CHAPTER II 



Variation Under Nature 



Variability — Individual Differences — Doubtful Species — Wide ranging, much 

 diffused, and common Species, vary most — Species of the Larger Genera 

 in each Country vary more frequently 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 prop- 

 erly, a long catalogue of dry facts ought to be given ; but these I 

 shall reserve for a future work. Nor shall I here discuss the various 

 definitions which have been given of the term species. No one 

 definition has 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 'Variety" is almost equally difficult to define; but here 

 community of descent is almost universally implied, though it ccn 

 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, generally injurious, or 

 not useful to the species. 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 sup- 

 posed not to be inherited; but who can say that the dwarfed con- 

 dition of shells in the brackish waters of the Baltic, or dwarfed 

 plants on Alpine summits, or the thicker fur of an animal from far 

 northward, would not in some cases be inherited for at least £ few 

 generations? And in this case I presume that the form would be 

 called a variety. 



It may be doubted whether sudden and considerable deviations 

 of structure, such as we occasionally see in our domestic produc- 

 tions, more especially with plants, are ever permanently propa- 

 gated in a state of nature. Almost every part of every organic 

 being is so beautifully related to its complex conditions of life that 



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