1964] 
Roth — Reproduction in Cockroaches 
201 
, AP , 
-(36-49) 
4.6 ± 0.2 
@ 
( 10 - 11 ) 
23.4±0.6 
— (< 1 ) 
33.4i 1.0 
/ 
0 5 10 15 20 25 30 35 40 
DAYS AFTER REMOVING OOTHECA FROM UTERUS 
Fig. 2. Relationship between the age of the ootheca at the time it was 
removed from the uterus of N. cinerea and the time required to form a 
new egg case. Numbers in circles — number of insects used for each curve. 
Numbers in parentheses = number of days females were pregnant when 
their oothecae were removed. AP = after parturition; 36-49 represents 
the range (days) of gestation in these females. Numbers under paren- 
theses — mean number of days ± standard error, to form a new ootheca. 
The per cent ovipositing is expressed as accumulative data. 
released by the egg case or brood sac, acting on neurones in the nerve 
cord and brain. 
To determine if a chemical agent or mechanical stimulation 
prevents the growth of oocytes in N. cinerea during pregnancy, glass 
tubes were inserted in the uteri of females after their oothecae were 
removed at 3 different periods of gestation. The results (figs. 3,4) 
show that with glass oothecae, the oocytes did not develop as rapidly 
as they did in females in which no tubes were inserted in the uteri, 
indicating that the corpora allata were inhibited by the artificial egg 
cases. When oothecae were removed about 24 hours after oviposition, 
females oviposited again cn an average of 33 days; when oothecae 
were removed 10 - 1 1 days after oviposition, the average time taken 
to oviposit again was 23 days (fig. 2). In both groups of females 
