CHAPTER II 



VARIATION UNDER NATl/RE 



Variability— Individual differences— Doubtful species— Wide ranging, 

 much diffused, and common species vary most — Species of the 

 larger genera in any country vary more than the species of the 

 smaller genera — Many of the species of the larger genera resemble 

 varieties in being very closely, but unequally, related to each 

 other, and in having restricted ranges. 



Before applying the principles arrived at in the last 

 chapter to organic beings in a state of nature, we must 

 briefly discuss whether these latter are subject to any 

 variation. To treat this subject at all properly, a long 

 catalogue of dry facts should be given ; but these I 

 shall reserve for my future work. Nor shall I here 

 discuss the various definitions which have been given of 

 the term ' species. ' No one definition has as yet satisfied 

 all naturalists ; yet every naturalist knows vaguely 

 what he means when he speaks of a species. Generally 

 the term includes the unknown element of a distinct 

 act of creation. The term f variety ' is almost equally 

 difficult to define ; but here community of descent is 

 almost universally implied, though it can rarely be 

 proved. We have also what are called monstrosities ; 

 but they graduate into varieties. By a monstrosity I 

 presume is meant some considerable deviation of 

 structure in one part, either injurious to or not useful 

 to the species, and not generally propagated. Some 

 authors use the term ' variation ' in a technical sense, as 

 implying a modification directly due to the physical 

 conditions of life ; and ' variations ' in this sense are 

 supposed not to be inherited : but who can say that the 



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