the modern story of the theory of organic evolution shows certain important dates—1859, 1880, 1894, 1895, 1899 and 1909. these begin with the origin of species and end with the publica-tion of a volume in commemora-tion of its jubilee, when most of the leading students of evolution united to render homage to darwin. the year 1859 has been so often and so worthily treated that it is enough here to say that the fifty years between the issue of the work of darwin and wallace and 1909 saw a greater revolu-tion in biology, speculative and practical, than any period so relatively brief had ever seen.
in the year 1880 the “coming of age” of the origin of species was celebrated. on the 9th of april at the royal institu-tion an address was given by the powerful friend, champion and candid critic of darwin, and before the scientific and educated world huxley was able to say with his own force and directness: “evolution is no longer an hypothesis, but an historical fact.” it may be noted in passing that darwin’s theory of natural selection is not referred to in the address. challenges and opposi-tion from various quarters met this confident claim of the formidable speaker, as doubtless he desired, but the work of the succeeding half-century has done little or nothing that does not establish that claim. it is hardly to be doubted that if in the jubilee-year, 1909, huxley had been alive on this earth, instead of elsewhere, his eloquent voice would have been heard to declare with emphasis equal to that of 1880: “selection is no longer an hypothesis, but an historical fact.” some such statement, with the imprimatur of a great name would have removed from the jubilee-volume that slight aspect as of a dutch chorus3 which is apparent in it. a remark of kelvi
n’s when he was conferring a medal of the royal society on huxley may illustrate what has been said above. he said that they must all be thankful to have still among them that champion of evolution who once bore down its enemies, but was now possibly needed to save it from its friends. it may be regretted that it was not so in 1909.
considering the mole-like and persistent work of the biometricians, some who are at present keeping well-ordered lawns may find some day a few disturbing heaps of facts. i am reminded here of an historic duel, oxford v. cambridge, which took place soon after the introduc-tion of mendel’s discoveries into england at the london zoological society, when prof. bateson expounded them with enthusiasm and when weldon repelled them with cogent and incisive arguments. the duel lasted nearly two hours and that was not too long for the audience, but one has the impression that some of what professor thomson calls muddleheadedness must have been somewhere existing. however, the duel was fought when mendelism was young.
three blows to darwin.
but other historic events are more relevant to my immediate purpose than these.
three blows were delivered against darwinism in the years 1894, 1895 and 1899 by prof. bateson, weismann, and again prof. bateson, under which it seemed to reel, but from which it is more than likely it has derived but greater strength.
bateson.
in 1894 prof. bateson published his large and important work, materials for the study of variation. as a distinguished student and teacher of biology he found the received doctrine of evolution in straits as regards the factor of natural selection in producing specific differences, as indeed happened to another equally eminent man during the next year. he was profoundly discontented as to the origin of specific differences on the theory of direct utility of variations, and he said “on our present knowledge the matter is talked out.”4 he threw over the study of adapta-tion “as a means of directly solving the problem of species.” he came to the conclusion “variation is evolution,” and affirmed that the readiest way of solving the problem of evolution is to study the facts of variation. hence arose this notable book, and hence one of his trenchant statements to the effect “that the existence of new forms having from their beginning more or less of the kind of perfec-tion that we associate with normality, is a fact that once and for all disposes of the attempt to interpret all perfec-tion and definiteness of form as the work of selection,”5 and “inquiry into the causes of variation is as yet, in my judgment, premature.”6 it will hardly be denied that a work which contained such statements as these from such a source seemed momentous in its influence on the fate of darwin’s theory. prof. bateson yielded to none in his loyalty to darwin, as far as he knew himself, and here he is as candid as huxley, and he declares that in his treatment of the phenomena of variation is found nothing which is in any way opposed to darwin’s theory. the shade of darwin might nevertheless have looked with some misgiving at this man over against him with a drawn sword in his hand, and have asked gently, “art thou for us or for our adversaries?” prof. bateson’s work chiefly requires to be considered here because to any reader of it there must come the convic-tion on the one hand of prof. bateson’s merits and power, and on the other of his limita-tion as a student of organic evolution. in 1894 is evident already an exclusive attention to structure rather than function, to anatomy than physiology; the anatomical leaven in doctrine has leavened the whole lump. for him physiology of animals and plants does not exist, or at the best is the outcome of structures which arise through variation and selection. this, if i may say so, is as much his strength as his weakness. there have been other great biologists, such as geoffrey saint-
