INSTINCT 213 



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 structure which have become correlated to certain 

 ages, and to either sex. We have differences corre- 

 lated not only to one sex, but to that short period 

 alone 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 differ- 

 ences 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 

 in other breeds, in comparison with the horns of the 

 bulls or cows of these same breeds. Hence I can 

 see no real difficulty in any character having become 

 correlated with the sterile condition of certain mem- 

 bers of insect - communities : the difficulty lies in 

 understanding how such correlated modifications of 

 structure could have been slowly accumulated by 

 natural selection. 



This difficulty, though appearing insuperable, is 

 lessened, or, as I believe, disappears, when it is re- 

 membered that selection may be applied to the family, 

 as well as to the individual, and may thus gain the 

 desired end. Thus, a well - flavoured vegetable is 

 cooked, and the individual is destroyed ; but the 

 horticulturist sows seeds of the same stock, and 

 confidently expects to get nearly the same variety : 

 breeders of cattle wish the flesh and fat to be well 

 marbled together ; the animal has been slaughtered, 

 but the breeder goes with confidence to the same 

 family. I have such faith in the powers of selection, 

 that I do not doubt that a breed of cattle, always 

 yielding oxen with extraordinarily long horns, could 

 be slowly formed by carefully 'watching which indi- 

 vidual bulls and cows, when matched, produced oxen 

 with the longest horns ; and yet no one ox could ever 

 have propagated its kind. Thus I believe it has been 



