96 
Psyche 
[March-June 
heavy-fed group r = 0.9m; both correlations are significant at 
the 0.1% level. In most instances those animals with the extreme 
weights at the beginning of feeding remained the extremes in their 
group. Reasons for the variation in initial weight are unknown. 
Different rates of growth for light and heavy hatchlings have re- 
cently been shown to occur in several species of spiders, apparently 
independent of food available, and appear correlated with different 
lengths of life (Reed and Witt, 1972). 
AMOUNT EATEN : An approximation of the amount eaten was ob- 
tained for a three week period. For nine heavy-fed animals the 
mean amount eaten during the three week period was 115.8 mg and 
for fifteen light-fed animals the mean amount for the same period 
was 35.O mg. Within each group, however, there was an enormous 
variation in the amount consumed : in the heavy-fed group the 
amount eaten by individual animals ranged from 209.0 mg to 42.6 
mg while in the light-fed group the amount eaten ranged from 
49.6 mg to 3 gnats weighing 18 mg. 
feeding and web changes: Table i gives a summary of web 
changes that accompanied the growth of the animals. In measure- 
ments of web size both groups increased, with the heavy-fed group 
having a much larger increase as illustrated in Figure 2. In measure- 
ments of web regularity both heavy-fed and light-fed groups re- 
mained constant, as shown in figures of Table 1. 
Discussion 
The observed differential growth and development in Araneus 
diadematus seems to be a function of several factors. Although an 
exposure to a greater than normal supply of food generally results 
in faster than normal growth and development, even within a group 
exposed to the same food supply there seems to be a great variation 
in growth rates. Evidence of these differences is expressed in the 
increasing standard errors in Figure 1, and seems to be dependent 
upon individual factors in the animals rather than environmental 
variations. Large differences in the amount eaten by individual 
animals in the laboratory existed and presumably exist in nature. 
These differences seem to correspond to differences in the rate of 
growth in agreement with the findings of Turnbull in other species 
of spiders (Turnbull, i960, 1965). However, whether these dif- 
ferences in the amount of food eaten are due to differences in pro- 
ficiency in prey-catching or to differences in appetite or some other 
factor in the animal is not clarified by our findings. 
