BUCKINGHAM. — DIVISION OF LABOR AMONG ANTS. 445 



might naturally be expected in such an activity, were so recorded. 

 To gain as much evidence as possible from the observations, two meth- 

 ods of study were used, viz. (1) field notes, and (2) captured ants. 



1. Field Notes. — First, at the time the observations were made 

 notes were taken, giving general impressions of the sorts of individ- 

 uals engaged in various pursuits, and these notes were later carefully 

 summed up and compared for the different colonies. Although such 

 notes are necessarily in many respects less accurate for Camponotus, 

 because of the nature of polymorphism in the species here used, than 

 is the evidence derived from the second method, to be described below, 

 yet they reveal more precisely the numbers of ants engaged in the 

 various activities, and are, I think, in the main fairly correct. 



2. Captured Ants. — The second method employed in the field 

 work, used particularly in connection with Camponotus herculeanus 

 pictus, was as follows : Because the workers of this species form a 

 graded series (p. 438), it was in many cases impossible to judge with 

 accuracy as to the size of ants engaged in particular activities, and it 

 was, therefore, thought well to distinguish, for the purpose of later 

 study, those ants which shared in any given activity. Accordingly, 

 small vials of commercial alcohol were used, into each of which were 

 dropped all ants of a particular colony engaged in a given activity on 

 any day, and each bottle was provided with a label giving the colony, 

 the activity, and the date of capture of all ants contained therein. 

 For convenience each ant was later mounted on a separate pin with a 

 label containing the above data. 



D. Activities Tested. 



Although the activities of the ants studied have not all been tested 

 with each method of observation, some of them have. I give here the 

 whole category of activities which were examined by any method : 

 1. foraging, either («) presence in the field, or (b) actually carrying 

 food ; 2. partaking of different foods ; 3. feeding themselves ; 4. re- 

 gurgitating food to others, likewise receiving regurgitated food ; 5. 

 licking others, likewise being licked ; 6. tending the young (eggs, lar- 

 vae, or pupae) ; 7. building, (a) digging, (b) carrying earth; 8. carry- 

 ing other ants, likewise being carried by other ants ; 9. surrounding 

 the queen; 10. fighting; 11. responding to disturbances of the nest; 

 12. guarding ; 13. scavangering. 



Though the nature of most of these activities seems clear from the 

 names given them, a few, perhaps, need explanation. For example, 

 " preparing food " means tearing it into smaller pieces or crushing it 



