphabetical in character and some are symbolic in another way4 ,some characters represent syllables4 ,others stand sometimes as mere representatives of sounds1 and again1 in a more extended sense1 as representations of things1 such as all hieroglyphics doubtless were in the beginning4 ,in a word1 this is an alphabet1 but not a perfected alphabet1 such as modern nations are accustomed to2 hence the enormous complications and difficulties it presented to the early investigators4 ,champollion did not live to clear up all these mysteries4 ,his work was taken up and extended by his pupil ,rossellini1 and in particular by ,dr4 ,richard ,lepsius in ,germany1 followed by ,m4 ,bernouf1 and by ,samuel ,birch of the ,british ,museum1 and more recently by such well-known ,egyptologists as ,,mm4 ,maspero and ,mariette and ,chabas1 in ,france1 ,dr4 ,brugsch1 in ,germany1 and ,dr4 ,e4 ,wallis ,budge1 the present head of the ,department of ,oriental ,antiquities at the ,british ,museum4 ,but the task of later investigators has been largely one of exhumation and translation of records rather than of finding methods4 ,,treasures ,,from ,,nineveh ,the most casual wanderer in the ,british ,museum can hardly fail to notice two pairs of massive sculptures1 in the one case winged bulls1 in the other winged lions1 both human-headed1 which guard the entrance to the ,egyptian hall1 close to the ,rosetta ,stone4 ,each pair of these weird creatures once guarded an entrance to the palace of a king in the famous city of ,nineveh4 ,as one stands before them his mind is carried back over some twenty-seven intervening centuries1 to the days when the ,cedar of ,lebanon was fair in his greatness and the scourge of ,israel4 ,the very ,sculptures before us1 for example1 were perhaps seen by ,jonah when he made that famous voyage to ,nineveh some seven or eight hundred years ,b4,c4 ,a little later the ,babylonian and the ,mede revolted against ,assyrian tyranny and descended upon the fair city of ,nineveh1 and almost literally levelled it to the ground4 ,but these great sculptures1 among other things1 escaped destruction1 and at once hidden and preserved by the accumulating debris of the centuries1 they stood there age after age1 their very existence quite forgotten4 ,when ,xenophon marched past their site with the ill-starred expedition of the ten thousand1 in the year #djj ,b4,c41 he saw only a mound which seemed to mark the site of some ancient ruin2 but the ,greek did not suspect that he looked upon the site of that city which only two centuries before had been the mistress of the world4 ,so ephemeral is fame6 ,and yet the moral scarcely holds in the sequel2 for we of to-day1 in this new1 undreamed-of ,western world1 behold these mementos of ,assyrian greatness fresh from their twenty-five hundred years of entombment1 and with them records which restore to us the history of that long-forgotten people in such detail as it was not known to any previous generation since the fall of ,nineveh4 ,for two thousand five hundred years no one saw these treasures or knew that they existed4 ,one hundred generations of men came and went without once pronouncing the name of kings ,shalmaneser or ,asumazirpal or ,asurbanipal4 ,and to-day1 after these centuries of oblivion1 these names are restored to history1 and1 thanks to the character of their monuments1 are assured a permanency of fame that can almost defy time itself4 ,it would be nothing strange1 but rather in keeping with their previous mutations of fortune1 if the names of ,asurnazirpal and ,asurbanipal should be familiar as household words to future generations that have forgotten the existence of an ,alexander1 a ,caesar1 and a ,napoleon4 ,for when ,macaulay's prospective ,new ,zealander explores the ruins of the ,british ,museum the records of the ancient ,assyrians will presumably still be there unscathed1 to tell their story as they have told it to our generation1 though every manuscript and printed book may have gone the way of fragile textures4 ,but the past of the ,assyrian sculptures is quite necromantic enough without conjuring for them a necromantic future4 ,the story of their restoration is