hilaire and richard owen, of whom this is true. if that were all one would not wish the reader to be troubled with any criticism of one’s betters, indeed such remarks as are here made do not amount to criticism at all, but just plain text-book statements. it is also evident that the outlook of prof. bateson was being prepared for a revela-tion which had not yet come, in which he took a prominent, if not dominant part, i mean the great rediscovery of mendel’s work by de vries, correns and tschermak and himself in england. his keen and close attention to anatomical structures was preparing his mind for the germinal conceptions of unit-characters, dominance and segrega-tion. the intensive cultiva-tion of the fertile field of genetics proceeded apace, and prof. bateson in his contribu-tion to the jubilee-volume of 1909 betrayed the trend of his devotion to a system of distribu-tion rather than formation of the qualities of an organism. the organism as an historical functioning, striving being, had receded once for all from his vision. he hazarded the sugges-tion in heredity and variation in modern lights that “variation consists largely in the unpacking and repacking of an original complexity,” and that “it is not so certain as we might like to think that the order of these events is not predetermined.” incidentally one may remark that, malgré lui, prof. bateson stands forth as a modern paley as does weismann in his great rival and opposing scheme. it is true that he says “i see no ground whatever for holding such a view, but in fairness the possibility should not be forgotten and in the light of modern research it scarcely looks so absurdly improbable as before.” having drawn the sword he threw away the scabbard in 1914 when he occupied the presidential chair of the british associa-tion of science at melbourne and sydney. he had said in 1894 in his book on variation as stated before, “inquiry into the causes of variation is as yet, in my opinion, premature,” and then in 1914 at melbourne, after twenty more years of study of the subject in the mendelian direction, “it is likely that the occurrence of these variations is wholly irregular, and as to their causation we are absolutely without surmise or even plausible specula-tion.” (my italics).7 so, on this fundamental point, he stands where he did when he began the study of variation, but apart from this point he again threw out his sugges-tion of 1909 as to the unpacking and repacking of an original complexity. at melbourne he said, “lotsy has lately with great courage suggested to us that all variation may be due to such crossing. i do not disguise my sympathy with this effort.”8 all variation! he said later, “in spite of seeming per
versity, therefore, we have to admit that there is no evolutionary change which in the present state of our knowledge we can positively declare not due to loss.”9 (italics mine.) these two statements of 1914 are enough to show that the biologist of 1894, 1899, 1909 and 1914 has evolved in a definite line, and it is to his honour that he has remembered “to thine ownself be true.” but he is not so true to himself in his scorn of those who propound theories. for myself i would give little for the biologist who did not hold or propound some theory. what was the penultimate and stirring message of the gifted g. b. howes? “we live by ideas, we advance by a knowledge of the facts.” the self-denying ordinance affirmed and reaffirmed by prof. bateson is not observed even in the melbourne and sydney addresses. in the former, he says “at first it may seem rank absurdity to suppose that the primordial form or forms of protoplasm could have contained complexity enough to produce the divers types of life,” and asks us to open our minds to this possibility. again “i have confidence that the artistic gifts of mankind will prove to be due not to something added to the makeup of an ordinary man, but to the absence of factors which in the normal person inhibit the development of these gifts.” and at sydney, “ages before written history began, in some unknown place, plants, or more likely a plant of wheat lost the dominant factor to which this brittleness is due, and the recessive thrashable wheat resulted. some man noticed this wonderful novelty, and it has been disseminated over the earth. the original variation may well have occurred once only in a single germ,” and “so must it have been with man.”10
these are three stupendous stretches of imagina-tion and theory in one address, which would have been the poorer if they had not overcome the accomplished speaker’s dislike of the theories—of others. if they are not ideal constructions of a high order i do not know the meaning of that term. they are worthy of weismann the prince of ideal constructionists. prof. bateson might indeed be another newton with his hypotheses non fingo.
