92 Darwin, and after Darwin, 



observation. Nevertheless, I do not question that 

 there are instinctive activities which, as far as we are 

 able to see, can never have been performed more 

 than once in each individual life- time 1 . The fact, 

 however, only goes to show what is fully admitted 

 that some instincts (and even highly complex instincts) 

 have apparently been developed by natural selection 

 alone. Which, of course, is not equivalent to showing 

 that all instincts must have been developed by natural 

 selection alone. The issue is not to be debated on 

 general grounds like this, but on those of particular 

 cases. Even if it were satisfactorily proved that the 

 instincts of a queen-bee have been developed by 

 natural selection, it would not thereby be proved 

 that such has been the case with the instincts of 

 a Sphex wasp. One can very well understand how 

 the nuptial flight of the former, with all its associated 

 actions, may have been brought about by natural 

 selection alone ; but this does not help us to under- 

 stand how the peculiar instincts of the latter can have 

 been thus caused. 



Strong evidence in favour of Weismann's views 

 does, however, at first sight seem to be furnished by 

 social hymenoptera in other respects. For not only 

 does the queen present highly specialized and alto- 

 gether remarkable instincts ; but the neuters present 

 totally different and even still more remarkable 

 instincts which, moreover, are often divided into 

 two or more classes, corresponding with the different 

 " castes." Yet the neuters, being barren females, 

 never have an opportunity of bequeathing their 

 instincts to progeny. Thus it appears necessary to 



1 See Mental Evolution in Animals, pp. 377-8. 



