Chap. VIII.] OF NATUKAL SELECTION. 357 



as instinct alone is concerned, the wonderful difference 

 in this respect between the workers and the perfect 

 females, would have been better exemplified by the hive- 

 bee. If a working ant or other neuter insect had been 

 an ordinary animal, I should have unhesitatingly as- 

 sumed that all its characters had been slowly acquired 

 through natural selection; namely, by individuals having 

 been born with slight profitable modifications, which 

 were inherited by the offspring ; and that these again 

 varied and again were selected, and so onwards. But 

 with the working ant we have an insect differing greatly 

 from its parents, yet absolutely sterile ; so that it could 

 never have transmitted successively acquired modifica- 

 tions of structure or instinct to its progeny. It may 

 well be asked how is it possible to reconcile this case 

 with the theory of natural selection ? 



First, let it be remembered that we have innumerable 

 instances, both in our domestic productions and in those 

 in a state of nature, of all sorts of differences of inherited 

 structure which are correlated with certain ages, and 

 with either sex. We have differences correlated not 

 only with one sex, but with that short period when the 

 reproductive system is active, as in the nuptial plumage 

 of many birds, and in the hooked jaws of the male salmon. 

 We have even slight differences in the horns of different 

 breeds of cattle in relation to an artificially imperfect 

 state of the male sex ; for oxen of certain breeds have 

 longer horns than the oxen of other breeds, relatively to 

 the length of the horns in both the bulls and cows of 

 these same breeds. Hence I can see no great difficulty 

 in any character becoming correlated with the sterile 

 condition of certain members of insect-communities : 

 the difficulty lies in understanding how such correlated 



