Hence every genus requires different species, and these subspecies, and since none of the latter once again is ever without a sphere, (adomain as a conceptus communis),' reason demands in its entire extension that no species be re garded as in itself the lowest; for since each species is always a concept that contains within itself only what is common to different things, this concept cannot be thoroughly determined, hence it cannot be related to an individual, consequently, it must at every time contain other concepts,.e., subspecies, under itself.