BUCKINGHAM. — DIVISON OF LABOR AMONG ANTS. 4G5 



when examined in the field (pp. 407-471). There seems here to be a 

 greater activity on the part of some individuals than of others, irre- 

 spective of size ; this is probably due to psychological dififerences of 

 individuals, as suggested by Escherich (:06, p. 45). But there seems 

 also to be some evidence of a division of labor correlated with polymor- 

 phism ; this is not marked by hard and fast lines, since all classes may 

 share in any activity, but by a preponderance (a) of large ants in fight- 

 ing, (h) of those of medium and small size in building, (c) of those 

 of small size in tending the young, and (d) of those of small and me- 

 dium size in foraging. 



7. The small and medium-sized workers are, in general, much more 

 active than the largest ones. 



B. Camponotus herculeanus pictus, 

 i. In Barth Nests. 



1. Methods. — In Barth nests, 8 inches high X 6 inches in diam- 

 eter, with f inch between the jars, five colonies of C. herculeanus pictus 

 were studied, all of which had been previously studied in the field, the 

 object being to compare the two sets of studies with a view to learning 

 if the ants behaved differently in the laboratory from what they did in 

 the field. In other words, the field studies afforded a control for those 

 in the laboratory. Therefore, not only those activities which had been 

 unsatisfactorily examined in the field were studied, but also all others. 

 The colonies were necessarily smaller than those in the natural nests, 

 as it was impossible to collect the whole of a colony. I attribute to 

 this diminution of the size of the colony the fact that, as a whole, the 

 ants in captivity were less active than those in the field, for it will later 

 be seen (p. 471) that in the normal state the smaller colonies of Cam- 

 ponotus herculeanus pictus were less active than the larger. 



2. Observations. — In the Barth nests I have never seen any of these 

 ants carrying in food, feeding themselves, or preparing food. More of 

 the intermediate sizes than of any other size were seen outside of the 

 earth at the top of the nest, or running about in the bottom of the 

 well, i. e. the inside jar, a condition which may be compared to for- 

 aging. The other two sizes about equalled each other in this activity. 



In regurgitating and receiving regurgitated food it is difficult to 

 see in which direction the food passes. But as I have seen this process 

 occur between all possible combinations of majors, intermediates, and 

 minors, no one class can be the sole regurgitators ; I rather suspect 

 that it is more common for the two smaller classes to regurgitate, and 

 for the majors to receive. The reasons are as follows : First, the 



VOL. XLVI. — 30 