turning to another important biological doctrine one can see what it may be legitimate to call a bi-phyletic parallelism in the biological make-up of prof. bateson. again is seen consistency of view and loyalty to his first love. two references from these addresses will be enough to introduce the point.
at melbourne, “we thus reach the essential principle that an organism cannot pass on to offspring a factor which it did not itself receive in fertiliza-tion.”11
at sydney, “the factors which the individual receives from his parents, and no others, are those which he can transmit to his offspring”12—in other words the doctrine of the inheritance of acquired characters is estopped. as to this he speaks in 1909 more doubtfully on p. 90 and on p. 95 almost dogmatically.13 there is just a convenient haziness of meaning in the term “factor” with which some play might be made, but, taking it to mean what the context indicates, an acquirement made by the individual during its personal life, we have pretty clear evidence that prof. bateson will have nothing to do with the inheritance of acquired characters as that doctrine is understood by the unsophisticated biologist. this opposi-tion should be counted unto him for righteousness rather than the reverse, for it falls into line with his life’s work to which he has given of his best.—vestigia nulla retrorsum. the point reached here which concerns my purpose is that the orthodox mendelian still knows nothing of the cause or origin of variation, and will have none of lamarck.
this considera-tion of prof. bateson’s work of a quarter of a century has been necessary for showing how the work of weismann and himself diverge gravely and yet meet at one point, and the year 1899, being linked with 1894, has been taken out of its chronological order.
it may be permitted perhaps to say respectfully to the mendelians in the words of the dying father in the fable, “dig, my sons, dig in the vineyard.” if they follow still the course of the sons they may find more gold than they have found already and perchance that which is better than gold. but they will produce from it nothing that is not there.
two parables.
here gentle reader (i seem to remember this style of address in the stories of our youth) pause with me in a little oasis of the desert-stage of our journey, and brush off some of the dust, while i briefly narrate two incidents, but i pray you also not to leave me in the midst of them so that you may escape the next short stage.
a traveller, small and insignificant, armed only with an oak cudgel, was passing alone through a south american forest. as he trudged forward he noticed at a certain point in the path (shall we call it 1894–1899?) that a jaguar was watching him and was about to break his truce with man. he turned off to the right and there he saw a puma and this too
seemed to meditate evil. he hastened forward just in time as his two enemies sprang at him, and these two near relatives were locked in mortal grip—and so he passed on safe!
the reader, naturalist or layman, can point the moral for himself.
at the battle of trafalgar, while fighting was in full progress on one of the ships, some sailors were occupied in throwing overboard the bodies of those who had been killed. a poor scotchman badly wounded and hardly conscious was taken up by two seamen, an englishman and an irishman, and as they were about to throw him overboard his feeble voice was heard to say “i’m no deed yet.” “what’s that?” said the irishman. “i’m no deed yet”; “arrah, the doctor said he was dead, over wid him,” said the irishman.
weismann.
during the period 1894–1899 there was a dramatic proclama-tion on the part of one of the greatest living biologists, which was, in the cosmos of biology, what the proclama-tion of the empress-queen of india was in 1876, and it is not out of place to remind the reader that the fates of the two imperial utterances have been somewhat different. in 1895 weismann issued his official statement of doctrine which was to crown the work of his life, an essay on germinal selection. from freyburg in november, 1895, he wrote a preface to his address delivered on september 16th in that year to the international congress of zoologists at leyden. this formed an epoch in biological thought and there lived none so well qualified as weismann to stand forth as its interpreter. the well-translated, forcible language, and lucid thought leave the reader in no manner of doubt as to his meaning. it took a wider form in his final book on the evolution theory, but the germinal and essential thoughts of the latter were contained in the former. from 1895 onwards the praise of weismann was in all the churches. probably no modern worker in the fields of heredity and evolution has done so much as weismann towards raising great issues and removing some ancient misconceptions; but it is one thing to raise great issues and another to solve them. in this he has signally failed, nevertheless biological theory would be the poorer if he had not made the attempt. reflec-tion, the work of other biologists, and the remorseless hand of time have shaken the edifices then raised. i will here only bring forward a few of the most illuminating passages of the 1895 essay, and then refer to the handling of weismann’s work by romanes.
