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



day (July 12), when six inore artificially dealated consocians females were in- 

 troduced, making a total of nine in the nest. The six new females were all 

 placed in the light chamber, but as soon as they could find the opening they 

 entered, crossed the dark chamber and at once ascended the pile of cocoons 

 where the incerta workers were brooding. There was a little rather half-hearted 

 resistance on the part of the incerta, but after a few moments all nine females 

 were peaceably elbowing each other on the brood-pile while they cleaned one 

 another and the incerta and fed and received food from the latter. At 7 p. m., 

 however, two of the females engaged in a fierce combat, while all the others 

 remained undisturbed. One of the pair escaped, whereupon the victorious in- 

 dividual went up to another female and began to pick a quarrel with her. 

 In these combats one of the females always tried to bite through the other's 

 thorax. July 13, 8 a.m. two of the females were dead, but one of them had 

 evidently died from an injury received while she was being placed in the nest. 

 The remaining 7 females were to all appearances living in perfect amity, with 

 the incerta and with one another. At 12 m. three dealated and three winged 

 females were introduced, making a total of 13. No hostilities were observed 

 during the remainder of the day. July 15. One dealated female died during 

 the course of the morning. The three winged females sought the light chamber, 

 where they huddled side by side on the lower surface of the roof-pane. They 

 showed no interest in the incerta or in their dealated sisters. From July 16 to 

 26 no hostilities were observed. The dozen females had been adopted by the 

 incerta and had settled their differences with one another. The winged females 

 retained all their wings and exhibited the behavior peculiar to their sex before 

 deflation, till July 26, when I had to close the experiment. The females used 

 in this experiment were taken from two widely separated wild colonies. 



These experiments disclose several interesting facts: 

 First, it is clear that, though the introduced consocians females are 

 recognized as aliens, they nevertheless often succeed in overcoming 

 the hostile instincts of the incerta and acquiring adoption. When 

 consocians females are persistently kept before the incerta, the latter 

 become reconciled to their presence and will tolerate a considerable 

 number of them in the nest. 



Second, there is a pronounced tendency for the females to war on 

 one another. These struggles are much fiercer than those between 

 the consocians and the incerta. This fact is surprising because the 

 females used in the above experiments were usually taken from the 

 same colony and had been amicably snuggling together as daughters 

 of the same mother before they were introduced to the incerta. I am 

 inclined to believe that this mutual hostility of the females is a useful 

 adaptation to prevent, as it must in a state of nature, the over-peopling 

 of an incerta nest with these parasites. If this is the case it is 

 perhaps difficult to understand why the hostility subsides and even 

 ceases altogether when the number of females in an incerta colony is 



