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and their proper place in the scheme of natural selection within somewhat of nature, the light that was shed by narrow boundaries. With Wallace, on the new theory upon the subsidiary the other hand, natural selection has departments of embryology, palæontol been from the first the all-important ogy, and distribution, the stimulus that factor. was given to every branch of biological The position of Darwin himself reinquiry, all contributed to make the quires to be examined with some care. epoch a memorable one in the history This is a subject on which misappreof science, and to raise the conception hension and misstatement are rife. It of organic evolution to a position in- is perfectly justifiable to distinguish, finitely more important in the realm of as Huxley did, between the central thought than it had ever occupied be- theory of evolution and the particular fore. The doctrine had never been left views as to its methods and causes quite without a witness, but its sup- which were adopted by Darwin. Moreporters had for long become a mere over it is most certainly the case that remnant. Lamarck had failed to in- the really essential part of Darwin's fluence his contemporaries; Buffon presentment of the theory of evolution could not even convince himself. But was the use that he made of the prinwith the appearance of the Origin of ciple of natural selection. This is Species the scene was changed. Hux- rightly ixed upon as the distinctive ley, Hooker, and Asa Gray, soon fol- feature of his teaching. But it is not loved by Lyell, boldly ranged them- true to say, on the one hand, that the selves on the side of Darwin, and the only factor in evolution admitted by voc clamantis in deserto was speedily Darwin was natural selection, nor, on taken up by the combined shout of a the other hand, is it allowable to claim great army.
Darwin as a kind of disciple of LaAt this point it is important to note marck. Darwin's attitude towards the that, undeniable as was the effect of various factors suggested by Lamarck Darwin's work in procuring acceptance and Buffon, and his final estimate of for the theory of evolution, first among their importance in relation to natural men of science, and then among the selection, have been so clearly stated cultivated public at large, the converts by himself that it is surprising that that it made did not always adopt the any doubt on the matter should ever actual Darwinian standpoint, Huxley, have arisen. As, however, his views on for example, though welcoming the these points are still often misstated suggestion of natural selection with the by speakers and writers whose words characteristic remark, “How extremely command respect, it may not be out stupid not to have thought of that!" of place once more to print his own and though constantly keeping it in emphatic declaration as given in the view as the best if not the only work- sixth edition of the Origin. ing hypothesis available, yet preserved
“I have now recapitulated,” he says, to the end a certain scepticism as to its
“the facts and considerations which adequacy to perform the results
have thoroughly convinced me that claimed on its behalf. He was rather species have been modified, during a converted by than to natural selection, long course of descent. This has been and the same was no doubt true of effected chiefly through the natural
selection of numerous successive, many others. Herbert Spencer, though
slight, favorable variations; aided in already a supporter of evolution before
an important manner by the inherited the appearance of the Origin, has al
effects of the use and disuse of parts; 'ways been inclined to limit the action
and in an unimportant manner, that is
in relation to adaptive structures, teaching agreeable to their views, there whether past or present, by the direct was little or no disposition to dispute action of external conditions, and by his claim to the first place among expovariations which seem to us in our
nents of the doctrine of development. ignorance to arise spontaneously. It
But during the last twenty years the appears that I formerly underrated the frequency and value of these lat- case has altered. The apple of discord ter forms of variation, as leading to has been thrown into the midst of the permanent modifications of structure evolutionists' array, with the result of independently of natural selection.
causing them to draw apart into two But as my conclusions bave lately
hostile camps, between which at presbeen much poisrepresented, and it has
ent there seems small prospect of a been stated that I attribute the modi.
reconciliation. fication of species exclusively to nat
The first name to be ural selection, I may be permitted to
generally associated with the new evoremark that in the first edition of this lutionary movement was that of Prowork, and subsequently, I placed in a fessor Weismann, to whose share in most conspicuous position-namely,
the controversy we now propose to deat the close of the Introduction-the
vote some attention. following words: 'I am convinced that
It will be evident to anyone who has patural selection has been the main 8 but not the exclusive means of modi.
appreciated the nature of the “La. fication.'
marckian factors" that they necessar
ily include the hereditary transmission From this and other passages it is of characters acquired by the individabundantly clear that in Darwin there
ual. If the effects of use and disuse met two distinct lines of evolutionary are confined to a single generation, it theory. The words just quoted.contain is plain that they cannot be invoked an explicit recognition of Lamarck's as the agents of progressive modificaand of Buffon's factors as auxiliaries tion. It is only if the whole or at least to Darwin's own factor of natural se- a part of what has thus been gained by lection. The first (the inherited effects the individual is handed on to the offof use and disuse) is spoken of as im- spring that the changes produced in portant, the second (the direct action of that individual will take any share in external conditions) as unimportant, the development of the race. That but each is admitted as a vera causa. this self-evident truth was never looked So far as Darwin was concerned, bis upon as an objection to the views of own great illuminating principle of Buffon and Lamarck was due to the natural selection supplied what was remarkable fact that scarcely anyone wanting in the Lamarckian system, but had thought of questioning the power did not entirely supersede it. There was of heredity to transmit in a greater or room for Buffon's "direct action of the less degree the characters that are environment," and for Lamarck's "use known as “somatogentic,” or, as Lloyd and disuse of parts,” by the side of Morgan expresses it, “modifications due Darwin's "natural selection.”
