276 
Psyche 
[Vol. 91 
Table 2. Comparison of spring and summer fecundity parameters by ANCOVA. 
* = p< .05; ** = p< .01. 
Number of Eggs in First Sac 
Source 
D.F. 
M.S. 
F 
Equality of Adj. Means 
1 
295 
.82 
Zero Slope 
2 
2305 
6.45** 
Error 
79 
357 
Equality of Slopes 
2 
730 
2.10 
Error 
77 
348 
Adjusted Means (± s.e.)— ^ 
Spring: 61 ±3 
Summer: 56 ± 4 
Egg Diameter (mm). First Sac 
Source 
D.F. 
M.S. 
F 
Equality of Adj. Means 
1 
152.6 
11.13** 
Zero Slope 
1 
56.2 
4.10* 
Error 
87 
13.7 
Equality of Slopes 
1 
4.8 
.34 
Error 
86 
13.8 
Adjusted Means (± s.e.) — 
Spring: .606 ± .006 
Summer: .638 ± .007 
number of immatures occupying all eight units was slightly over 100 
(Fig. 4). All appeared to be younger than the penultimate instar, 
judging from the absence of significant swelling of male palps and 
the undeveloped female external genitalia. During the experiment 
39 very small juveniles were removed from the populations. These 
spiders were obvious immigrants, most likely the progeny of 
summer-maturing adults. The disappearance of immature spiders 
during August coincided with the appearance of adult males and 
females (Fig. 4). The rate of appearance of mature spiders of both 
sexes declined in September; no mature males appeared on the units 
after 1 September. 
Supplementing the food supply did not affect numbers of imma- 
ture or mature spiders on the units, nor did providing additional 
prey influence size at maturity. During the experiment mean 
numbers per unit and linear dimensions of removed adults were 
practically identical for the supplemented and control populations. 
Only 36 ± 2% of the spiders accepted the additional prey during the 