this trenchant essay contains fifty-seven pages, of which reasoning forms the greater part. as to the facts it might well pass for an essay from professor poulton’s pen, for weismann’s special province of insects occupies nearly all the evidence from facts. outside this highly specialised group there are exactly fifty-three lines, or one and a half pages, which deal with other animal groups, and there are four casual allusions to plants occupying twelve lines in all! in the essay of 1909 on the selection theory this treatment of animated life in the world is improved upon and thirteen out of its forty-seven pages refer to animals outside his favourite group of insects. such exclusive dealing with these little things does not commend the reasoning, at any rate to a neo-lamarckian; such a circle is too select for him.
weismann’s twelve points.
the most striking remarks from the 1895 essay on germinal selection are:—
1. “the real aim of the present essay is to rehabilitate the principle of selection. if i should succeed in reinstating this principle in its imperilled rights, it would be a source of extreme satisfac-tion to me.”14
2. speaking of the whole theory of selection he claimed to have found a position “which is necessary to protect it against the many doubts which gathered around it on all sides like so many lowering thunder-clouds.”15 and he speaks on page 26 of “the flood of objections against the theory of selection touching its inability to modify many parts at once.”
thus weismann stood forth to defend the crumbling edifice of darwinism and threw his shining sword into the scales, a scientific athanasius “contending for our all.” again is seen a friend of darwin from another camp than that of mendel, whose support needs to be received with some caution. toujours en vedette is a useful rule.
3. speaking of adaptedness in animated nature he says, “we know of only one natural principle of explana-tion for this fact—that of selection.”16
4. “germinal selection is the last consequence of the applica-tion of the principle of malthus to living nature.”17
5. “without doubt the theory (germinal selection) requires that the initial steps of a variation should also have selective value.”18
6. “something is still wanting in the theory of darwin and wallace which it is obligatory on us to discover if we possibly can. we must seek to discover why it happens that useful variations are always present.”19
7. “it is impossible to do without the assump-tion that the useful variations are always present, or that they always exist in a sufficiently large number of individuals for the selective process.”20
8. “some profound connexions must exist between the utility of a variation and its actual appearance, or the direction of the variation of a part must be determined by utility.”21
9. that “germinal selection performs the same services for the understanding of observed transformations . . . that a heredity of acquired characters would perform without rendering necessary so violent an assump-tion!”22 (italics mine.)
10. weismann speaks warmly of professor lloyd morgan for his caution and calmness of judgment but complains of him that he “has not been able to abandon completely the heredity of acquired characters.”23
11. as to passive effects of environment, etc., he says “the lamarckian principle is here excluded ab initio.”24
12. “it seems to me that a hypothesis of this kind (lamarckism) has performed its services and must be discarded the moment it is found to be at hopeless variance with the facts.”25
i have only to add here that several years ago i wrote to weismann drawing his attention to some facts i had observed which seemed to me to be instances of use-inheritance, and i received a reply in polite but brief and prussian terms to the effect that the facts referred to must be capable of some other interpreta-tion, for the machinery for their transmission did not exist.
each of these twelve quotations from weismann’s essay is important from the present point of view, and shows how far neo-darwinians are likely to promote the greater glory of darwin, and though more than a quarter of a century elapsed between this essay and his death weismann was not the man to have repudiated any of these strong statements.
lighthouse value.
i hope at this point a small digression is not out of place in order to introduce an aspect of weismann’s work which is not usually appreciated. a child is aware of the great and lesser lights that rule the day and night, but for modern man these are not
sufficient. accordingly he has invented from immemorial times his oil lamps, rushlights, tallow and wax candles, gas and electric light for the illumina-tion of his streets and houses. prehistoric man did not seem to need them, as he thought. these useful examples of applied knowledge were obviously brought into use for showing man better where he was going and where to go, what he was doing and what he wished to see. i hope this trite remark may be pardoned, for there is another form of light which suits my purpose of illustrating the aspect of weismannism referred to above, that is the light of a lighthouse. the ancients in their crude way saw the need for this and as far back as the days of ptolemy ii. a tower to give light was erected on the island of pharus, off the egyptian coast, and it was called a pharos. man found it necessary, as naviga-tion and seafaring advanced, to use this principle more and more, and on headland, sandbank and rugged coast has built noble structures to aid the sailor in his dangerous course. the oldest and finest of these in great britain is the eddystone lighthouse, built first in 1695 by winstanley and finally by smeaton in 1756–9. for what reason is a lighthouse built and placed where it is? for the precisely opposite reason to that of the domestic candle. while this shows you where to go and how better to do your immediate business, a lighthouse is for the main purpose of showing a mariner where he should not go. it has no relation to adornment or pleasure. it does not invite you to come in your vessel and admire it. it tells you to go away and avoid the sunken rock or treacherous sands.
