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 ! 



