66 GENERAL ZOOLOGY 



exposed to the weather. As soon as one cell is finished the 

 female lays an egg in it, and to her duty of enlarging and 

 strengthening the nest she soon lias to add the care of the 

 footless, worm-like larvae, which hatch in a few days. These 

 are fed with both plant and animal food, the former consist- 

 ing of nectar which has been swallowed and later regurgitated 

 (i.e. thrown back after being swallowed) ; the latter, of cater- 

 pillar meat chopped fine by the mandibles and worked into 

 a jelly-like mass. In about three weeks' time the first-born 

 larvae spin a silken lining and covering to the cell and pass 

 into an inactive pnpal stage. Three weeks later the first 

 imagoes appear, after having cut a circular opening in the 

 end of the cell. 



These first imagoes differ somewhat from their mother, 

 and are really imperfectly developed females, called neuters, 

 or workers. They have the power, under certain conditions, 

 of laying eggs, but their eggs never produce true females. 

 Generally the workers attend strictly to the business of caring 

 for the young and repairing and enlarging the nest. They 

 assume care of the young at about the third day. 



This habit may be due primarily to imitation of the female, 

 whom the worker sees repeating the act while it is waiting 

 for the hardening of its tissues, or to the early development 

 of an instinctive tendency to perform the act (see p. 85). 

 Experiments performed by Dr. Enteman of the University 

 of Chicago, in which newly developed workers were given 

 bits of food at intervals before they had had any association 

 with others of their kind, seem to show that it is an instinct 

 which appears very early, but not at the same time with 

 all workers. When it does appear, owing to the presence of 

 food furnished by the female, the steps are, according to 

 Dr. Enteman, " first the crushing and molding, then a slow 

 walking around the nest with frequent pauses, and, if larvae 

 are present, the pinching off of the food bit by bit until all 



