Chap. XIII. CLASSIFICATION. 423 



it would connect together all languages, extinct and 

 modern, by the closest affinities, and would give the 

 filiation and origin of each tongue. 



In confirmation of this view, let us glance at 

 the classification of varieties, which are believed or 

 known to have descended from one species. These 

 are grouped under species, with sub-varieties under 

 varieties; and with our domestic productions, several 

 other grades of difference are requisite, as we have 

 seen with pigeons. The origin of the existence of 

 groups subordinate to groups, is the same with varieties 

 as with species, namely, closeness of descent with various 

 degrees of modification. Nearly the same rules are fol- 

 lowed in classifying varieties, as with species. Authors 

 have insisted on the necessity of classing varieties on a 

 natural instead of an artificial system ; we are cau- 

 tioned, for instance, not to class two varieties of the 

 pine-apple together, merely because their fruit, though 

 the most important part, happens to be nearly identical ; 

 no one puts the Swedish and common turnips together, 

 though the esculent and thickened stems are so similar. 

 Whatever part is found to be most constant, is used 

 in classing varieties : thus the great agriculturist Mar- 

 shall says the horns are very useful for this purpose 

 with cattle, because they are less variable than the 

 shape or colour of the body, &c. ; whereas with sheep 

 the horns are much less serviceable, because less con- 

 stant. In classing varieties, I apprehend if we had a 

 real pedigree, a genealogical classification would be 

 universally preferred; and it has been attempted by 

 some authors. For we might feel sure, whether there 

 had been more or less modification, the principle of 

 inheritance would keep the forms together which were 

 allied in the greatest number of points. In tumbler 

 pigeons, though some sub-varieties differ from the others 



