86 THE STUDY OF ANIMAL LIFE CHAP. 



A caste of workers (i.e. normally non-reproductive 

 females) distinct from the males and queens, involves, of 

 course, some division of labour ; but there is more than 

 this. Workers of different ages perform different tasks 

 foraging or housekeeping, fighting or nursing, as the 

 case may be ; and the division of labour is associated 

 with differences of structure. Thus, in the Saiiba or 

 Umbrella Ant of Brazil (OEcodoma cephalotes), so well 

 described by Bates in his Naturalist on the Amazons, 

 there are three classes of workers. All the destructive 

 labour of cutting sixpence-like disks from the leaves of 

 trees is done by individuals with small heads, while others 

 with enormously large heads simply walk about looking 

 on. These " worker-majors ' are not soldiers, nor is 

 there any need for supervising officers. " I think," Bates 

 says, " they serve, in some sort, as passive instruments 

 of protection to the real workers. Their enormously 

 large, hard, and indestructible heads may be of use in 

 protecting them against the attacks of insectivorous 

 animals. They would be, on this view, a kind of pieces 

 de resistance., serving as a foil against onslaughts made 

 on the main body of workers." The third order of 

 workers includes very strange fellows, with the same 

 kind of head as the worker-majors have, but " the front 

 is clothed with hairs instead of being polished, and they 

 have in the middle of the forehead a twin simple eye," 

 which none of the others possess. Among the honey 

 ants (Myrmecocystus mexicanus) described by Dr. M'Cook 

 from the " Garden of the Gods ' in Colorado, the divi- 

 sion of labour is almost like a joke. The workers gather 

 1 honey ' from certain galls, and discharge their spoils 

 into the mouths of some of their stay-at-home fellows. 

 These passive " honey-pots " store it up, till the abdomen 

 becomes tense and round like a grape, but eventually 

 they have even more tantalisingly to disgorge it for other 

 members of the community. But this habit of feeding 

 others is exhibited, as Forel has shown, by many species 

 of ants. The hungry apply to the full for food, and get 

 it. A refusal is said to be sometimes punished by death ! 



Marvellous in peace, the ants may also practise the 