like a brilliant romance of history4 ,prior to the middle of this century the inquiring student could learn in an hour or so all that was known in fact and in fable of the renowned city of ,nineveh4 ,he had but to read a few chapters of the ,bible and a few pages of ,diodorus to exhaust the important literature on the subject4 ,if he turned also to the pages of ,herodotus and ,xenophon1 of ,justin and ,aelian1 these served chiefly to confirm the suspicion that the ,greeks themselves knew almost nothing more of the history of their famed ,oriental forerunners4 ,the current fables told of a first ,king ,ninus and his wonderful queen ,semiramis2 of ,sennacherib the conqueror2 of the effeminate ,sardanapalus1 who neglected the warlike ways of his ancestors but perished gloriously at the last1 with ,nineveh itself1 in a self-imposed holocaust4 ,and that was all4 ,how much of this was history1 how much myth1 no man could say2 and for all any one suspected to the contrary1 no man could ever know4 ,and to-day the contemporary records of the city are before us in such profusion as no other nation of antiquity1 save ,egypt alone1 can at all rival4 ,whole libraries of ,assyrian books are at hand that were written in the seventh century before our era4 ,these1 be it understood1 are the original books themselves1 not copies4 ,the author of that remote time appeals to us directly1 hand to eye1 without intermediary transcriber4 ,and there is not a line of any ,hebrew or ,greek manuscript of a like age that has been preserved to us2 there is little enough that can match these ancient books by a thousand years4 ,when one reads ,moses or ,isaiah1 ,homer1 ,hesiod1 or ,herodotus1 he is but following the transcription--often unquestionably faulty and probably never in all parts perfect--of successive copyists of later generations4 ,the oldest known copy of the ,bible1 for example1 dates probably from the fourth century ,a4,d41 a thousand years or more after the last ,assyrian records were made and read and buried and forgotten4 ,there was at least one king of ,assyria--namely1 ,asurbanipal1 whose palace boasted a library of some ten thousand volumes--a library1 if you please1 in which the books were numbered and shelved systematically1 and classified and cared for by an official librarian4 ,if you would see some of the documents of this marvellous library you have but to step past the winged lions of ,asurnazirpal and enter the ,assyrian hall just around the corner from the ,rosetta ,stone4 ,indeed1 the great slabs of stone from which the lions themselves are carved are in a sense books1 inasmuch as there are written records inscribed on their surface4 ,a glance reveals the strange characters in which these records are written1 graven neatly in straight lines across the stone1 and looking to casual inspection like nothing so much as random flights of arrow-heads4 ,the resemblance is so striking that this is sometimes called the arrow-head character1 though it is more generally known as the wedge or cuneiform character4 ,the inscriptions on the flanks of the lions are1 however1 only makeshift books4 ,but the veritable books are no farther away than the next room beyond the hall of ,asurnazirpal4 ,they occupy part of a series of cases placed down the centre of this room4 ,perhaps it is not too much to speak of this collection as the most extraordinary set of documents of all the rare treasures of the ,british ,museum1 for it includes not books alone1 but public and private letters1 business announcements1 marriage contracts--in a word1 all the species of written records that enter into the every-day life of an intelligent and cultured community4 ,but by what miracle have such documents been preserved through all these centuries8 ,a glance makes the secret evident4 ,it is simply a case of time-defying materials4 ,each one of these ,assyrian documents appears to be1 and in reality is1 nothing more or less than an inscribed fragment of brick1 having much the color and texture of a weathered terra-cotta tile of modern manufacture4 ,these slabs are usually oval or oblong in shape1 and from two or three to six or eight inches in length