BUCKINGHAM. — DIVISION OF LABOR AMONG ANTS. 475 



VI. Studies of Piieidole. 



A . Phe'idole pilifera. 



i. Experiments •with Ants in Aluminum Nests and Other Apparatus. 



1. Methods in General. 



I made use of four colonies of Phe'idole pilifera from Cambricl<^e, 

 Mass. In order to ascertain whether in these ants there is any corre- 

 lation between habits on the one hand and size and structure on the 

 other, an attempt was made, as with Camponotus americanus (pp. 44()- 

 465), to discover what proportion of each class (see pp. 438-440) took 

 part in each of several activities. 



In most cases I have endeavored to ascertain (a) the proportion of 

 the whole number of working ants which engage in a given activity, 

 and (b) the relation, if any, between the size of the individuals and the 

 sort of activities which they showed ; but in fighting, in carrying, and 

 in partaking of different kinds of food, I have considered only the sec- 

 ond of these two matters. 



All experiments, unless otherwise stated, were performed in alumi- 

 num nests ten inches long, six inches wide, and half an inch deep, kept 

 under the conditions described on pages 440-442, and in all cases both 

 chambers were exposed to daylight and ordinary room temperature 

 during observations. At other times the chamber not containing food 

 was darkened by a pasteboard cover and the nest was placed in the 

 heated chamber. 



2. Feeding Themselves. 



1. Methods. — To make sure that all the ants which partook of food 

 were observed, the food, on paraffined paper, was placed in the chamber 

 with the ants, the paper and the food being removed whenever the ants 

 were not under observation. To give the ants an environment as nat- 

 ural as possible, the chamber in which they lived was provided with 

 damp earth. During observations a record was made of the number 

 of ants of each class which partook of food during one hundred and 

 fifty periods of one minute each. 



2. Observations. — For convenience of comparison, the results of the 

 observations on the various activities of the several species are all placed 

 together in Table VII. Except for fighting, carrying, being carried, and 

 kinds of food, of which mention will be made in appropriate places, this 

 table was compiled as follows. The first column in the table gives the 

 number of the colony, and the first column under each activity shows the 

 number of observations made upon the colony concerning that activity. 



