398 CONCLUSION. [CHAP. XV. 



ment from the mother's womb ? Undoubtedly some of these 

 same questions cannot be answered by those who believe in the 

 appearance or creation of only a few forms of life, or of some one 

 form alone. It has been maintained by several authors that it is 

 as easy to believe in the creation of a million beings as of one ; 

 but Maupertuis' philosophical axiom " of least action " leads the 

 mind more willingly to admit the smaller number ; and certainly 

 we 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 sentences 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 present work appeared. I formerly spoke to 

 very many naturalists 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 under- 

 stand their meaning. Now things are wholly changed, and almost 

 every naturalist admits the great principle 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 

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

 further investigation, but little advantage is gained by believing 

 that new forms are suddenly developed in an inexplicable 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 modifica- 

 tion of species. The question is difficult to answer, because the 

 more distinct the forms are which we consider, by so much the 

 arguments in favour of community 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 intervals between 

 existing orders. 



Organs in a rudimentary condition plainly show that an early 

 progenitor had the organ in a fully developed condition ; and this 

 in some cases implies an enormous amount of modification in the 

 descendants. Throughout whole classes various structures are 

 formed on the same pattern, and at a very early age the embryos 



