512 



NATURE 



\April 3, i8go 



Can it be that Prof. Lankester has not even yet perceived the 

 significance of "the idea" of panmixia? Such certainly seems 

 to be the case from his use of the above quotations. For the 

 words which I have italicized render it most obvious that the 

 only principle under consideration is the economy of growth or 

 nutrition, i.e. the reversal oi selection: there is no allusion to 

 panmixia, or the cessation of selection. In the second passage 

 it is shown that, because " no longer checked by natural selec- 

 tion," useless organs will become variable ; and hence that if 

 there were any other cause tending to degeneration (such as the 

 "impoverished conditions" subsequently suggested), natural 

 selection would not interfere vi'iih — /.^.prevent or "check" — 

 the degenerating process thus induced. But there is no hint 

 that the mere cessation of natural selection must be itself, and in 

 all cases, a cause of degeneration. 



Similarly, at the end of his letter, Prof. Lankester again fails 

 to distinguish between the cessation and the reversal of selection. 

 For, after endeavouring to represent that Mr. Darwin did not 

 understand my "view,"-' he says, " it is not at all surprising that 

 Mr. Darwin did not recognize any resemblance between it and 

 his own statement, viz. that ' the materials forming any part, if 

 not useful to the possessor, are saved as far as possible,' thus 

 'rendering a useless part rudimentary.'" Not surprising, in- 

 deed. But it is surprising that Prof. Lankester, even at this 

 time of day, should thus appear incapable of clearly distinguish- 

 ing between natural selection as withdrawn and as reversed. 

 For this is the whole point, and the only point so far as " the 

 doctrine of panmixia " is concerned. It is a matter of familiar 

 knowledge that Mr. Darwin at all times and through all his 

 works laid considerable stress upon the "economy of growth," 

 (or, more generally, reversed selection) ; but, most emphatically, 

 this is not, as Prof. Lankester now says it is, " the essence of the 

 anti-Lamarckian view of the effects of disuse." The essence of 

 this view is, and can only be, the cessation of selection, as Prof. 

 Weismann has clearly perceived.^ 



In order that there shall be no doubt upon this point, I must 

 here explain the importance of the cessation of selection, as 

 distinguished from the reversal of selection, in regard to "the 

 essence of the anti-Lamarckian view " — even though in so doing 

 "I feel it rather a severe burden when 1 am called upon to 

 expound the merest commonplaces of the subject under dis- 

 cussion." 



As stated in my previous letter, " the principal evidence on 

 which Mr. Darwin relied to prove the inheritance of acquired 

 characters was that which he derived from the apparently in- 

 herited effects of use and disuse — especially as regards the 

 bones oj onr domesticated animals." Now, the reason why our 

 domesticated animals appeared to furnish the most unequivocal 

 proof of the inherited effects of disuse (and so, likewise, of the 

 inherited effects of use, as explained in my last letter) was this. 

 In the case of all species in a state of nature, it is, as Darwin 

 observed, impossible to eliminate the effects of natural selection 

 (acting through the economy of growth, or otherwise) from 

 those of disuse, supposing disuse to be a cause of degeneration 

 in species as it is in individuals. Therefore, in order to 

 estimate what, if any, is the proportional part that is played in 

 degeneration by the inherited effects of disuse, it is necessary to 

 find cases where disuse, if it ever acts at all, must be acting 

 alone. Such cases Mr. Darwin took to be furnished by our 

 domesticated animals, seeing that they are so largely pro- 



' There is something comical to me in this endeavour, in view of all the 

 conversations and correspondence which I had with Mr. Darwin upon the 

 cessation of selection. Moreover, I do not in the least agree with Prof. 

 Lankester where he says that my "view, as it appears in Mr. Darwin's 

 words ('Variation,' &c , vo'. ii. p. 309), is certainly not the same as that 

 which Mr. Romanes has e.xpounded in Nature of March 13. 1890." That 

 my " view" is not. fully given, Mr. Darwin himself affirms ; but, "as far as 

 it can be given in a few Wurds," it is given as correctly as I could wish. 



- It appears to me that Prof. Lankester cannot have read Prof. Weis- 

 niann's expositi m of "the doctrine of panmi.xia." For, not only does he 

 make this otherwise unaccountable (and, in relation to his "anti-Lamarckian 

 view," suicidal) blunder of seeking to unite, if not virlu^lly to identify, the 

 principles of panmixia and economy of growth ; but he alludes to Weismann 

 as having "stated briefly" the former principle. "Stated briefly" it 

 certainly is in "the translated essays " ; but this is only because it is set out 

 at length in one of the untran.slated essays, which is entirely devoted to ex- 

 pounding the matter_(" Ueber den Kiickschritt in der Natur"). And this re- 

 minds me that in his review of Mr. Wallace's " Darwinism " there is a 

 passage which similarly indicates that Prof. Lankester has either not read, 

 or has strangely forgotten, another of Weismann's unpublished essays. 

