BUCKINGHAM. — DIVISION OF LABOR AMONG ANTS. 4G9 



either morphologically or physiologically, and therefore, all that one 

 can say is that ants of certain sizes predominate in a given activity. 



Another very striking conclusion which may be drawn from the field 

 notes is that on the whole the majors are relatively inactive in all oc- 

 cupations except fighting, while the other two sizes taken together are 

 very active. Only a small proportion of the colony is at one time oc- 

 cupied in any given activity. 



2. Captured Ants. 



1. MetJiods. — Ants of twenty-two colonies of Camponotus hercii- 

 leanus pictus were studied in their natural out-door nests, as described 

 on pages 467-4(39. When insects from the same nests had been killed, 

 they were, as mounted specimens, arranged in series according to size, 

 and a permanent record of each series was secured by means of pho- 

 tographs showing the insects ' natural size. This was done to show 

 particular facts given below. One series consisted of ants engaged 

 in foraging {a, all the ants seen in the field ; b, ants seen carrying 

 food in the field) ; a second, tending the young ; a third, building 

 (a, carrying earth ; h, digging ; c, digging under excitement) ; a 

 fourth, surrounding the queen ; a fifth, carrying other ants ; a sixth, 

 being carried by other ants ; a seventh, fighting, i. e. rushing out when 

 the nest was disturbed, or running about excitedly five minutes after 

 the nest had been disturbed. In order to compare the various colonies 

 studied for each activity, the ants of each colony engaged in a given 

 activity were arranged by themselves, according to size, from the small- 

 est to the largest. Other series were also made, where no attention 

 was paid to colonies, all the ants taking part in each occupation being 

 arranged in a single series. 



2. Observations. — In the case of each occupation it was found that 

 there was a perfectly graded series of sizes, i. e. with no division into 

 classes ; this means that all sizes take part in each activity which was 

 tested. This was especially marked when all the colonies were ar- 

 ranged in a single series. 



But when the various occupations were compared with one another, 

 it was found that, although ants of various sizes shared in each activity, 

 in some activities there is much more of a tendency for the large ants 

 to take part, while the smaller ants are more inclined to share in 

 other activities. The smaller ants, for example, are much more apt 

 to tend the young, while the larger ones are more prone to rush out 

 when the nest is disturbed. Thus, I was able to group the series rep- 

 resenting the several activities in such a way that the series in which 

 the small ants predominated were at one end, and those in which the 



