816 



SCIENCE 



[N. S. Vol. XXXI. No. 804 



and serious objections to them advanced by 

 various adversaries. 



The title of the present booklet might sug- 

 gest that Weismann had the intention of 

 doing something like this, for his conception 

 of the principle of selection is one of his 

 chief peculiarities, which has been most vig- 

 orously attacked. But perusing this book, we 

 find that not the slightest attempt has been 

 made to discuss seriously these objections. 

 Here and there a feeble show is made, as if he 

 had paid attention to them, but generally he 

 discusses only minor points, and avoids the 

 most essential criticisms, those which, when 

 admitted as correct, would inflict the finish- 

 ing blow to that particular type of evolution- 

 theory known as W eismannism. And further, 

 a peculiar feature of the present book is that 

 in certain cases Weismann admits that his 

 critics are right in a particular point, but 

 that he nevertheless insists in maintaining 

 his old position and his old views about this 

 point. We occasionally have come across this 

 way of arguing in informal discussions with 

 persons belonging to the weaker sex, but 

 never, as far as we can remember, in a sci- 

 entific treatise which pretends to be serious. 



The whole book is an eulogy on selection 

 and its power to create new things. Weis- 

 mann believes, if this is admitted, then there 

 will be no difficulty whatever in understand- 

 ing the origin of the whole organic world, and 

 consequently also the origin of new species 

 by natural selection will be clear. He claims 

 that he stands, in maintaining this view, 

 upon the original standpoint of Darwin. But 

 Darwin never said that new species are cre- 

 ated hy natural selection. Indeed, there is the 

 title of Darwin's book, " The Origin of 

 Species by Means of Natural Selection," and 

 it must be confessed that, reading the title 

 alone, it might be interpreted this way. But 

 there are some people who have a habit of 

 looking more closely at things, books espe- 

 cially, and when they began to read Darwin's 

 book, they found out that there is a distinc- 

 tion of two processes within the whole great 

 process of evolution : the one is the transfor- 

 mation of species, that is to say, the change 



of one existing form of life into one other 

 one, and the other is the differentiation of 

 species, that is to say, the dividing of one ex- 

 isting form into two or more other ones. The 

 latter process is strictly the origin of new 

 species, or, as it has recently been called, the 

 process of speciation. 



For the first process, the transformation of 

 species, Darwin introduces the three factors: 

 Variation, Inheritance and Natural Selection' 

 and treats of them in the first five chapters. 

 But incidentally he also discusses the second 

 process, the origin of new species. He does 

 this chiefly in the fourth chapter, where he 

 talks of the divergence of character.^ As the 

 writer has shown elsewhere,* Darwin feels a 

 little uneasy about this point. Nevertheless, 

 he gives a tentative answer, and this is, that 

 new species originate, if they are " enabled 

 to seize on many and widely diversified places 

 in the polity of nature,"" or, " if (they) be- 

 come fitted for . . . different habits of life or 

 conditions."" This is exactly what by subse- 

 quent writers has been called separation, iso- 

 lation, bionomic separation, and for which 

 possibly the best term is " ecological segrega- 

 tion." And I hope by mentioning these words 

 Weismann may recollect that they are in- 

 tended to express something, and that they 

 are supposed to have a definite place within 

 the evolution-theory. In fact, the working 

 out of this principle is the most essential im- 

 provement added by subsequent writers to 

 Darwin's theory. 



The above distinction between transforma- 

 tion of species (Umwandlung der Arten) and 

 the origin of new species (Entstehung neuer 

 Arten) has been exposed again and again, 

 has been discussed at such a length that it 

 has actually become tiresome to have to re- 

 peat it. Any child should be able to see the 

 point. But Weismann evidently fails to do 

 so. All his previous writings, and also the 

 present book, are, with reference to the dis- 



^ See summary at end of chapter IV., p. 102 

 ("Origin of Species," American ed., 1884). 



'Ibid., p. 86. 



'Pr. Am. Phil. Sac, 35, 1896, p. 175 ff. 



" " Origin of Species," p. 87. 



'Ibid., chapter VII., p. 169. 



