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ii08 THE ORIGIN OF SPECIES 



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 in- 

 vestigation, 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 

 modification of species. The question is difficult to 

 answer, because the more distinct the forms are which 

 we consider, by so much the arguments in favor 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 rudimeutary 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 closely 

 resemble each other. Therefore I <)annot doubt that 

 the theory of descent with modification embraces all the 

 members of the same great class or kingdom. I be^ 



