202 



NA TURE 



[December 27, 1900 



surface of the wing, the aspect that would be first seen by 

 the female if the male were flying straight towards her. 

 Nowhere is this iridescent colouring better seen, by the 

 way, than in the male Hypolimnas bolina, figured by the 

 author on p. 233. 



Although there can be no doubt that Mr. Cunningham's 

 plea for Lamarckism and the inheritance of acquired 

 characters is on the whole very ably supported, it will not 

 fail to strike many of his opponents that his anti-selec- 

 tionist zeal carries him too far in some of his most 

 fundamental arguments. Like many of the recent critics 

 of Darwinism, the author now and again reads into the 

 theory of selection certain deductions of his own, which 

 he then proceeds to demolish without considering 

 whether his deductions are legitimate or not. For 

 example, he considers it an objection to the Darwinian 

 explanation of flying mammals (p. 15) that 



" the variations in the condition of the skin in animals 

 that do not fly or take long leaps through the air are not 

 such as to justify the belief that these variations would 

 make any difference in the struggle for existence when 

 long leaps became necessary." 



That is to say that other animals besides those that do 

 fly might be expected to show, on occasion, the raw ma- 

 terial, so to speak, for potential flight. This is a kind of 

 argument which has constantly been used by anti- Dar- 

 winians. Why, because a certain species has been enabled 

 to develop such and such a useful character, have not 

 similar characters been developed in other species to 

 which they might be equally useful ? It appears to be 

 again necessary to point out (i) that it is not part of the 

 Darwinian theory to suppose that every species is capable 

 of varying in every possible direction ; (2) that modification 

 in the direction of flight may not have been possible in 

 the species which " do not take long leaps through the 

 air" ; and (3) that such species have, no doubt, survived 

 by the development of some other method of escape or 

 defence which is quite as effective. Arguments of this 

 sort might equally well be urged against the Lamarckians. 

 Why, for instance, do not the flying lemurs, squirrels and 

 foxes, &c., fly as well as bats, seeing that the mem- 

 branous expansion of skm is constantly being used for 

 gliding through the air ? The writer has no desire to 

 press this point against the author of the present work. 



Then, again, Mr. Cunningham insists frequently that 

 his (Lamarckian) explanation accounts for unisexual 

 inheritance, while sexual selection does not. I believe 

 that I shall not be singular in declaring my inability to 

 see any force in this argument. Inheritance, as limited 

 by sex, is a fact. Mr. Cunningham says {e.g. on p. 252) 

 that this limitation is due to the "stimulations" having 

 been applied to one sex and not to the other. But even 

 if this were the true origin of the male characters there 

 is absolutely nothing in the Lamarckian explanation 

 which accounts for their non-transmission to the female. 

 All characters, whether secondary sexual or not, must on 

 either hypothesis (Lamarckian or Darwinian) originate in 

 an individual, which individual must — it is needless to 

 say in the case of bisexual animals — be either male or 

 female. Why, then, should there ever be any blending 

 of characters at all ? According to Darwin's theory, the 

 male characters originate through the selection of spon- 

 taneous variations by the females ; according to the 



amended Lamarckism, the male characters are, as it 

 were, hammered out of the male by stimuli applied at 

 the period of sexual maturity. Why should this latter 

 view be supposed to account for the limitation of the male 

 characters to the male, and the former view (Darwin's) to 

 fail ? Or, to put the case in another way : Why should 

 characters impressed mechanically upon the male during 

 a particular period of his life be hereditary, and .characters 

 arising by spontaneous variation at that period not be 

 hereditary ? If the author had contented himself with 

 the acknowledgment that unisexual inheritance required 

 further explanation, both schools of biologists would 

 agree. The selectionists might even have suggested an 

 answer on the lines laid down by Wallace — that the 

 female, being in most cases in greater need of protection 

 and concealment, had had any tendency to inherit the 

 male characters eliminated by natural selection. The 

 author will no doubt reject this explanation ; but whether 

 he does so or not, it is manifestly absurd to claim for 

 Lamarckism a fictitious superiority as regards the ex- 

 planation of unisexual inheritance. The advantage seems 

 to the writer to be distinctly on the side of the Darwinians. 

 If, as we believe, this latest attempt to reinstate 

 Lamarckian evolution is unsuccessful, its failure is due 

 to the inherent weakness of the doctrine rather than to 

 the treatment which it has received in the present volume. 

 It was an excellent idea on the part of Mr. Cunningham 

 to test this theory by applying it to secondary sexual 

 characters, but it does not appear that the light shed by 

 Lamarckian assumptions is in any way clearer than that 

 offered by the theory of sexual selection. There are, 

 confessedly, difficulties in the way of both theories, but 

 those offered by the Lamarckian doctrine are certainly 

 the more serious. The writer, at any rate, has come to 

 the conclusion that few biologists in this country wil 

 accept the mass of material offered in the present volume 

 as "inductive evidence" in favour of the heredity of 

 acquired characters. Most of the cases discussed are 

 equally well explained by the theory of selection — some 

 cases are better explained by this theory. Assumptions 

 and deductions have to be made by the supporters of 

 both theories ; those required by the Lamarckians seem 

 to be much the less warrantable. It may be fairly said 

 that if Lamarckism breaks down in its application to 

 such characters as those dealt with, its career as a work- 

 ing hypothesis has ended fatally. It would certainly be 

 interesting to know whether the author limits his 

 Lamarckism to the production of secondary sexual 

 characters, or whether he regards his amended form of 

 the theory applicable to all specific characters. Limita- 

 tion hardly seems possible logically, because any stimulus 

 or impact of any kind whatever must (on this hypothesis) 

 produce its effect if applied at the right stage of physio- 

 logical activity. The author, if he accepts this wider 

 application, will thus have narrowed down the issue be- 

 tween the two schools of evolutionists to the simple 

 question whether hereditary modifications can be pro- 

 duced by such means. We believe the answer will be 

 in the negative, but if this wider view is not accepted, 

 then Mr. Cunningham must show cause why the modi- 

 fication should be restricted to such characters as those 

 which he has so ably discussed in the volume which has 

 been considered in this notice. R. Meldola. 



NO. 1626. VOL. 



63] 



