322 
Psyche 
[Vol. 91 
Results 
The biological half life of 125 I-albumin in workers, queens, and 
larvae is shown in Fig. 1. Without any additional labeled food 
entering the colony, the level of radioactivity in queens and larvae 
dropped below 50% by the third day and remained at 40% and 1 1%, 
respectively. The level of radioactivity in the workers stabilized at 
65-70% after four days. This pattern was seen in all of the 
treatments, regardless of which subcastes were present. By super- 
imposing this background pattern on those obtained when labeled 
food was allowed to enter the colony freely, we were able to estimate 
the amount of additional food distributed. 
The relationship between total amount of food collected per 
colony and the partitioning of that food among subcaste members is 
illustrated in Figure 2. The daily amount of food collected per ant 
was regressed against the daily total of food collected by the colony. 
As the quantity of proteinaceous food in the colony increased, the 
rate at which the queen accumulated food was significantly higher 
than that of the larvae, reserves, nurses, and foragers. The rates at 
which larvae and reserves received food were significantly higher 
than that of the nurses and foragers. 
A summary of the mean amount of food brought in by each 
colony over a one week period is shown in Figure 3. Three different 
colonies (A, B, and C) were used in the treatment groups and five 
other colonies used in the control groups. There were significant 
differences in the quantity of food collected by foragers, nurses, or 
reserves held by themselves. With nurses, a time delay of 3 days 
occurred before foraging was initiated. Paired worker subcastes also 
showed some variability in foraging activity. Overall, groups of 
foragers alone collected significantly more food than groups 
without foragers present with the exception of one R/N trial. The 
food collected by a mixture of all 3 subcastes was similar to that 
collected by R/N combinations or groups of nurses or reserves by 
themselves. There was, however, considerable variation in mean 
protein collected. Ants from colony C collected more food than ants 
from either colony A or B in most cases and ants from colony B 
collected less food in most cases. 
Table 1 presents a summary of least square means (ug protein/ 
ant) using the total food per colony as a covariate. This minimizes 
the effect that quantity of food in the colony has on the food 
