BUCKINGHAM. — DIVISION OF LABOR AMONG ANTS. 483 



12. Ji elation of Classes to Various Activities. 



From the foregoing account it is evident that, at least under the 

 conditions employed, both classes of Fheidole pilifera share in most 

 of the activities which were examined. In treatment of seed, no activ- 

 ity was shown by either class. The soldiers of this species took no 

 part in either feeding, tending the young, regurgitating, receiving 

 regurgitated food, licking, carrying or being carried ; but they were 

 more active than the minors in fighting. In being licked, the two 

 classes shared nearly ec^ually, but in all other activities the minors 

 excelled (feeding, regurgitating, licking, tending the young, building, 

 and carrying), occupations which may be called "household duties." 

 Carrying, in which the minors alone engaged, may be correlated with 

 the size of the head, for the body of a minor would be better balanced 

 when performing this duty than would that of a soldier. Guarding, 

 though shared apparently to a greater extent by the minors, seems to 

 be more or less accidental, and does not here consist — as in Colobopsis 

 and a species of Pheidole recorded by Reichenbach — of blocking the 

 entrances of the nests with the head. If it did, we should expect to 

 find always the same sort of worker at the same opening, which is not 

 the case in any of the species of Pheidole which I have studied. The 

 act of guarding seems here to be rather the result of the fact that, as 

 ants pass in and out, or are otherwise near an opening, they rush out 

 when disturbed. Now, the soldiers are not apt to leave the nest, and 

 hence are probably not as often near the openings, which would ac- 

 count for the greater number of minors found guarding. 



But if the minors are pre-eminently occupied with household duties, 

 the soldiers seem to be concerned with occupations requiring strength 

 of jaw, such as fighting, and though the minors help them in this, 

 there is much difference between the two classes in regard to this 

 activity. Moreover, when in the presence of the enemy, the soldiers 

 ran about snapping their jaws in a much more ferocious way than did 

 the minors, and they never ran away, whereas the minors frequently 

 did. We may, then, say that in this species the minors are, in gen- 

 eral, more concerned with "household duties," and the majors with 

 fighting, and, as Wheeler has shown, with crushing seed. 



ii. Studies of Pheidole pilifera in Barth Nests. 



1. Methods. — The methods here employed were exactly like those 

 described for Camponotus pictus (pp. 443 et seq., 46.5), except for the 

 difference in size of the nests. These nests were 5 inches in diameter, 