to individual plasticity.” When, thereSo matters rested for a time, and as fore, Weismann put forward his theory most believers in evolution, whether of the “continuity of the germ-plasm," they were inclined to estimate natural which involved a denial of the hered. selection at a high or at a low rate, itary transmission of somatogenetic found at least some part of Darwin's characters, it had the effect of a bolt
from the blue. It is true that similar 11o the sixth edition the words of the Intro
views had been advanced nearly sixty duction are, "the most important, but not the exclusive means of modification."
years earlier by the great pioneer of
ons which I me that , during : his has been the natural
succesire 78; aided in the inheritai -lise of parts: abuer, that is
anthropology James Cowles Prichard, ing evolutionists, among whom it may and also by Francis Galton in 1872, but be sufficient to specify Professors Poulit was reserved for Weismann to com- ton, Lloyd Morgan, Karl Pearson, Mel. pel universal interest in the question, dola, Spengel, and Cossar Ewart, toand to bring home to the defenders of gether with thoughtful writers like Mr. the validity of the Lamarckian factors Headley (the author of Problems of the necessity of proving their funda- Evolution) and the veteran Alfred Rusmental tenet of the transmission of ac- sel Wallace. quired as distinct from congenital (or The validity of natural selection Inborn) characters. So much had this stands, of course, entirely outside the power of transmission been taken for present controversy, for the existence granted, that it was difficult at first to of the individual variations which form convince many of its upholders that the material for the selective process there was anything to argue about. In is an absolutely indisputable fact. time, however, the wide difference with Whether the diverse characters shown respect to heredity between "somato- by these variations are “congenital," genetic" and "blastogenetic” charac- "centrifugal," "blastogenetic" on the ters, i.e. between those imprinted on one hand, or "acquired,” “centripetal," the body and those which take their "somatogenetic" on the other, makes origin from the germ, began to be gen. no difference to the selective process, erally recognized; and it was seen that which, if it acts at all, must act inditthe inheritance of the former in any ferently on all the material presented degree, whether great or small, could to it, however that material may have not be regarded as an axiom. The bur- originated. What is really at stake, den of proof, therefore, was naturally therefore, in the issue between the considered to devolve upon those evo supporters and the impugners of the lutionists who, like Herbert Spencer “transmission of acquired characters" in this country and many others both
is the claim to consideration of in Europe and America, still main- the factors alleged
Lamarck tained the species-forming capability of and Buffon; not
the Darwinian the Lamarckian factors to the partial, principle of natural selection, which if not complete, exclusion of natural in the logical sense is entirely selection. The challenge has been tak- compatible with either view. Darwin en up with vigor, and many attempts himself, as we have seen, accepted at the required proof have been made; Lamarckism as an auxiliary; the posibut it cannot with truth be alleged that tion of Romanes was not greatly disthe Lamarckian view of the hereditary similar; and at the present day Plate transmission of acquired characters in Germany argues stoutly in favor rests as yet on a firm basis of either both of the potency of natural selection observation or experiment. All the and of the transmission of characters facts hitherto brought forward in its individually acquired. Nevertheless support have proved capable of ex- there can be no doubt that, in spite of planation on other lines; while the the efforts of “reconcilers" like Plate, a priori difficulties in its way are, there is now becoming visible a wellon physiological grounds, very great. marked cleavage in the ranks of evoThere is, of course, no warrant for ab- lutionists. The challenge thrown down solutely denying the possibility of such by Weismann has had the effect of a phenomenon, but that little or noth- making the adherents of the Darwinian ing has yet been done to establish it principle of natural selection reconsider as a fact is the opinion of many lead- their position with regard to the La
marcklan factors. To many, if not to en up natural selection. On the other most of them, it has seemed that as hand Romanes assures us from private natural selection is under no logical knowledge that the question of the necessity for calling those factors to its transmissibility of acquired characters aid, and as an indispensable link in the was constantly before Darwin's mind chain of evidence in their favor is still during the last few years of his life, wanting, it is best to ignore them al- and that he deliberately refused to together, and to explain the course of renounce his belief in it. Nevertheless, organic evolution entirely on the basis when we consider the position now ocof natural selection. To evolutionists cupied by those biologists who have of this school the name “Neo-Darwin- always been most in sympathy with jan” is commonly applied-not without
Darwin's own views and methods, protest from their opponents, who point there seems to be fair ground for the with justice to the fact that Darwin conjecture that Darwin himself would never denied the efficiency of the eventually have been affected by the Lamarckian factors, and finally came same scepticism with regard to the to regard them with greater favor than fundamental Lamarckian tenet. That at fişst. Still, inasmuch as the whole he would have maintained the exact of Darwin's work was done under the position indicated by the last edition inspiration of the principle of natural of the Origin of Species is hard to beselection, as witness the full title of the lieve. Origin, and inasmuch as it is the adop- The foregoing will have made clear tion of this principle that constitutes what is meant by those who affirm that the distinctive feature of his contribu- "Weismann is more Darwinian than tion to evolutionary theory, the im.