and an inch or so in thickness4 ,each of them was originally a portion of brick-clay1 on which the scribe indented the flights of arrowheads with some sharp-cornered instrument1 after which the document was made permanent by baking4 ,they are somewhat fragile1 of course1 as all bricks are1 and many of them have been more or less crumbled in the destruction of the palace at ,nineveh2 but to the ravages of mere time they are as nearly invulnerable as almost anything in nature4 ,hence it is that these records of a remote civilization have been preserved to us1 while the similar records of such later civilizations as the ,grecian have utterly perished1 much as the flint implements of the cave-dweller come to us unchanged1 while the iron implements of a far more recent age have crumbled away4 ,,how ,,the ,,records ,,were ,,read ,after all1 then1 granted the choice of materials1 there is nothing so very extraordinary in the mere fact of preservation of these ancient records4 ,to be sure1 it is vastly to the credit of nineteenth-century enterprise to have searched them out and brought them back to light4 ,but the real marvel in connection with them is the fact that nineteenth-century scholarship should have given us1 not the material documents themselves1 but a knowledge of their actual contents4 ,the flight of arrow-heads on wall or slab or tiny brick have surely a meaning2 but how shall we guess that meaning8 ,these must be words2 but what words8 ,the hieroglyphics of the ,egyptians were mysterious enough in all conscience2 yet1 after all1 their symbols have a certain suggestiveness1 whereas there is nothing that seems to promise a mental leverage in the unbroken succession of these cuneiform dashes4 ,yet the ,assyrian scholar of to-day can interpret these strange records almost as readily and as surely as the classical scholar interprets a ,greek manuscript4 ,and this evidences one of the greatest triumphs of nineteenth-century scholarship1 for within almost two thousand years no man has lived1 prior to our century1 to whom these strange inscriptions would not have been as meaningless as they are to the most casual stroller who looks on them with vague wonderment here in the museum to-day4 ,for the ,assyrian language1 like the ,egyptian1 was veritably a dead language2 not1 like ,greek and ,latin1 merely passed from practical every-day use to the closet of the scholar1 but utterly and absolutely forgotten by all the world4 ,such being the case1 it is nothing less than marvellous that it should have been restored4 ,it is but fair to add that this restoration probably never would have been effected1 with ,assyrian or with ,egyptian1 had the language in dying left no cognate successor2 for the powers of modern linguistry1 though great1 are not actually miraculous4 ,but1 fortunately1 a language once developed is not blotted out in toto2 it merely outlives its usefulness and is gradually supplanted1 its successor retaining many traces of its origin4 ,so1 just as ,latin1 for example1 has its living representatives in ,italian and the other ,romance tongues1 the language of ,assyria is represented by cognate ,semitic languages4 ,as it chances1 however1 these have been of aid rather in the later stages of ,assyrian study than at the very outset2 and the first clew to the message of the cuneiform writing came through a slightly different channel4 ,curiously enough1 it was a trilingual inscription that gave the clew1 as in the case of the ,rosetta ,stone1 though with very striking difference withal4 ,the trilingual inscription now in question1 instead of being a small1 portable monument1 covers the surface of a massive bluff at ,behistun in western ,persia4 ,moreover1 all three of its inscriptions are in cuneiform characters1 and all three are in languages that at the beginning of our century were absolutely unknown4 ,this inscription itself1 as a striking monument of unknown import1 had been seen by successive generations4 ,tradition ascribed it1 as we learn from ,ctesias1 through ,diodorus1 to the fabled ,assyrian queen ,semiramis4 ,tradition was quite at fault in this2 but it is only recently that knowledge has availed to