August 30, 1888] 



NATURE 



4*3 



"nascent organs will rarely have been handed down, . . . for beings 

 with any important organ but little developed will generally 

 have been supplanted by their descendants with the organ well 

 developed" (" Life and Letters," vol. ii. p. 214). If, however, 

 the Duke of Argyll is prepared to furnish a chapter upon the 

 evidences of "prophetic germs," with which he appears to be 

 extensively acquainted, he will confer a favour upon the waiting 

 scientific world by publishing it. 



With regard to the utility of rudimentary organs, the Duke 

 has perverted entirely the doctrine given by Darwin, who 

 certainly did not ascribe "all organic structures to utility as a 

 physical cause," while even if that were the case, the doctrine 

 of prophetic germs is in no way opposed to it. In his lengthy 

 letter to Lyell, which probably the Duke has in his mind, 

 Darwin remarks : — "A nascent organ, though little developed, 

 as it has to be developed, must be useful in every stage of 

 development. As we cannot prophesy, we cannot tell what 

 organs are now nascent "(" Life," ii. p. 213). This observa- 

 tion, before it can be properly understood, however, requires to 

 be amplified by reference to the full text from which it was 

 abstracted, in which the following remarks also occur : — "In 

 many cases we are far too ignorant to be enabled to assert that 

 a part or organ is so unimportant for the welfare of a species 

 that modifications in its structure could not have been slowly 

 accumulated by means of natural selection. In many other 

 cases modifications are probably the direct result of the laws of 

 variation, or of growth, independent of any good having thus 

 been gained " ("Origin," pp. 165-66). Yet natural selection 

 "will never produce in a being any structure more injurious 

 than beneficial to that being " (p. 162), and Darwin fully held 

 that it does not necessarily lead to "absolute perfection," which, 

 indeed, would almost amount to a denial of the necessity of 

 variation. Furthermore, "useful organs, however little they 

 may be developed, unless we have reason to suppose that they 

 were formerly mure highly developed, ought not to be con- 

 sidered as rudimentary. They may be in a nascent condition, 

 and in a progress towards further development. Rudimentary 

 organs, on the other hand, are either quite useless ... or 

 almost useless ; . . . they cannot have been produced through 

 variation and natural selection, which act solely by the preserva- 

 tion of useful modifications. They have been partially retained 

 by the power of inheritance, and relate to a fjrmer state of 

 things" (et seq , ' Origin," p. 398). 



The above references I have quoted somewhat fully, because 

 they appenr to me to present a complete disavowal of the two 

 assertions made by the Duke of Argyll, namely (1) that the 

 physical cau-e of all organic structures is ascribed to utility ; 

 and (2) that functionless organs "are never interpreted as 

 utilities which are yet to be." William White. 



August 18. 



Lamarckism versus Darwinism. 



Mr. Poulton says it is to be regretted that I have not written 

 anything which can be considered as a reply to his previous 

 letter. But this is exactly what I did. In that letter he merely 

 made the bald statement that I had not acquainted myself with 

 the views of Prof. Weismann, which I had " professed to 

 express." This statement I denied, and what further "reply" 

 it admits of I must leave Mr. Poulton to explain. 



Regarding his present suggestion, that it would be well for me 

 to justify a remark in the ( ontemporary Review, which he chal- 

 lenged, I can only repeat that 1 have no desire to continue a 

 correspondence which was opened in the manner alluded to. 

 And, in repeating this plain statement, I am as far as ever from 

 experiencing any of the "annoyance" which he says I have 

 taken no pains to conceal. Unless by annoyance he means sur- 

 prise, I am at a loss to understand why he should suppose that 

 I entertain any feeling of the kind. 



Prof. E. Nay Lankester's views "upon the interesting question 

 of Lamarck Versus Darwin " are, of course, well known to all 

 biologists ; but I think it is somewhat too strong a statement to 

 say that they are " diametrically opposed " to mine. No doubt 

 he has been more influenced by Prof. Weismann's recent 

 theories ; but I feel sure he would agree with me that the time 

 has not yet come for the formation of any matured "opinion" 

 upon this- subject. 



Prof. Meldola is kind enough to express disappointment that I 

 have not given a more explicit statement of my views on 

 the theoretical bearings of Mr. I'oulton's experiments. The tone 



of this invitation induces me to comply with his request. But 

 in order to do so it will be necessary to go at considerable length 

 into the whole question of " Lamarckism versus Darwinism." 

