Figure 123. 
Weight and age differentials between pairs of males engaged in conflict situations. Arbitrary age class intervals for 
losers were selected. The straight lines connect the winners and the losers in each category. The curves represent the mean 
growth rate for all males in the pen. They are presented for the purpose of rapid comparison with the selected subgroups. 
Just below the point for the losers are two numerals. The first (not underlined) indicates the arbitrary age class interval of 
the losers,- see below. The second number (underlined) indicates the number of conflict situations, each involving two indi- 
viduals, from which the means of age and weight were determined. The two circled dots represent the means of all losers or 
all winners. 
Arbitrary age class intervals for losers: 
1 . Loser is the younger and under 1 50 days of age. 
2. Sibs of all ages. 
3. Loser is the older. 
A. 300-450 days of age. 
B. Over 600 days of age. 
but upon my return on November 15 it was empty. 
The earth about the base of the hopper had been 
scratched up in the rats’ efforts to glean the last 
morsel. There was fresh blood about the hopper 
and several spots of blood about the Food Pen. 
Similar spots of blood indicating intense fighting, 
was observed on another occasion after the food had 
become depleted. 
4. Loser is the younger. 
A. 1 50 to 250 days of age. 
B. 250 to 350 days of age. 
C. 350 to 450 days of age. 
In these instances there were two conditions, 
which contributed to the increased antagonism. 
They were hunger and competition over a limited 
supply of food. The following observation indi- 
cates that the latter of these two conditions was the 
more important one. During the nights of July 
10- 1 1 and 11 12, 1948, there was no food available 
to the rats in the Food Pen. Through these 2 nights 
192 
