350 CLASSIFICATION. 



resembling, or differing from, each other. Among these, some 

 are so essentially alike, that we involuntarily apply to them the 

 same name. A field of Wheat is filled with similar individuals, 

 which we can separate, but cannot distinguish. Or, although it 

 be possible to distinguish separate individuals, from any peculiarity 

 of size, &c., we still inevitably associate them, as being much 

 more like each other than like any surrounding forms, so like, 

 that we view the difference as an accidental circumstance. Fur- 

 thermore, the Wheat tillers, that is, branches from the ground, 

 and shoots forth a number of stalks from the same root, stalks 

 which are separable, or separate spontaneously, from the primary 

 one. So, also, the branches of trees, which may grow indefinitely 

 as a part of an original tree (148), become, when detached and 

 planted by themselves in the soil, independent, but perfectly similar 

 individuals (167, 229). Probably all the Weeping W r illows, or 

 Lombardy Poplars, of this country have sprung in this way from a 

 single shoot. The grain of wheat, also, will reproduce similar 

 individuals, and none other. Now, upon such universal and inev- 

 itable conceptions as these rests the idea of 



667. Species, We mentally assemble, under this name, those 

 individuals which we observe or judge to have arisen from one 

 parent stock, or which, although met with widely dissociated, re- 

 semble each other so closely that we infer them to have had a 

 common parentage. A SPECIES we have already defined (14) to 

 be, abstractly, the type or original of each sort of plant, or animal, 

 thus represented in time by a perennial succession of like individ- 

 uals, or, concretely, the sum of such individuals. It embraces all 

 those individuals which, slightly differing, perhaps, in size, color, or 

 such unimportant respects, resemble each other more nearly than 

 they resemble any other plants, so that we infer them to have 

 sprung from a common original stock, and which preserve their 

 characters unchanged when propagated by seed. All classifica- 

 tion and system in natural history rest upon the fundamental idea 

 of the original creation of certain forms, which have naturally been 

 perpetuated unchanged, or with such changes only as we may 

 conceive or prove to have arisen from varying physical influences, 

 accidental circumstances, or from cultivation. Whether the origi- 

 nal stock consisted of one individual or pair, or of numerous indi- 

 viduals, is not material to the view. (On the latter supposition, 

 however, we can readily perceive that certain varieties or races 

 may have been aboriginal.) 