set it right4 ,the inscription1 as is now known1 was really written about the year #eae ,b4,c41 at the instance of ,darius ,i41 ,king of ,persia1 some of whose deeds it recounts in the three chief languages of his widely scattered subjects4 ,the man who at actual risk of life and limb copied this wonderful inscription1 and through interpreting it became the veritable father of ,assyriology1 was the ,english general ,sir ,henry ,rawlinson4 ,his feat was another ,british triumph over the same rivals who had competed for the ,rosetta ,stone2 for some ,french explorers had been sent by their government1 some years earlier1 expressly to copy this strange record1 and had reported that it was impossible to reach the inscription4 ,but ,british courage did not find it so1 and in #ahce ,rawlinson scaled the dangerous height and made a paper cast of about half the inscription4 ,diplomatic duties called him away from the task for some years1 but in #ahdh he returned to it and completed the copy of all parts of the inscription that have escaped the ravages of time4 ,and now the material was in hand for a new science1 which ,general ,rawlinson himself soon1 assisted by a host of others1 proceeded to elaborate4 ,the key to the value of this unique inscription lies in the fact that its third language is ancient ,persian4 ,it appears that the ancient ,persians had adopted the cuneiform character from their western neighbors1 the ,assyrians1 but in so doing had made one of those essential modifications and improvements which are scarcely possible to accomplish except in the transition from one race to another4 ,instead of building with the arrow-head a multitude of syllabic characters1 including many homophones1 as had been and continued to be the custom with the ,assyrians1 the ,persians selected a few of these characters and ascribed to them phonetic values that were almost purely alphabetic4 ,in a word1 while retaining the wedge as the basal stroke of their script1 they developed an alphabet1 making the last wonderful analysis of phonetic sounds which even to this day has escaped the ,chinese1 which the ,egyptians had only partially effected1 and which the ,phoenicians were accredited by the ,greeks with having introduced to the ,western world4 ,in addition to this all-essential step1 the ,persians had introduced the minor but highly convenient custom of separating the words of a sentence from one another by a particular mark1 differing in this regard not only from the ,assyrians and ,egyptians1 but from the early ,greek scribes as well4 ,thanks to these simplifications1 the old ,persian language had been practically restored about the beginning of the nineteenth century1 through the efforts of the ,german ,grotefend1 and further advances in it were made just at this time by ,renouf1 in ,france1 and by ,lassen1 in ,germany1 as well as by ,rawlinson himself1 who largely solved the problem of the ,persian alphabet independently4 ,so the ,persian portion of the ,behistun inscription could be at least partially deciphered4 ,this in itself1 however1 would have been no very great aid towards the restoration of the languages of the other portions had it not chanced1 fortunately1 that the inscription is sprinkled with proper names4 ,now proper names1 generally speaking1 are not translated from one language to another1 but transliterated as nearly as the genius of the language will permit4 ,it was the fact that the ,greek word ,ptolemaics was transliterated on the ,rosetta ,stone that gave the first clew to the sounds of the ,egyptian characters4 ,had the upper part of the ,rosetta ,stone been preserved1 on which1 originally1 there were several other names1 ,young would not have halted where he did in his decipherment4 ,but fortune1 which had been at once so kind and so tantalizing in the case of the ,rosetta ,stone1 had dealt more gently with the ,behistun inscriptions2 for no fewer than ninety proper names were preserved in the ,persian portion and duplicated1 in another character1 in the ,assyrian inscription4 ,a study of these gave a clew to the sounds of the ,assyrian characters4 ,the decipherment of this character1 however1 