i submit here the sugges-tion with all deference, that the final work of weismann has lighthouse value of a high order, as to the modus operandi of evolution. his greatness as a biologist, his candour and skill in dialectics, have built up a veritable lighthouse which may usefully warn the seeker after the path of evolution that he must turn elsewhere if he would not founder upon a reef of facts.
the two great contributions to evolutionary thought that weismann has made should be considered separately, the theory of germ-plasm and that of evolution, though the latter seems to be the necessary outcome of the former. but the truth of weismann’s view of heredity does not of necessity require the error of his theory of evolution.
romanes on weismann.
for this study the examina-tion of weismannism by romanes published in 1893 is of great value. i need only refer here to the main conclusions of that lucid and learned examina-tion.
weismann’s work on the germ-plasm in pursuance of a theory of heredity is pronounced by romanes to have remained up to 1893 substantially unaltered, though largely added to in matters of detail, and at the present time as far as i gather from a study of the more recent literature this theory holds the field or at least a commanding position in it.26 originally he held that the germ-plasm possessed perpetual continuity since the first origin of life, and absolute stability since the first origin of sexual propaga-tion, but he has shown himself willing to surrender the first postulate, and has himself altered the second. as it stands now it must be admitted that the continuity of the germ-plasm is an interrupted continuity with the appearance of every inherited change; the continuity is theoretical, not actual, and the stability of the germ-plasm is not absolute but of a high degree. we can thus see in the story of this original theory of heredity the lighthouse value of the pharos of ptolemy ii.
it is far otherwise with weismann’s theory of evolution. romanes shows that with the removal of its essential postulate the absolute stability of germ-plasm, weismann’s theory of evolution falls to the ground. he has indeed surrendered much in his later building, his second temple of solomon, and prominent among these was the claim that the only causes of individual variation
and of the origin of species in the uni-cellular organisms are the lamarckian factors, just as in the multicellular the only cause of these is natural selection. thus we see standing at the critical date, 1892, the first eddystone lighthouse of winstanley, a greater and more important structure than the old pharos.
germinal selection.
it can hardly be doubted that one of the “thunderclouds” threatening darwinism, of which weismann spoke in 1895, was this examina-tion of weismannism by romanes. as the case stood then some fresh strategy was needed if victory for darwin was to be won, at least so the great leader said. it must be remembered that it was the personal selection of darwin which was held to be in danger. accordingly germinal selection was brought forth and remained the basis of weismann’s later evolution theory of 1904 and 1909. romanes did not live to see or assist in the disproof of this ambitious piece of work so that his “examina-tion” is so far incomplete.
the position of germinal selection is defined in weismann’s statement that “it is the adaptive requirement itself that produces the useful direction of variation by means of selectional processes within the germ.” here it is in a nutshell. the theory itself is consistent, and clearness has been added to the earlier evolution theory by the claim that a struggle for nutriment occurs within the fertilised ovum between the innumerable determinants of the different parts, so that maintenance or victory over weaker determinants takes place. thus we have a survival of the fittest in petto in the germ analogous to that of the individual organisms as we see them. there is of course a resemblance here to the cellular or histonal selection of roux, but his doctrines are not weighted with the intolerable dogma of the non-inheritance of acquired characters. but ultimately this concep-tion of germinal selection has to come down and bow to the tribunal of facts, and the remark of weismann on lamarckism which has been already quoted, “it seems to me that an hypothesis of this kind has performed its service and must be discarded the moment it is found to be at hopeless variance with the facts,” confronts the consistent weismannian. and i venture to say here that germinal selection is represented by the eddystone lighthouse of 1756–9 erected by smeaton.
