1964] 
Roth — Reproduction in Cockroaches 
217 
Fig. 11. Relationship between age of ootheca when removed from the 
uterus and recovery of receptivity in N. cinerea. Numbers in circles = 
numbers of insects used. Numbers in parentheses — number of days females 
were pregnant when their oothecae were removed from the uteri. Numbers 
under parentheses = mean length (mm.) ± standard errors of the oocytes, 
measured at the time of mating (except for females represented by open 
squares; the oocytes of these females were measured <24 hr. after mating). 
(AP) = females that gave birth normally; fifty-five per cent of the females 
mated <24 hr. after parturition and these are plotted at 0.5 day. The 
females of this group that failed to mate oviposited 6-10 days after partu- 
rition. Open circles = virgin females; all other groups had mated prior 
to ovipositing. Open squares — each of the females in this group were 
confined with 2 males continuously until they mated; females examined daily 
for spermatophores. The females in all other groups were tested for 
receptivity once a day for one hr. (2 $ $ : 1$) and were removed when 
they mated. The per cent mating is expressed as accumulative data. (Room 
temperature.) 
1) prolonged loss of receptivity during gestation can be induced by 
mating stimuli, i.e. t the firm insertion of the spermatophore in the 
bursa copulatrix, and 2) the absence of sperm in the spermathecae 
does not influence the return of receptivity after the first oviposition. 
Males produce small spermatophores if they mate more than once 
with brief intervals between matings (Roth, 1964) and it is probable 