even with this aid1 proved enormously difficult1 for it was soon evident that here it was no longer a question of a nearly perfect alphabet of a few characters1 but of a syllabary of several hundred characters1 including many homophones1 or different forms for representing the same sound4 ,but with the ,persian translation for a guide on the one hand1 and the ,semitic languages1 to which family the ,assyrian belonged1 on the other1 the appalling task was gradually accomplished1 the leading investigators being ,general ,rawlinson1 ,professor ,hincks1 and ,mr4 ,fox-,talbot1 in ,england1 ,professor ,jules ,oppert1 in ,paris1 and ,professor ,julian ,schrader1 in ,germany1 though a host of other scholars soon entered the field4 ,this great linguistic feat was accomplished about the middle of the nineteenth century4 ,but so great a feat was it that many scholars of the highest standing1 including ,joseph ,erneste ,renan1 in ,france1 and ,sir ,g4 ,cornewall ,lewis1 in ,england1 declined at first to accept the results1 contending that the ,assyriologists had merely deceived themselves by creating an arbitrary language4 ,the matter was put to a test in #ahee at the suggestion of ,mr4 ,fox-,talbot1 when four scholars1 one being ,mr4 ,talbot himself and the others ,general ,rawlinson1 ,professor ,hincks1 and ,professor ,oppert1 laid before the ,royal ,asiatic ,society their independent interpretations of a hitherto untranslated ,assyrian text4 ,a committee of the society1 including ,england's greatest historian of the century1 ,george ,grote1 broke the seals of the four translations1 and reported that they found them unequivocally in accord as regards their main purport1 and even surprisingly uniform as regards the phraseology of certain passages--in short1 as closely similar as translations from the obscure texts of any difficult language ever are4 ,this decision gave the work of the ,assyriologists official status1 and the reliability of their method has never since been in question4 ,henceforth ,assyriology was an established science4 ,,appendix ,,reference-,,list ,,chapter ,i4 ,,modern ,,development ,,of ,,the ,,physical ,,sciences 7#a7 ,robert ,boyle1 ,philosophical ,works 7#c vols474 ,london1 #agch4 ,,chapter ,,ii4 ,,the ,,beginnings ,,of ,,modern ,,chemistry 7#a7 ,for a complete account of the controversy called the ,water ,controversy1 see ,the ,life of the ,hon4 ,henry ,cavendish1 by ,george ,wilson1 ,m4,d41 ,f4,r4,s4,e4 ,london1 #ahej4 7#b7 ,henry ,cavendish1 in ,phil4 ,trans4 for #aghd1 ,p4 #aai4 7#c7 ,lives of the ,philosophers of the ,time of ,george ,,iii41 by ,henry1 ,lord ,brougham1 ,f4,r4,s41 p4 #ajf4 ,london1 #ahee4 7#d7 ,experiments and ,observations on ,different ,kinds of ,air1 by ,joseph ,priestley 7#c vols474 ,birmingham1 #gij1 vol4 ,,ii1 pp4 #ajc-ajg4 7#e7 ,lectures on ,experimental ,philosophy1 by ,joseph ,priestley1 lecture ,,iv41 pp4 #ah1 ig4 ,j4 ,johnson1 ,london1 #agid4 7#f7 ,translated from ,scheele's ,om ,brunsten1 eller ,magnesia1 och dess ,egenakaper4 ,stockholm1 #aggd1 and published as ,alembic ,club ,reprints1 ,no4 #ac1 #ahig1 p4 #f4 7#g7 ,according to some writers this was discovered by ,berzelius4 7#h7 ,histoire de la ,chimie1 par ,ferdinand ,hoefer4 ,paris1 #ahfi1 ,vol4 ,,cl1 p4 #bhi4 7#i7 ,elements of ,chemistry1 by ,anton ,laurent ,lavoisier1 translated by ,robert ,kerr1 p4 #h4 ,london and ,edinburgh1 #agij4 7#aj7 ,ibid41 pp4 #dad-daf4 ,,chapter ,,iii4 ,,chemistry ,,since ,,the ,,time ,,of ,,dalton 7#a7 ,sir ,humphry ,davy1 in ,phil4 ,trans41 ,vol4 ,,viii4 ,,chapter ,,iv4 ,,anatomy ,,and ,,physiology ,,in ,,the ,,eighteenth ,,century 7#a7 ,baas1 ,history of ,medicine1 p4 #fib4 7#b7 ,based on ,thomas ,h4 ,huxley's ,presidential ,address to the ,british ,association for the ,advancement of ,science1 #ahgj4 7#c7 ,essays on ,digestion1 by ,james ,carson4 ,london1 #ahcd1 p4 #f4 7#d7 ,ibid41 p4 #g4 7#e7 ,john ,hunter1 ,on the ,digestion of the ,stomach after ,death1 first edition1 pp4 #ahc-ahh4 7#f7 ,erasmus ,darwin1 ,the ,botanic ,garden1 pp4 #ddh-dec4 ,london1 #agii4 ,,chapter ,v4 ,,anatomy ,,and ,,physiology ,,in ,,the ,,nineteenth ,,century 7#a7 ,baron de ,cuvier's ,theory of the ,earth4 ,new ,york1 #ahah1 p4 #abc4 7#b7 ,on the ,organs and ,mode of ,fecundation of ,orchidex and ,asclepiadea1 by ,robert ,brown1 ,esq41 in ,miscellaneous ,botanical ,works4 ,london1 #ahff1 ,vol4 ,i41 pp4 #eaa-ead4 7#c7 ,justin ,liebig1 ,animal ,chemistry4 ,london1 #ahdc1 p4 #ag;f4 ,,chapter ,,vi4 ,,theories ,,of ,,organic ,,evolution 7#a7 ,essay on the ,metamorphoses of ,plants1 by ,goethe1 translated for the present work from ,grundriss einer ,geschichte der ,naturwissenschaften1 by ,friederich ,dannemann 7#b vols474 ,leipzig1 #ahif1 ,vol4 ,i41 p4 #aid4 7#b7 ,the ,temple of ,nature1 or ,the ,origin of ,society1 by ,erasmus ,darwin1 edition published in #ahjg1 p4 #ce4 7#c7 ,baron de ,cuvier1 ,theory of the ,earth4 ,new ,york1 #ahah1 p4#gd4 7,this was the introduction to ,cuvier's great work47 7#d7 ,robert ,chambers1 ,explanations3 a sequel to ,vestiges of ,creation4 ,london1 ,churchill1 #ahde1 pp4 #adh-aec4 ,,chapter ,,vii4 ,,eighteenth-,,century ,,medicine 7#a7 ,condensed from ,dr4 ,boerhaave's ,academical ,lectures on the ,theory of ,physic4 ,london1 #agea1 pp4 #gg1 #gh4 ,boerhaave's lectures were published as ,aphorismi de cognoscendis et curandis ,morbis1 ,leyden1 #agji4 ,on this book ,van ,swieten wrote commentaries filling five volumes4 ,another very celebrated work of ,boerhaave is his ,institutiones et ,experimenta ,chemic1 ,paris1 #agbd1 the germs of this being given as a lecture on his appointment to the chair of chemistry in the ,university of ,leyden in #agah4 7#b7 ,an ,inquiry into the ,causes and ,effects of the ,variola ,vaccine1 etc41 by ,edward ,jenner1 ,m4,d41 ,f4,r4,s41 etc4 ,london1 #agii1 pp4 #b-g4 ,he wrote several other papers1 most of which were communications to the ,royal ,society4 ,his last publication was1 ,on the ,influence of ,artificial ,eruptions in ,certain ,diseases 7,london1 #ahbb71 a subject to which he had given much time and study4 ,,chapter ,,viii4 ,,nineteenth-,,century ,,medicine 7#a7 ,in the introduction to ,corvisart's translation of ,avenbrugger's work4 ,paris1 #ahjh4 7#b7 ,laennec1 ,traite d',auscultation ,mediate4 ,paris1 #ahai4 ,this was ,laennec's chief work1 and was soon translated into several different languages4 ,before publishing this he had written also1 ,propositions sur la doctrine midicale d',hippocrate1 ,paris1 #ahjd1 and ,memoires sur les vers visiculaires1 in the same year4 7#c7 ,researches1 ,chemical and ,philosophical1 chiefly concerning ,nitrous ,oxide or ,dephlogisticated ,nitrous ,air and its ,respiration1 by ,humphry ,davy4 ,london1 #ahjj1 pp4 #dgi-eef4 7#d7 ,ibid4 7#e7 ,for accounts of the discovery of anaesthesia1 see ,report of the ,board of ,trustees of the ,massachusetts ,general ,hospital1 ,boston1 #ahhh4 ,also1 ,the ,ether ,controversy3 ,vindication of the ,hospital ,reports of #ahdh1 by ,n4 ,l ,bowditch1 ,boston1 #ahdh4 ,an excellent account is given in ,littell's ,living ,age1 for ,march1 #ahdh1 written by ,r4 ,h4 ,dana1 ,jr4 ,there are also two ,congressional ,reports on the question of the discovery of etherization1 one for #ahdh1 the other for #aaheb4 7#f7 ,simpson made public this discovery of the anaesthetic properties of chloroform in a paper read before the ,medico-,chirurgical ,society of ,edinburgh1 in ,march1 #ahdg1 about three months after he had first seen a surgical operation performed upon a patient to whom ether had been administered4 7#g7 ,louis ,pasteur1 ,studies on ,fermentation4 ,london1 #ahgj4 7#h7 ,louis ,pasteur1 in ,comptes ,rendus des ,sciences de ,l',academie des ,sciences1 vol4 ,,xcii41 #ahha1 pp4 #dbi-dce4 ,,chapter ,,ix4 ,,the ,,new ,,science ,,of ,,experimental ,,psychology 7#a7 ,bell's communications were made to the ,royal ,society1 but his studies and his discoveries in the field of anatomy of the nervous system were collected and published1 in #ahbd1 as ,an ,exposition of the ,natural ,system of ,nerves of the ,human ,body3 being a ,republication of the ,papers delivered to the ,royal ,society on the ,subject of the ,nerves4 7#b7 ,marshall ,hall1 ,m4,d41 ,f4,r4,s4,l41 ,on the ,reflex ,functions of the ,medulla ,oblongata and the ,medulla ,spinalis1 in ,phil4 ,trans4 of ,royal ,soc41 vol4 ,,xxxiii41 #ahcc4