the grounds for this statement are afforded by numerous facts and experiments, to which in the later chapters i propose to add a few fresh ones, and by a growing body of opinion and authority in favour of lamarckian factors in evolution.
three “lighthouses” of this metaphorical sort have thus been afforded by the work of weismann, represented by the pharos of old, winstanley’s eddystone lighthouse and that of smeaton.
authority.
we have then weismann and professor bateson definitely ranged against the position taken in this volume as to a cause or origin or variation and the inheritance of acquired characters. to these we must add the great weight of sir e. ray lankester’s opinion lately given in a reply to professor adami that “it is very widely admitted (more correctly “claimed”) that no case of the transmission of what are called acquired characters from parent to offspring has been demonstrated in so far as those higher animals and plants which multiply by means of specialised egg-cells and sperm-cells are concerned.”
it is not necessary to mention more than these “three mighties” of the biological world.
many others such as prof. j. arthur thomson and prof. w. k. brooks, of johns hopkins university, are still unconvinced as to lamarckian factors and ask for more evidence, and they have many to support them in their opinion and claim. there is often a tone of weariness, as well as wariness in their remarks on the matter.
in favour of the neo-lamarckian position, with which stands or falls the suggested cause of variation, there is a growing body of opinion, with the mention of which i conclude this review.
1. the accomplished writer of form and function, mr. e. s. russell, says the theory of lamarck “although it had little influence upon biological thought during and for a long time after the lifetime of its author, is still at the present day a living and developing doctrine.”27
2. sir francis darwin from the presidential chair of the british associa-tion of science in dublin in 1908 proclaimed his adherence to the mnemonic theory of heredity, foreshadowed by samuel butler and inaugurated by semon, a condition of which is that acquired characters are inherited. this caused much stir in the camp of “our friends the enemy.”
3. observations and experiments at variance with germinal selection and its negative presupposi-tion have been rapidly accumulated from the work of botanists and zoologists who were prepared to appeal to the tribunal of natural processes; though weismann and some of his followers, with some reason, look upon the evidence from plants as a weak link in the chain of evidence.
many of the observations and experiments are well-known and only a mere mention of them need be made here, they are such as mr. j. t. cunningham’s observations on the effect of light on the under surface of flounders, kammerer’s on the changes in the colour of salamanders to surrounding objects, and others by him on certain amphibia and reptiles especially alytes held by professor mcbride to be convincing, though the latter are to be repeated at the london zoological society’s gardens and are therefore sub judice—others on brine-shrimps, on the effects of change of food on bee-grubs and tadpoles, and of the change of level of environments of certain cereals—others by henslow on plants which have never been refuted, and many by the late prince kropotkin. the latter have appeared at length in certain issues of the nineteenth century in september 1901, march 1912, october 1914, and the last in january 1919, and they deal both with plants and animals, and are too numerous to be mentioned here individually.
again, professor dendy as president of the zoological section of the british associa-tion of science in september, 1914, devoted most of his address to the subject of lamarckism and firmly claimed as a necessary factor of evolution “the direct response of the organism to environmental stimuli at all stages of development, whereby individual adapta-tion is secured, and this individual adapta-tion must arise again and again in each succeeding genera-tion.” he also maintains this position in several passages in his important work outlines of evolutionary biology published in 1912.
a statement by professor bower, president of the botanical section of the british associa-tion of science in 1914 should also be noted: “i share it (the doctrine in question) in whole or in part with many botanists, with men who have lived their lives in the atmosphere of observa-tion and experiment found in large botanical gardens and not least with a former president of the british associa-tion, viz., sir francis darwin.”
professor adami, in 1917, published an original work called medical contributions to the study of evolution in which from his extensive knowledge of the subject he deals with evidence of inheritance of acquired characters in lowly organisms as well as higher animals from the point of view of pathology.
enough has been stated here to show that the dogma of weismann or lamarckian factors in organic evolution, qua authority, has been in poor case during recent years, and it remains for me now to add my small quota of the authority of facts.