496 PROCEEDINGS OF THE AMERICAN ACADEMY. 



:04'' ; :05^ p. 5), the group of which Formica rufa is the centre (Wheeler, 

 : 05''), or Polyergus (Wheeler, : 05^ p. 3), — where the queen cannot 

 bring up her first brood, but must depend for that on ants of another 

 species, — the queens would not have been found engaged in any work ; 

 but Wheeler (:08% p. 65) makes the statement that even queens which 

 cannot bring up their first brood show threptie instincts. The essen- 

 tial role of the queen, however, even in Camponotus herculeanus pictus 

 and G. americanus, seems to be egg-laying rather than attending to 

 any other duties, and she is, in consequence, rather passive, and is 

 never found outside the nest except at the time of swarming. I had 

 no opportunity to study the queen of Pheidole pilifera, for I have 

 never seen a queen of this species outside the nest, and only once found 

 one in the ground. They seem to be very timid and shy, and I have 

 no reason to think that they take an active part in the work of the 

 nest, even though, according to Wheeler (: 02, p. 768), they can found 

 their own colonies. 



7. In regard to the class or classes which do most of the work, it is 

 noticeable that in both species of Camponotus the two smaller classes, 

 and in all the species of Pheidole studied the small workers, predomi- 

 nated in all the " household duties " and in foraging. Furthermore, 

 they move with greater rapidity and seem in every way much more 

 lively, except when a fight occurs. On the other hand, the large workers 

 in both genera were relatively sluggish. When the nature of polymor- 

 phism is considered, this seems to be most reasonable, for the large 

 workers, especially in Camponotus, are much more like the queen in 

 structure than are the small workers. Pricer (: 08) has recently shown 

 that in Camponotus, at any rate, the large workers make their appear- 

 ance in a colony only slightly before the sexual forms, while the small 

 workers appear as the first brood, and Wheeler (: 02) several years ago 

 stated the same fact for Pheidole. As soon as this first brood has 

 reached maturity, the queen gives over all the work to them, and there- 

 after is even less active than the largest workers. But when a colony 

 has reached sufiicient size to produce large workers, there are more 

 individuals than are needed to carry on the work, and the large indi- 

 viduals, being less well adapted for the various occupations, come to 

 take on not only the queen's duties, some of them laying eggs, but also 

 .approach her in instinct, becoming less employed than the smaller 

 workers. We have already seen that it is especially in times of danger 

 that the queen's instinct to work returns to her (Escherich, : 06, p. 45 ; 

 Wheeler, : 05", p. 271), and that she then becomes more active; or, if 

 a queen is deprived of her first brood (Wheeler, : 06'» ; : 10, p. 527), she 

 begins to bring up another brood, precisely as in the first instance, pro- 



