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SCIENCE 



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



imagine " (kaum vorstellbar) . There is 

 hardly a single paper of Weismann on evolu- 

 tionary subjects ■which does not assure us of 

 this. But the reviewer has not seen in any 

 one of them a clear statement what these 

 doubts are, and his personal power of imagi- 

 nation, which surely has the same convincing 

 force as Weismann's, is entirely adequate to 

 admit this theory. Weismann's opinion to 

 the contrary and his idea of " germinal varia- 

 tion " is a working hypothesis pure and 

 simple, and should be used only as such; but 

 the two opposite views should never be used 

 as evidence against each other, and this is 

 what Weismann does again and again, also 

 in the present book. The Lamarchian prin- 

 ciple is wrong, because it is in conflict with 

 the Weismannian theory of the germ plasm, 

 and the latter is correct, hecause, since the 

 Lamarchian theory is wrong, it is the only 

 way to explain evolution. This is practically 

 the essence of Weismann's argumentation: a 

 schoolboy's blunder against logic. 



On the other hand, Weismann purposely 

 ■overlooks the recent experimental evidence 

 for the inheritance of acquired characters, 

 furnished now by quite a number of biolo- 

 gists. He knows, at any rate mentions, only 

 two of them, Semon and Kammerer, and says 

 that, according to Pfeffer, those of the first 

 are " incorrect " (nicht richtig) , and that he 

 is going to show that those of the latter can 

 not be regarded as convincing. The reviewer 

 is much afraid that this latter demonstration 

 will rest upon something like Weismann's 

 argument, which intended to show that his 

 own experiments on Polyommatus do not fur- 

 nish support for the Lamarekian view. As to 

 the latter, I beg to compare what I have said 

 some time ago with regard to this matter,' to 

 which I have to add nothing, and which 

 clearly shows that Weismann's conception of 

 the Lamarekian principle is entirely wrong, 

 in fact that he does not at all understand 

 what the essential point in it is. 



We may summarize our conclusions as to 

 the Weismannian theories and the Weismann- 



°See Biol. OentralU., 18, 1898, p. 153, and 

 Science, 23, June 22, 1906, p. 950. 



ism as follows: In the beginning, Weismann 

 proposed his theory of the germinal variation, 

 and the subsidiary theory of the all sufficiency 

 of natural selection in opposition to the cur- 

 rent view of the inheritance of acquired char- 

 acters, without positive support, but chiefly on 

 account of the supposed insufficiency of the 

 latter view. At that time it was a working 

 hypothesis as well as the other theory. In 

 his subsequent writings Weismann tried to 

 strengthen his position, but he was forced, 

 first of all, to abandon his idea of the 

 " amphimixis " as the cause of germinal varia- 

 tion, and further he introduced his theory of 

 the " germ plasm " and its variation, and, in 

 close connection with the latter, his theory of 

 inheritance. 



By the theory of the " variation of the 

 germ plasm " he changed his original views 

 of " germinal variation " in a fundamental 

 way," a fact which was never acknowledged 

 by him, and further, in connection with this, 

 he was forced to admit facts which are 

 strongly in favor of the Lamarekian prin- 

 ciple, which, however, he denied by the argu- 

 ment: if Lamarclcian inheritance can he ex- 

 plained hy the germ-plasm theory, there is no 

 Lamarchian inheritance. 



His special views on the principle of selec- 

 tion, although attacked repeatedly and dis- 

 proved, in part as incorrect, in part as illog- 

 ical, were always maintained and defended 

 by him, but only at the risk and to the detri- 

 ment of sound logic. At the present time, 

 in the booklet reviewed here, he is upon the 

 old standpoint; he has not considered valid 

 objections to his views, and has passed over 

 the most serious in silence, repeating again 

 and again his old blunders and absurdities. 



This has gone on too long. Weismannism 

 has become a term characterizing not only a 

 particular brand of Darwinism " made in 

 Germany," but also a particular kind of 

 loose and illogical reasoning, which we are 

 not wont to regard as a product of German 

 universities. This harsh criticism would not 

 be necessary but for the fact that Weis- 

 mannism has become a scientific " creed " 



" See Biol. CentralU., 18, 1898, p. 139 S. 



