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Show 422 CLASSIFICATION. CHAP. XIII. l1 ave I· n h eri' ted to a certain extent their c.h aracte. rs. This natural arrangement is sho~n, as far as IS possible on paper, in the diagram, but In much too simple a manner. If a branching diagram had not bee~ used, and only the names of the groups h~d been wnt~en in a linear series it would have been still less possible to have given a ~atural arra~gement? and it is notoriously not possible to represent _In a s~nes, on a flat surface, the affinities which we discover In nature amongst the beings of the same group. Thus, on the view which I hold, the natural system is genealogical in its arrangement, like a pedigree; but the degrees of modification which the different groups have undergone, have to 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 classi-fication, · by taking the case of languages. If we possessed a perfect pedigree 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, had to be included, such an arrangement would, I think, be the only possible one. Yet it might be that soine very ancient language had altered little, and had given rise to few new languages, whilst others (owing to the spreading and subsequent isolation and states of civilisation of the several races, descended from a common race) had altered much, and had given rise to many. new languages and dialects. The various degrees of difference in the languages from the same stock, would have to be expressed by groups ~ubordinate to groups ; b~1 the proper or even only possible arrangement would stil be genealogical; and this would be strictly natural, as 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 followed 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 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 turn1ps 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 b~d y, &c. ; whereas with sheep the horns are much less serviceable, because less constant. 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 n1odification, the principle of inheritance would keep the forn1s together which were ~Hied in the greatest number of points. In tumbler pigeons, though some sub-varieties differ from the others |