BUCKINGHAM. — DIVISION OF L.VBOR AMONG ANTS. 481 



nest, and if so, to which class or classes they belonged, the entrances 

 to the nest were probed with a bristle either once every five minutes 

 (colony 81) or once every minute (colonies 86, 87, 91). 'J'he number 

 of ants of each class emerging from these entrances at each observation 

 was recorded. Often the first individual to come from the entrance 

 attacked the bristle with widely opened jaws, in some instances even 

 clinging to the bristle. Sometimes, however, it rushed out excitedly, 

 with open jaws, and then hurried back into the hole, whence it often 

 emerged again, sometimes followed almost immediately by one or more 

 other ants. In such cases the class to which these accompanying ants 

 belonged was also recorded, though they were not considered as be- 

 longing among the original guards. 



2. Observations . — Four colonies of Pheidole pili/era were experi- 

 mented on by making one hundred and fifty observations on colony 81, 

 and one hundred observations on each of colonies 86, 87, and 91. 



Only a very small per cent (0 ; 0.2 ; 0.1; 0.3 respectively) were en- 

 gaged in this activity, one colony giving no response ; moreover, the 

 number was not correlated with the whole number of ants in the 

 colony. 



In two of the responsive colonies (86 and 87) of this species, the 

 soldiers were not represented ; in the other they were slightly more 

 active than the minors (0.2 >0.03) ; but we may say of this species 

 that on the whole the minors were the more active. 



9. Fighting. 



1. Methods. — In this activity it was impossible to deal with per 

 cents of the colony as a whole, because when an enemy was introduced, 

 all the ants of the colony rushed about in such a lively and excited 

 manner that it was out of the question to count even those which at- 

 tacked it. Accordingly the soldiers of the colony were placed, in a 

 Stender dish, 5.5 cm. in diameter, and an equal number of minors were 

 placed in another Stender dish of the same size. If a minor was killed, 

 another was put in its place, but if a soldier was killed, the number of 

 minors was reduced by removing one of the minors, so that the number 

 of ants in the two dishes was constantly equal. The observations con- 

 sisted in counting for one-minute periods the number of ants clinging 

 to an enemy which was placed for that length of time alternately with 

 the soldiers and with the minors. The enemy introduced was an ant 

 from a colony of Camponotus americanus. 



2. Observations. — Fifty observations were made on each of two colo- 

 nies of Pheidole pilifera (colonies 86 and 87). Under "Fighting," 

 and " Carrying and Being Carried," in Table VII the first column gives 



VOL. XLVI. — 31 



