26 ARE THE EFFECTS OF USE INHERITED? 



various respects. In many species of ants there 

 are two, and in the leaf-cutting ants of Brazil 

 there are three, kinds of neuters which differ from 

 each other and from their male and female 

 ancestors " to an almost incredible degree." l The 

 soldier caste is distinguished from the workers 

 by enormously large heads, very powerful man- 

 dibles, and " extraordinarily different " instincts. 

 In the driver ant of West Africa one kind 

 of neuter is three times the size of the other, 



1 Origin of Spe:ies, pp. 230-232 ; Bates's Naturalist on the 

 Amazons. Darwin is "surprised that no one has hitherto advanced 

 the demonstrative case of neuter insects, against the well-known 

 doctrine of inherited habit, as advanced by Lamarck." As he 

 justly observes, " it proves that with animals, as with plants, any 

 amount of modification may be effected by the accumulation of 

 numerous, slight, spontaneous variations, which are in any way 

 profitable, without exercise or habit having been brought into play. 

 For peculiar habits confined to the workers or sterile females, how- 

 ever long they might be followed, could not possibly affect the 

 males and fertile females, which alone leave any descendants." 

 Some slight modification of these remarks, however, may possibly 

 be needed to meet the case of "factitious queens," who (probably 

 through eating particles of the royal food) become capable of pro- 

 ducing a few male eggs. 



