WHAT IS DARWINISM? 35 



of the ant, which he finds very hard to account 

 for. He adds, " No doubt many instincts of 

 very difficult explanation could be opposed to 

 the theory of natural selection : cases in which 

 we cannot see how an instinct could possibly 

 have originated ; cases in which no interme- 

 diate gradations are known to exist ; cases of 

 instinct of such trifling importance that they 

 could hardly have been acted upon by natural 

 selection ; cases of instincts 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 pro- 

 genitor, and consequently cannot believe that 

 they were independently acquired through nat- 

 ural selection. I will not here enter on those 

 cases, but will confine myself to one special 

 difficulty which at first appeared to me insu- 

 perable, and actually fatal to the whole theory. 

 I allude to neuters, or sterile females in insect 

 communities ; for these neuters often differ 

 widely in instinct and structure from both the 

 males and the fertile females, and yet, from 

 being sterile, they cannot propagate their 

 kind." (p. 289) He is candid enough to say, 

 in conclusion, "I do not pretend that the facts 

 given in this chapter (on instinct) strengthen 



