200 
Psyche 
[December 
GESTATION (DAYS) 
Fig. 1. Oocyte development during pregnancy in N. cinerea. All points 
from 0-34 days are mean values of 5 - 9 individuals (N — 197) ; standard 
errors are not indicated but were ± 0.04 mm. or less for all of these 
measurements. Each point beyond 35 days of pregnancy represents the 
oocytes of one female. Open circles = females were still carrying oothecae 
when dissected. Solid circles — females dissected at the time of parturition 
or within 24 hr. after giving birth. The horizontal line is drawn at 1 mm. 
which is about the minimum size of the oocytes that contain yolk. 
on the corpora allata has been removed. The older the uterine 
eggs when removed, the less time is required to ovulate again 
(fig. 2). Roth and Stay (1959, 1961, 1962a, b) concluded that 
mechanical stimuli resulting from the ootheca in the uterus inhib’t 
the corpora allata during pregnancy. Engelmann (1964) believes 
that in L. maderae the corpora allata are inhibited by a substance 
