226 OBJECTIONS TO THE THEOICY CriAP. VII. 



be 0])poscJ to tlic theory of natunil selection — cases, in -which 

 Ave cannot sec how an instinct could ])ossibly liave originated; 

 cases, in ■which no intermediate gradations arc known to exist ; 

 cases of instinct of such trifling importance, that they could 

 hardly have been acted on by natural selection ; cases of in- 

 stincts almost identically the same in animals so remote in the 

 scale of Nature, that we cannot account for their similarity by 

 inheritance from a common progenitor, and consequently must 

 believe that they were independently acciuircd through natural 

 selection. I will not here enter on these several cases, but 

 will confine myself to one special difficulty, which at first ap- 

 jieared to me insuperable, and actuall}' fatal to the whole 

 theory. I allude to the neuters or sterile females in insect- 

 communities : for these neuters often differ widely in instinct 

 and in structure from both the males and fertile females, and 

 yet, from being sterile, they cannot propagate their kind. 



The subject well deserves to be discussed at great length, 

 but I Avill here take only a single case, that of working or 

 sterile ants. Hoav the workers have been rendered sterile is a 

 difriculty : but not much greater than that of any other strik- 

 ing modification of structure ; for it can be shown that some 

 insects and other articulate animals in a state of nature occa- 

 sionally become sterile ; and if such insects had been social, 

 and it had been profitable to the community that a numl^er 

 should have been annually born capable of work, but incapable 

 of procreation, I can see no especial difficulty in this having 

 been efT(M'ted through natural selection. But I must pass over 

 this preliminary difficulty. The great difiiculty lies in the 

 working ants differing widely from both the males and the 

 fertile females in structure, as in the shape of the thorax, and 

 in being destitute of wings and sometimes of eyes, and in in- 

 stinct. As far as instinct alone is concerned, the Avonderful 

 difference in this respect between the Avorkers 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, 1 should have mihesitatingly assumed that all its char- 

 acters 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 onward. 

 But with the Avorking ant we have an insect differing greatly 

 from its parents, yet. absolutely sterile ; so that it could never 

 have transmitted successively-acquired modifications of struct- 



