CONCLUSION. 499 



ought not to believe that innumerable beings within each 

 great class have been created with plain, but deceptive, 

 marks of descent from a single parent. 



As a record of a former state of things, I have retained 

 in the foregoing paragraphs, and elsewhere, several sen- 

 tences which imply that naturalists believe in the separate 

 creation of each species; and I have been much censured 

 for having thus expressed myself. But undoubtedly this 

 was the general belief when the first edition of the preseut 

 work appeared. I formerly spoke to very many natural- 

 ists on the subject of evolution, and never once met with 

 any sympathetic agreement. It is probable that some did 

 then believe in evolution, but they were either silent or ex- 

 pressed themselves so ambiguously that it was not easy to 

 understand their meaning. Now, things are wholly 

 changed, and almost every naturalist admits the great prin- 

 ciple of evolution. There are, however, some who still 

 think that species have suddenly given birth, through quite 

 unexplained means, to new and totally different forms. 

 But, as I have attempted to show, weighty evidence can 

 be opposed to the admission of great and abrupt modifica- 

 tions. Under a scientific point of view, and as leading to 

 further investigation, but little advantage is gained by be- 

 lieving that new forms are suddenly developed in an inex- 

 plicable manner from old and widely different forms, over 

 the old belief in the creation of species from the dust of 

 the earth. 



It may be asked how far I extend the doctrine of the 

 modification of species. The question is difiBcult to 

 answer, because the more distinct the forms are which we 

 consider, by so much the arguments in favor of com- 

 munity of descent become fewer in number and less in 

 force. But some arguments of the greatest weight extend 

 very far. All the members of whole classes are connected 

 together by a chain of affinities, and all can be classed on 

 the same principle, in groups subordinate to groups. 

 Fossil remains sometimes tend to fill up very wide inter- 

 vals between existing orders. 



Organs in a rudimentary condition plainly show that an 

 early progenitor had the organ in a fully developed condi- 

 tion, and this in some cases implies an enormous amount 

 of modification in the descendants. Throughout whole 



