Seite - 512 - in The Origin of Species

512 ORIGIN OF SPECIES absolutely perfect, as in the case even of the human eye; or if some of them be abhorrent to our ideas of fitness. We need not marvel at the sting of the bee, when used against an enemy, causing the bee's own death ; at drones being produced in such great numbers for one single act, and being then slaughtered by their sterile sisters ; at the astonishing waste of pollen by our fir-trees ; at the instinctive hatred o£ the queen-bee for her own fertile daughters; at ichneumon- idae feeding within the living bodies of caterpillars; or at other such cases. The wonder indeed is, on the theory of natural selection^ that more cases of the want of absolute perfection have not been detected. The complex and little known laws governing the produc- tion of varieties are the same, as far as we can judge, with the laws which have governed the production of distinct species. In both cases physical conditions seem to have pro- duced some direct and definite effect, but how much we can- not say. Thus, when varieties enter any new station, they occasionally assume some of the characters proper to the species of that station. With both varieties and species, use and disuse seem to have produced a considerable effect; for it is impossible to resist this conclusion when we look, for instance, at the logger-headed duck, which has wings in- capable of flight, in nearly the same condition as in the do- mestic duck; or when we look at the burrowing tucu-tucu, which is occasionally blind, and then at certain moles, which are habitually blind and have their eyes covered with skin; or when we look at the blind animals inhabiting the dark caves of America and Europe. With varieties and species, correlated variation seems to have played an important part, so that when one part has been modified other parts have been necessarily modified. With both varieties and species, reversions to long-lost characters occasionally occur. How inexplicable on the theory of creation is the occasional ap- pearance of stripes on the shoulders and legs of the several species of the horse-genus and of their hybrids ! How simply is this fact explained if we believe that these species are all descended from a striped progenitor, in the same manner as the several domestic breeds of the pigeon are descended from the blue and barred rock-pigeon !