 As this has now become a very extensive and somewhat involved 

 question, I cannot feel that the correspondence columns of 

 Nature afford a suitable place for its discussion. But I will 

 bear the matter in mind, and, as soon as other work shall have 

 been cleared off, will publish an essay upon the whole subject. 

 Mr. Poulton, too, will ihen find that it is easy enough to "notice 

 the criticism," without requiring "to show that his [my] remark 

 about Prof. Weismann is intended to bear some other than its 

 obvious meaning." 



Meanwhile, I should like to represent how undesirable it is to 

 employ phraseology which associates the name of Darwin with 

 the post-Darwinian theories which are in question. Here, for 

 instance, we have a correspondence headed " Lamarckism Tersus 

 Darwinism" where the title ought to be "Darwinism versus 

 Weismannism " ; and while on the one hand Prof. Meldola 

 speaks of " the recent revival of 'pure' Lamarckism," on the 

 other he alludes to Prof. Weismann's interpretations as those 

 which belong to "the purely Darwinian stand-point." The 

 consequence of this kind of writing is that anyone who, like my- 

 self, still retains unmodified the Darwinism of Darwin himself, 

 is ticketed as a follower of Lamarck. Therefore, if only as a 

 matter of historical accuracy, and in order to avoid confusion in 

 non- biological circles, it seems to me that such terms ought to be 

 avoided. Most people will always understand that "Darwin- 

 ism '' is intended to meav the theory of evolution as held by 

 Darwin, yet this is just the very thing that it is not intended to 

 mean by your other correspondents: the more "pure" their 

 "Darwinism," the further does it depart from the doctrine 

 of evolution as presented in the "Origin of Species." As a 

 matter of fact, there has been no "recent revival of 'pure' 

 Lamarckism " : there has merely been a question raised as to 

 whether the amount of Lamarckism which was sanctioned by 

 Darwin may not be dispensed with. Now, not only is this 

 question, as already remarked, post-Darwinian in its origin, but 

 the speculations which have given rise to it are ultra- Darwinian 

 in their object : they aim at establishing for natural selection a 

 sole and universal sovereignty which was never claimed for it 

 by Darwin himself. Far be it from me to pre-judge a question 

 which must assuredly involve a large amount of future research ; 

 but however this question may eventually be decided, there is 

 no need to confuse the issues by the use of historically in- 

 accurate terms. The school of Weismann may properly be 

 called Neo-Darwinian : pure Darwinian it certainly is not. 



George J. Romanes. 



Geanies, Ross-shire, N.B., August 26. 



A Substitute for Carbon Disulphide in Prisms, &c. 



It may be worth mentioning that the highly-refractive liquid, 

 phenyl-thiocarbimide (molecular formula, C B H 5 NCS), to which 

 I drew attention some little time ago at a meeting of the Physical 

 Society (see Nature, vol. xxxvii. p. 165), can now be obtained 

 as an ordinary article of commerce from Schuchardt, of Gorlitz, 

 and Kahlbaum, of Berlin. 



I have recently again determined its refractive indices for dif- 

 ferent rays, but the values (when allowance is made for temper- 

 ature) do not appreciably differ from my former results, or from 

 those given by Nasini [Atti R.A. dei Lyncei, June 20, 1886) for 

 the substance which he calls " iso-solfocianato-fenilico," as Dr. 

 Gladstone has kindly mentioned to me since the meeting. Thus, 

 taking rays near the ends of the visible spectrum, I find (at a 

 temperature of io° C.) — 



The coefficient of dispersion, calculated from the above values, 

 is o - o68, rather higher than even that of carbon disulphide for 

 the same rays, which is 0*062. 



Phenyl-thiocarbimide seems, in fact, to have about the highest 

 refractive and dispersive power of any fairly permanent co'ourless 

 liquid known at present. Carbon disulphide, though colourless 

 when pure, is apt to turn yellow with age and exposure to light, 

 and monobromonaphthalene has an incurably yellow colour (as 

 also has mercury barium iodide), which of course implies an 

 absorptive action on the more refrangible part of the spectrum. 



* Not A, a* pri ted in Nature {toe. cit.). The index for A is i'6^[2. 



