120 OTHER FACTOES OF EVOLUTION 



and were strongly reinforced two years later by the publication of 

 his essay on "The Continuity of the Germ- Plasm." ' In a later 

 essay in the same volume, he says (p. 399) : — " I think it is now 

 generally admitted that a very important problem is involved in 

 this question, the solution of which will contribute in a decisive 

 manner towards the formation of ideas as to the causes which Jiave 

 produced the transformation of species. For if acquired characters 

 cannot be transmitted, the Lamarckian theory completely collapses, 

 and we must entirely abandon the principle by which alone 

 Lamarck sought to explain the transformation of species, — a prin- 

 ciple of which the appUcation has been greatly restricted by 

 Darwin in the discovery of natural selection, but which was still to 

 a large extent retained by him." Weismann came to the conclusion 

 that acquired characters cannot be transmitted, because, as he 

 thought, there were no proofs of such transmission, and because its 

 occurrence was theoretically improbable, or even ' inconceivable,' 

 as some of his followers say.^ 



It is well never to lose sight of the fact that opposition to the 

 view that functionally acquired characters are inherited is essentially 

 associated with Weismann's doctrine of the 'Continuity of the 

 Germ-Plasm,' and the other hypotheses founded thereupon. We 

 have seen (pp. 76-81) how void of foundation in fact this doctrine is 

 — and how much it is actually opposed to multitudes of facts which 

 have been made known since the time when it was first enunciated. 

 As a consequence, his sequential doctrine that changes undergone 

 by the cells and tissues of the body generally are unable to produce 

 any effect in the transformation of species, " simply because they 

 can never reach the germ-cells from which the succeeding genera- 

 tion arises," becomes robbed of its principal support. And as to 

 the alleged improbability, or inconceivability, of any means by 

 which the germ-cells may be specifically altered as a result of 

 changes taking place in the soma by use and disuse, or by the 



» See his "Essays on Heredity," Transln., 2nd Edn., 1891, Vol. I, pp. 67 and 

 163. 



' In the early days of this discussion far too much importance was attached to 

 the fact that mutilations are not inherited. But these occur for the most part 

 once only in the life of an individual, and are mostly experienced by one sex 

 only, so that it is as Cope says {loc. cit. p. 400) : " quite unreasonable to cite the 

 history of mutilations as evidence against the inheritance of natural characters 

 produced by oft-repeated and long continued natural causes." Still, some well 

 authenticated cases of the inheritance of mutilations have been recorded by him 

 (p. 431). 



