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Show • 368 CLASSIFICATION. [CnAP. XIII. same stock, would have to be expressed by groups ~ubordinate to groups; but the proper ~r even only .possible arrangmnent would still be genealogical; and this would be strictly natural, as it would connect togethe~ ~11 lano- uao-es extinct and modern, by the closest affinities, and ~ou~d 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 .san1e with varieties as with species, na:mely, closeness of descent with various degrees of modification. Nearly the saine 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 Inost important part, happens to be nearly identical ; no one puts the swedish and common turnips together, though the esculent and thi~kened stems are so similar. Whatever part is found to be most constant, is used in classing varieties : thus the great aO'riculturist 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 apprehen9. if we bad a real pedigree, a genealogical classification would be universally P!eferred; 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 subvarieties differ from the others in the important character of having a longer beak, yet all are kept together from having the common habit of tumbling ; but the shortfaced breed has nearly or quite lost this habit; neverthe· 0BAP. XIII.] CLASSIFICATION. 369 less, without any reasonino- or thi 1 . th . these tumblers are 1 t · 0 h n nng on e subJect, . bl d d 1'1 . rep In t e smne group, because allied Ill oo an -a Ire In some other respects. If it could be pro~ed that the I-Iottentot had descended from the N eo-ro I think he would be classed under th N ho ' l h · 1 . . c egro group, ow-ever n1uc 1 e mig 1t d1fter in colour and th .. characters from negroes. 0 61 Important . With species in a state of nature, every naturalist has I·l l 1fa dc t b·r o1u g· ht descent into his class'fi t' . .(.' h 1 I ca Ion , 10r e .Inc u . es Idn 1n s ow est grade ' or that of a sp eC·i es, t. h e t wo sexes~ an lOW enormously. these sometimes differ in the most 1mpor~ant characters, IS known to every naturalist. scarcely a s1ngle fact c.an be predicated in common of th~ males and hcrn1aphrod1tes of certain cirri pedes when adult ~n~ yet no one drea1ns ?f separating them. The natural~ 1st Inc.lu~e~ as one speCies the several larval stages of the same Ind1v1dual, ho·wever much they may differ from each other and from the adult; as he likewise includes the so~ alled alte;nate generations of Steenstrup, which can onl 1n a. technical sense be considered as the same individuaL He Includes monsters ; he includes varieties, not solely because they resem?le the parent-form, but because they are descended from 1t. I-I~ who believes that the cowsiip is descended froi? the prn;uose, or conversely, ranks them together as a s1ngle speCies, and gives a single definition As soon as three Orchidean forms (Monochanthus, Myan: thus, and .C~tasetum), -which had previously been ranked as three d1stlnct genera, \vere known to be sometimes produced. on the sa~e spike, they were immediately included as a s1~g~e speCies. But it may be asked, what ought we to do, if It could be proved that one species of kangaroo ad been produced, by a long course of modification from a bear? Ought we to rank this one species with bears an~ ~ha~ should we do with the other species ? The sup: PhE\Itlon Is of course preposterous ; and I mio-ht answer by t e a~gumentum ad hominem, and ask what should be done 1f a perfect kangaroo were seen to come out of the womb of .a bear? According to all analogy, it would be ~f~ed k1th bears ; b'?-t then assuredly all the other species e angaroo family would have to be classed under 16* |
