NATURE 



[July 7, 19 10 



Herbert Spencer built upon their doing so his ethical 

 system. " Most biologists reject the Lamarckian 

 doctrine," on the ground that it is against the weight 

 of evidence. That is my own position. But the 

 author himself admits that there is some evidence in 

 its favour, yet unhesitatingly also rejects it on deduc- 

 tive grounds. The argument is rather subtle ; but it 

 amounts to this : a character which develops under 

 the stimulus of use cannot develop under the stimulus 

 of nutriment alone. If it did so it would be "a 

 miracle." But I am not sure that this is not an 

 assumption. In a unicellular organism the soma and 

 germ-plasm are identical, and as we rise in the scale 

 of plants the separation of the germ-plasm is far from 

 being as complete as it is in animals. In many 

 plants, as in the well-known case of Begonia, a 

 somatic cell will reproduce the whole individual, germ- 

 plasm and all. I am not prepared to assert that the 

 new germ-plasm is free from derived somatic influ- 

 ence. On the other hand, I know of no reason to 

 think that it is not. 



The Lamarckian doctrine being dismissed, natural 

 selection is examined. Like Prof. Karl Pearson, Dr. 

 Archdall Reid infers this immediately from "selective 

 mortality " in mankind. He points out that this 

 cannot be proved in the case of "wild plants and 

 animals," but "presumably" it occurs. I doubt if 

 disease is a dominant selective factor in nature, though 

 no doubt it has been occasionally operative, and on a 

 large scale. He puts the theory on too narrow a 

 basis, and ignores the struggle for existence. What 

 plants have to fight for is room to perfect their seeds 

 and space for them to germinate. 



This is not the only short cut to the root of the 

 matter. " The plain fact that living beings are able 

 to exist is a proof of adaptation." It does not appear 

 to me to be self-evident, though Paley would probably 

 have agreed. Anyhow, it is rather like trying to enter 

 Darwinism by the back-door instead of toiling up the 

 steps. I collect a somewhat better argument. Man 

 is "manifestly a bundle of adaptations." "The growth 

 of modern physiology implies merely an increased 

 power of interpreting human traits in terms of their 

 utilities." " Presumably adaptation is not less per- 

 fect in plants and lower animals than in man." Yet, 

 as Rolleston used to tell us at Oxford, that sort of 

 statement would not convict a poacher. Fortunately, 

 evolutionists have a better case for the court. 



Next we come to variation, which affords the 

 material for natural selection to work upon, and some 

 important conclusions are arrived at. Excluding any 

 possible influence of the soma, and I agree, variation 

 must be resident in the germ-plasm. " Reasoning by 

 analogy," it is inferred that this is itself "established 

 and maintained by natural selection." This involves 

 the paradox that it preceded that which produced it. 

 "Its origins are lost in obscurity." No doubt; but if 

 I may try my own hand at deduction, I would suggest 

 that primitive variation was a necessary consequence 

 of molecular instability, and as I regard natural selec- 

 tion as a sort of physical principle like "least action " 

 or gravitation, it would begin to operate at once. 



The most fundamental point in the whole argument 

 is the relation of the germ-plasm to the environment. 

 NO. 2123, VOL. 84] 



Here two classes of facts have to be faced; first, the 

 undoubted one, on which I have often insisted, that a 

 few years' cultivation of a wild species breaks down 

 its stabilitv; and, secondlv, such cases as the supposed 

 degeneration of European dogs in India. I can only 

 accept variation at present as an unresolved pheno- 

 menon. I have never contended that the environment 

 could act as more than a stimulus to it, and I have 

 no doubt that it does. Someone ' has used a 

 better expression in saying that it pulls the 

 trigger. To suppose that it has any directive 

 action lands one at once in Lamarckism. The 

 degeneration question is much more serious. To 

 attempt to get over it by saying that "evolution is 

 never perfect " and that " exceptions occur " is not 

 " facing the music." Now this story of the degenera- 

 tion of domestic animals and plants is an obsession 

 in India. I have had occasion to test it in the case 

 of the latter, and satisfied myself that it was due to 

 mongrelising ; and, as to Clayton's beans, I completely 

 exploded a similar case in Arabis some years ago in 

 these pages. My own conclusion is that variation is 

 inherent and spontaneous in the germ-plasm; and the 

 " germinal power of resisting enforced change " is an 

 undoubted fact which manifests itself in "specific 

 stability." 



The varying germ-plasm inherits and transmits 

 variations. Thus we are led to the thorny question 

 of recapitulation. Sedgwick agrees that it is "a de- 

 duction from the theory of evolution," but that it "is 

 still without satisfactory proof." On the other hand, 

 in the same volume, W. B. Scott finds that in brachio- 

 pods, "in the more advanced genera, the develop- 

 mental stages clearly indicate the ancestral genera of 

 the series." The botanist is constantly running up 

 against recapitulative structures. When he finds a 

 trace of a prothallus in a flowering plant and a sper- 

 matozoid in the pollen-tube of Salisburia, it is difficult 

 to avoid the conclusion of Bower that land-plants had 

 aquatic ancestors. We must, however, agree with 

 Prof. SoUas that "nature no doubt is a strict adherent 

 to logic, but she betrays a singular want of method in 

 recording the steps of her argument." 



Dr. Archdall Reid thinks, and no doubt rightly, that 

 " the main reason against a full acceptance of the 

 Darwinian doctrine" is "the retrogression of useless 

 parts and organs." His solution of this difficult problem 

 is one of the most novel and interesting things in his 

 book, and will probably be subjected to most criticism. 

 Thirty-two yearlings, costing 51,520 guineas, only pro- 

 duced two winners. From this and similar cases he 

 draws the inference that retrogression preponderates 

 over progression. He accounts for it by supposing 

 that there has been a selection of germ-plasms which 

 "tended on the whole to vary retrogressively." But 

 retrogression in turn " is checked only by selection." 

 The difficulty at once arises to reconcile this view with 

 the biometric result which he admits, that " variation 

 tends to occur about equally about the specific mean." 

 Incidentally it may be noted that he identifies retro- 

 gression with reversion. 



The various solutions of the problem which have 

 been attempted are discussed.' There is a risk that the 

 terminology used may cover a petitio principii. Given 