 Therefore, seeing how ready he is, on account of a precisely sim.lar omission, 

 to jump upon Mr. Herbert Spencer — whose recent and protracted illness is 

 notorious — one can scarcely refra.n from asking in his own words, "Will 

 not Mr. Spencer and others who are interested in these matters read 

 Weismann's essays ? " 



tected from the struggle for existence on the one hand, 

 while, "on the other hand, with highly-fed domesticated 

 animals, there seems to be no economy of growth, nor any 

 tendency to the elimination of superfluous details." Having 

 found in such cases material for ascertainingthe effects apparently 

 caused by disuse alone, Darwin concluded that he was able to 

 estimate the degree in which these effects occurred elsewhere, 

 or generally ; even though in all wild species they must usually 

 be more or less associated with the effects of reversed selection. 

 Therefore it was that he chose domesticated animals for all his 

 weighings and measurings of comparatively disused parts — with 

 the result of appearing to obtain good evidence of a high degree 

 of reduction as due to the inherited effects of disuse alone. 

 But it did not occur to him that the amount of reduction thus 

 proved might be equally well explained, not indeed by the 

 reversal of selection (as in wild species), but by the cessation of 

 selection, or panmixia. And it is just because the cessation of 

 selection thus applies with even more certainty to the ease of 

 domesticated animals, than does the reversal of selection to the 

 ca?e of wild animals, that the former principle is of such unique 

 importance to " the essence of the anii-Lamarckian view " : by 

 its means, afid by its means alone, can the apparent evidence of 

 the inherited effects of disuse be overthrown. 



Therefore, by seeking to assimilate the distinct principles of 

 selection as withdrawn and selection as reversed, Prof. Lankester 

 is performing but a sorry service to his anti-Lamarckian cause. 

 Weismann may well cry, " Save me from my friends," when he 

 finds them thus playing into the hands of his opponents. For 

 on all the logical bearings of his principle of panmixia, Weis- 

 mann has perfectly clear and accurate views ; and although he 

 was not accurate in representing the relations which obtain 

 between this principle and that of reversed selection, such is 

 but a small error compared with Lankester's identification of 

 the two principles — with the necessary result of again bringing 

 into court the whole body of direct evidence on which Darwin 

 relied in his apparent proof of Lamarck's "second law." 



We shall now, perhaps, be able to understand what Prof 

 Lankester means when he says : "The idea [of panmixia] oc- 

 curred to me also shortly after the passages above quoted from 

 Mr. Darwin were published." If this is the case, "the idea" 

 in question must have "occurred" to Prof. Lankester before he 

 had reached his teens, seeing that one of "the passages" in 

 question is not confined to "the last edition of the ' Origin of 

 Species,'" but runs through them all. Allowing this to pass, 

 however, what I have now to remark is, that if the idea which 

 occurred to Prof. Lankester "shortly after the publication of 

 that work " (1872) was, as he alleges, the idea of panmixia, it 

 becomes a most unaccountable fact that in his laborious essay 

 on " Degeneration " (1880) there is no hint of, or even the most 

 distant allusion to, this idea. Yet, in the presence of this idea, 

 " Hamlet " without the Prince of Denmark would be a highly 

 finished work compared with an essay on "Degeneration" 

 without any mention of panmixia. Therefore, here again, I can 

 only understand that Prof. Lankester has not even yet assimi- 

 lated " the idea in question." He confounds this idea with that 

 of the economy of growth : he fails to perceive the very 

 " essence " of the idea, in the all-important distinction between 

 selection as withdrawn and selection as reversed. Without ques- 

 tion, his essay on " Degeneration " proves a familiar acquaintance 

 with the doctrine that "the materials forming any part, if not 

 useful to the possessor, are saved as far as possible " ; but, most 

 emphatically, this is not " the idea of panmixia," while it is the 

 idea that is definitely "formulated " scores and scores of times 

 through all the editions of Mr. Darwin's works — an "idea," 

 therefore, which must necessarily have "occurred" to every 

 reader of those works since the time when Prof. Lankester 

 was at school. 



As this letter has already run to an inordinate length, I will 

 relegate to a footnote my discussion of the merely personal 

 criticisms which Prof. Lankester has passed upon my former 

 communication. 1 George J. Romanes. 



London, March 28. 



' Prof. Lankester says: — "As soon as the matter had taken root in his 

 mind, Mr. Romanes published in N.^tuub, March 12, April 7, and July 2, 

 1874, an exposition of the importance of the principle of cessation of selec- 

 tion as a commentary upon a letter by Mr. Darwin himself (Nati;re, vol. 

 viii. pp. 432, 505), in which Mr. Darwin had suggested that, w.th organisms 

 subjected to unfavourable conditions, all the parts would tend towards reduc- 

 tion. Mr. Darwin, with his usual kindly manner towards the suggestions of 

 a young writer, gives, at p. 309 of vol. ii. of 'AiOiimals and Plants under 

 Domestication,' Mr. Romanes's view, ' as fiir as it can be given in a few 

 Wjrds.'" Now, as it is only a few days ago. that I myself directed Prof^ 



