82 Bulletin American Museum of Natural History. [Vol. XXII, 



through the entrance when the female became suddenly much interested in 

 the brood. She killed 2 workers in quick succession and began to collect the 

 pupae in the light (previously dark) chamber and tried to conceal them, at first 

 in the entrance and then in one of the corners which I darkened for her. The 

 pupae in this chamber were at first much scattered, but the female had collected 

 all of them by 8.40 a. m. Meanwhile one worker kept stealing into the chamber 

 and making off with some of the pupae into the dark chamber. At 9 a. m. the 

 female caught one of the workers in flagrante delicto and nearly killed her with 

 a blow of her mandibles. She released the worker and went to look after the 

 pupas. Later, on passing, she noticed that the worker was still moving and 

 dispatched her. By 9.10 the female had collected all but 2 of the pupae, 37 in 

 number, and was carefully guarding them at 12 m. July 19, 7.30 a.m., she 

 was surprised in the act of removing the pupal skin from the limbs of a hatching 

 callow. She was still very alert and pugnacious and during the night had evi- 

 dently successfully protected the pupae from all incursions of the suhsericea 

 workers in the adjoining chamber. Another callow hatched at 4 p. m., July 20. 

 Matters were in statu quo except that a third callow had made its appearance 

 during the night. The female was not molested by the suhsericea workers, that 

 remained in their own chamber after plugging up the entrance with pellets of 

 earth. At 6.30 p. m. the female had 7 callows and by 7.30 a. m. on the following 

 morning an eighth had made its appearance. Matters remained in statu quo 

 during the two following days, when the female was released in the garden. 



Experiment 40. July 19, 8 a.m. Two ruhicunda sisters, A and B, distin- 

 guished by a difference in size, were placed in a nest containing 6 mature, me- 

 dium-sized suhsericea workers, 12 callows two days old but able to run about 

 and carry pupae, and about 125 nude pupae, all with pigmented eyes and some 

 of them brown and nearly ready to hatch. The workers at once fled with their 

 brood. Female A began to prance about as soon as her antennae had explored 

 the fine assortment of pupae. She went from one worker to another pinching and 

 when necessary killing them. Even the young callows tried to defend them- 

 selves and their brood, but were soon (8.15 a. m.) driven to the other end of the 

 nest. A at once began to move the pupas into a corner. B was less excitable 

 and very listless ; she at first tried to escape from the nest by biting at the towel- 

 ling; then she dug a hole in the earth, and finally took to carrying pellets of 

 earth, dead suhsericea workers, etc., for short distances in a desultory manner. 

 At last, however, she joined A in defending the pupae and even tweaked the 

 workers when they ventured into her neighborhood. Both of the females 

 seemed to be very lenient with the callows and seriously injured only 2 of them, 

 while they killed 4 of the mature workers outright. The workers, however, 

 succeeded in recovering about a dozen of their pupae. Female B now set about 

 collecting the young callows and carrying them to the pile of pupas, and then 

 began to take the pups away from the workers at the farther end of the nest. 

 By 8.30 both females were equally excited and busy and working in unison. 

 The two opposite ends of the chamber were darkened and the middle portion 

 exposed to the light for the purpose of ascertaining whether the females would 

 establish separate nests. 11 a.m. With the exception of the two youngest 

 callows, every suhsericea in the nest had been killed and their bodies had been 

 placed by the females at one end of the nest, while they had collected all the 

 pupae and the two young callows in a single pile at the other end. Both females 