Darwin himself.” Weismann follows mense importance and far-reaching in
Darwin in adopting the principle of fuence of which contribution none will
natural selection; he out-Darwins Dardispute, we think the school we have win in sweeping all relics of Lamarckmentioned quite justified in continuing ism out of his system, and in carrying to rank themselves under the name of
the doctrine of selection into regions the great English evolutionist. The which Darwin left unexplored. But aldisposition to reject the Darwinjan though from this point of view Weiscompromise is also seen in the forma- mann may be fairly described as an extion of the hostile party of “Neo
treme Darwinian, there is another asLamarcklans," who, undeterred by the pect of the matter in which, paradoxiserious flaw in their case which has cal as it may seem, he and Darwin are been already pointed out, are becoming at opposite poles. To this we shall be more and more inclined to rely upon brought by returning for a moment to supposed “laws of growth,” “orthogen
Weismann's famous theory of heredity, esis," use inheritance, and the trans- which may be summed up in brief as mission of the direct effects of the the "continuity of the germ-plasm.” environment; to the minimizing or even
It is important that a clear distinc. the complete exclusion of natural se
tion should be drawn between this lection. It is, of course, impossible to
latter question and that of the alleged say what line Darwin would himselt transmission of acquired characters. have taken in view of the present as
The continuity of the germ-plasm, or pect of the controversy. We may, how reproductive material, from generaever, fairly regard it as inconceivable,
tion to generation, the bodies of sucor at least in the highest degree im
cessive individuals being regarded probable, that he would ever have give merely as buds from a perennial
stock, is a theory devised to account theory of the continuity of the germ. for the observed facts of inheritance, plasm, does not necessarily stand or and with our present means of re- fall with that theory. The common search is hardly capable of direct failure to distinguish between the two verification. The
probandi of positions is answerable for a great such a theory undoubtedly rests with deal of isunderstanding which might its propounder. The transmission of easily have been avoided. It may be acquired characters, on the other suspected that another source of mis. hand, is not so much a theory as a apprehension is to be found in Darsimple question of fact. Does it hap- win's use of the term “pangenesis."? pen or does it not? Here it would To many people who get their ideas seem that those who affirm that it does on these subjects at secondhand, the happen are bound to show when expression “theory of pangenesis" simit occurs and where. Those who deny ply conveys the notion of a belief in it, like Weismann, are simply appeal- the descent of all forms of life from a ing to the universal experience of common stock. When, therefore, they mankind. The Chinese infant at birth hear it stated that the ultra-Darwinhas well-formed feet; nor is a young ian Weismann's view of descent is fox-terrier born with its ears and tail diametrically opposed to Darwin's ready cropped. But instead of produc- theory of pangenesis, they are nating their evidence, the Neo-Lamarck- urally puzzled. The fact is that “panians now seem inclined to rely on the genesis" has nothing to do with often-repeated assertion that "Weis
action of natural selection. mann has not proved his point.” It The term is merely used by Darmay be perfectly true that he has not win to express his conception of the proved his theory of the germ-plasm, relation of the reproductive material the verification of which in any case to the parent organism. According to must needs be a most difficult under- Weismann, individuals are not manutaking; but these critics are apt to for- facturers but only nourishers and carget that the transmission of acquired riers of the germ-plasm. This germcharacters, though it would fall of it- plasm they have received from their self if Weismann could prove not ancestors; in due time they produce only the continuity but also the sta- descendants, bility of the germ-plasm, is not established by his failure to do so. The
Et quasi cursores vitai lampada tra
dunt. transmission doctrine must either be proved by its supporters or must be In Darwin's view of the process of allowed to go by default. The univer- heredity the germ-plasm of the indi. sal negative of Weismann could be vidual is not derived directly as such met by a particular affirmative. Why from the germ-plasm of the parent, is the latter not forthcoming? The but is constituted and reinforced by scientific world still waits for a single contributions from every part of the unequivocal instance of a character body of the individual itself: whence acquired by an organism in virtue of the term pangenesis. According to its individual plasticity, and passed on Weismann the germ makes the body; by inheritance to a succeeding genera- according to Darwin the body makes tion.
the germ. The opposition between We see, then, that Weismann's' de- these two views, which are sometimes nial of the inheritance of acquired spoken of respectively as “centrifu. characters, though connected with his gal” and “centripetal," is obvious, as