4 Darwin, and after Darwin. 



less and walks more than the wild duck, and its limb bones 

 have become diminished and increased in a corresponding 

 manner in comparison with those of the wild duck. A horse is 

 trained to certain paces, and the colt inherits similar consensual 

 movements. The domesticated rabbit becomes tame from 

 close confinement ; the dog, intelligent from associating with 

 man ; the retriever is taught to fetch and carry ; and these 

 mental endowments and bodily powers are all inheriter', 

 Nothing in the whole circuit of physiology is more wonderfi; . 

 How can the use or disuse of a particular limb or of the bra.n 

 affect a small aggregate of reproductive cells, seated in a distant 

 part of the body, in such a manner that the being developed 

 from these cells inherits the characters of either one or both 

 parents ? . . . In the chapters devoted to inheritance, it was 

 shown that a multitude of newly acquired characters, whether 

 injurious or beneficial, whether of the lowest or highest vital 

 importance, are often faithfully transmitted '.'' 



"When discussing special cases, Mr. Mivart passes over the 

 effects ot the increased use and disuse of parts, which I have 

 always maintained to be highly important, and have treated in 

 my 'Variation under Domestication' at greater length than, 

 as I believe, any other writer '. ' 



So much for the matured opinion of Darwin touching 

 the validity of the theory of use-inheritance. Turning 

 now to his opinion on the question whether or not 

 there are yet any further factors concerned in the 

 process of organic evolution, I think it will be sufficient 

 to quote a single passage from the Origin of Species. 

 The first paragraph of the " Conclusion " is devoted 

 to a rhume of his views upon this matter, and con- 

 sists of the following most emphatic words. 



" I have now recapitulated the facts and considerations which 

 have thoroughly convinced me that species have been modified, 

 during a long course of descent. This has been effected chiefly 

 through the natural seleciion of numerous successive, slight, 



» Variation &.c. ii. p. 367. » Ori^n of Species, p. 176. 



