Dariviiis Theory of Sexual Selection 179 



gives a graphic account of the agile way in which the dimin- 

 utive male escapes from the ferocity of the female, by gliding 

 about and playing hide and seek over her body and along her 

 gigantic limbs : in such a pursuit it is evident that the 

 chances of escape would be in favor of the smallest males, 

 while the larger ones would fall early victims ; thus gradually 

 a diminutive race of males would be selected, until at last 

 they would dwindle to the smallest possible size compatible 

 with the exercise of their generative functions, — in fact 

 probably to the size we now see them, i.e. so small as to be 

 a sort of parasite upon the female, and either beneath her 

 notice, or too agile and too small for her to catch without 

 great difficulty.' " 



It is certainly surprising to find Darwin ascribing even 

 this difference in size between the sexes to the action of 

 selection. Is it not a little ludicrous to suppose that the 

 females have reduced the males to a size too small for them 

 to catch ? 



There are many cases known in the animal kingdom where 

 there is a difference in size between the two sexes, especially 

 in the group of insects ; but I doubt very much if they are to 

 be accounted for as the result of sexual selection. In some 

 of these cases Darwin accounts for the larger size of the 

 female, on account of the large number of eggs which she 

 has to carry. In other insects where the male is larger, 

 as in the stag-beetle, the size is ascribed to the conflicts of 

 the males, leading to the survival of the larger individuals. 

 In still other cases, where the males are larger, but do not 

 fight, an explanation is admittedly wanting; but it is suggested 

 that here there would be no necessity for the males to be 

 smaller than the females in order to mature before them (as 

 is supposed to happen in other species), for in these cases 

 the individuals are not short-lived, and there would be ample 

 time for pairing. Again, although the males of nearly all 

 bees are smaller than the females, yet the reverse is true in 



