348 CLASSIFICATION. [CHAP. XIV. 



be expressed by ranking them under different so-called genera, 

 sub-families, families, sections, orders, and classes. 



It may be worth while to illustrate this view of classification, 

 by taking the case of languages. If we possessed a perfect pedi- 

 gree of mankind, a genealogical arrangement of the races of man 

 would afford the best classification of the various languages now 

 spoken throughout the world ; and if all extinct languages, and 

 all intermediate and slowly changing dialects, were to be included, 

 such an arrangement would be the only possible one. Yet it 

 might be that some ancient languages had altered very little and 

 had given rise to few new languages, whilst others had altered 

 much owing to the spreading, isolation, and state of civilisation 

 of the several co-descended races, and had thus given rise to 

 many new dialects and languages. The various degrees of differ- 

 ence between the languages of the same stock, would have to be 

 expressed by groups subordinate to groups; but the proper or 

 even the only possible arrangement would still be genealogical; 

 and this would be strictly natural, as it would connect together 

 all languages, extinct and recent, 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 known or believed to be descended from 

 a single species. These are grouped under the species, with the 

 sub-varieties under the varieties ; and in some cases, as with the 

 domestic pigeon, with several other grades of difference. Nearly 

 the same rules are followed as in classifying species. Authors 

 have insisted on the necessity of arranging varieties on a natural 

 instead of an artificial system; we are cautioned, 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 turnip 

 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 Marshall 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 constant. 

 In classing varieties, I apprehend that if we had a real pedigree, 

 a genealogical classification would be universally preferred ; and 

 it has been attempted in some cases. For we might feel sure, 

 whether there had been more or less modification, that the prin- 

 ciple of inheritance would keep the forms together which were 

 allied in the greatest number of points. In tumbler pigeons, 

 though some of the sub- varieties differ in the important character 

 of the length of the beak, yet all are kept together from having 

 the common habit of tumbling; but the short-faced breed has 



