THEORY OF NATURAL SELECTION 229 



of natural selection. For the best definition which has ever 

 been given of a high standard of organisation is the degree 

 to which the parts have been specialised or differentiated; 

 and natural selection tends towards this end, inasmuch as 

 the parts are thus enabled to perform their functions more 

 efficiently. 



A distinguished zoologist, !Mr. St. George Mivart, has 

 recently collected all the objections which have ever been 

 advanced by myself and others against the theory of natural 

 selection, as propounded by Mr. Wallace and myself, and has 

 illustrated them with admirable art and force. When thus 

 marshalled, they make a formidable array ; and as it forms 

 no part of Mr. Mivart's plan to give the various facts and 

 considerations opposed to his conclusions, no slight effort 

 of reason and memory is left to the reader, who may wish 

 to weigh the evidence on both sides. When discussing special 

 cases, Mr. Mivart passes over the effects of 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. He likewise often assumes that I attribute nothing 

 to variation, independently of natural selection, whereas in 

 the work just referred to I have collected a greater number of 

 well-established cases than can be found in any other work 

 known to me. My judgment may not be trustworthy, but 

 after reading with care Mr. Mivart's book, and comparing 

 each section with what I have said on the same head, I never 

 before felt so strongly convinced of the general truth of the 

 conclusions here arrived at, subject, of course, in so intricate 

 a subject, to much partial error. 



All Mr. Mivart's objections will be, or have been, con- 

 sidered in the present volume. The one new point which 

 appears to have struck many readers is, "that natural selec- 

 tion is incompetent to account for the incipient stages of 

 useful structures." This subject is intimately connected with 

 that of the gradation of characters, often accompanied by 

 a change of function, — for instance, the conversion ^ of a 

 swim-bladder into lungs, — points which were discussed in the 

 last chapter under two headings. Nevertheless, I will here 



