92 



NA TURE 



[November 25, 1909 



as "based on the conception of an inborn trans- 

 forming force violently discharged at regular intervals 

 by everv. species of times past, present and to come" — 

 a view on all fours with that upheld by the late Duke 

 of Argyll, and which formed the subject of a criticism 

 in these columns by the present writer at the time of 

 its promulgation ten years ago (vol. lix., p. 217). It is 

 the old "internal developmental force" let off sporadi- 

 cally instead of continuously, only subject, according 

 to the founder of the theory, to control by natural 

 selection. 



In the third appendix, as in his Oxford speech, the 

 author refutes once and for all the absurd and un- 

 warrantable conclusions respecting the mental 

 degeneration due to the exclusive pursuit of science 

 which certain writers have based upon Darwin's 

 description of his declining artistic faculties with the 

 advance of age. The last appendix is particularly 

 striking, as it brings out for the first time a remarkable 

 discrepancy between the views of the founder of the 

 modern theory of mutation (de Vries) and certain 

 English supporters of that theory (Bateson and 

 Punnett) respecting the fundamental question of the 

 transmissibility by inheritance of individual differences 

 or " fluctuations." According to de Vries these 

 fluctuations are transmissible ; if they are not, the 

 whole fabric of the Darwinian theory is, it is needless 

 to point out, overturned. The elucidation of this 

 point seems to be one of the most urgent problems 

 awaiting attack b\' experiment. 



The valuable contributions to the Darwinian theory 

 with which the author of the present work has been 

 for so many years identified have been mainly in that 

 most fascinating field of the relationship between the 

 •colours of animals and their environment — a subject 

 which first led the present writer to the serious study 

 -of the " Origin of Species " more than thirty years ago. 

 In this class of phenomena, adaptation is obvious to 

 those who do not wilfully close their eyes to the 

 evidence. If this adaptation is not explicable 

 "by natural selection, then that principle can be 

 ■applicable in no other department of organic nature, 

 it is not going too far to say that with the proof or 

 ■disproof of the utility of these resemblances in colour, 

 form, pattern and habit which are so abundant in the 

 Insect world, the whole question of the validity of the 

 Darwinian theory is bound up. Darwin himself fore- 

 shadowed this application ; so also did Wallace. Bates, 

 Wallace, and Roland Trimen applied it to mimetic 

 resemblances, Thomas Belt was a contributor, and 

 Fritz Miiller in 1879 ga'^'e "s a new and important lead. 

 Its application to the development and use of the 

 markings of caterpillars was among the early and by 

 no means least important of the contributions to 

 biological science by August Weismann. No writer 

 in modern times has done more than Prof. Poulton 

 tj place this application of Darwin's theorv upon a 

 sound scientific basis, and not the least interesting of 

 his contributions is to be found in the sixth chapter 

 of the present work, wherein he traces with masterly 

 hand the mimetic influence exerted by certain Old 

 World butterflies upon the insects of the New World 

 into which they are comparatively recent immigrants. 

 Such a clear case as this, in which the direction of 

 NO. 2091, VOL. 82] 



modification is not open to doubt, disposes at once of 

 the theory that similar environmental influences pro- 

 duce similarity of colour and pattern, for here it is 

 the old inhabitants of the country and not the later 

 immigrants that have been modified in the direction 

 of mimetic resemblance. 



It may be permissible on the present occasion to 

 extend one's contemplation of the book immediately 

 under notice to certain wider considerations which 

 arise from the work which has for so manv years been 

 carried out in the Hope Department of the University 

 of Oxford. That work bears throughout the stamp 

 of Darwin's influence, and stands as living testimony 

 that the central doctrine proclaimed in the " Origin 

 of Species " half a century ago is still a vitalising 

 power. It will not be considered presumptuous to 

 recommend to a generation which has been told that 

 the species question is not even ripe for discussion a 

 critical re-perusal of Darwin's classic. Thereby it will 

 bv- made evident that for the author of that work, 

 nature was a living whole — a frame of mind from 

 which modern specialisation is unfortunately leading 

 many of the younger workers astray. The breadth of 

 view which enabled the author of the " Origin " to 

 mould whole branches of science into his service must 

 for all time be a matter for admiration and wonder- 

 ment. How comprehensive that view really is may 

 be inferred from the circumstance that there is 

 scarcely one modern development of the species ques- 

 tion — perhaps none with the exception of the long 

 neglected work of Mendel — which in principle, if not 

 in detail, is not foreshadowed in the "Origin." Even 

 tho all-important question of the transmission of 

 acquired characters appears to have been raised, and 

 to have been considered by Darwin, as may be 

 gathered from an apparently forgotten passage in the 

 " Origin " to which the writer has directed Prof. 

 Poulton 's attention, and which is quoted fully in the 

 last appendix to the volume under consideration 



(p. 273)- 



Some other lessons conveyed by Darwin's "Origin 

 of Species " may perhaps be worthy of consideration 

 at the present time. We have heard much of late 

 years about the want of public interest in science being 

 due to the technical and popularly unintelligible 

 language in which investigators express their results. 

 The answer to that charge can best be given by 

 pointing to Darwin's writings as a whole; these, 

 although scientific in the technical sense, being 

 nevertheless popular in treatment and commanding a 

 sale never before realised by any set of treatises on 

 purely scientific subjects. From this experience it is 

 fair to conclude that unintelligibility is at any rate not 

 a necessary accompaniment of sound scientific 

 exposition. 



The tendency to specialisation which is becoming 

 more and more characteristic of modern scientific 

 work is not in itself an unhealthy sign. It is the 

 necessary consequence of the growth of knowledge on 

 the one hand and of the limitation of the human 

 intellect on the other. All the good work turned out 

 by our investigators at the present time is the result 

 of such specialisation. As time goes on, the increase 

 in the mass of material and in the number of workers 



