1964] 
Roth — Reproduction in Cockroaches 
241 
fumigata (Guerin) and the bisexual strain of Pycnoscelus surina- 
mensis with unfertilized eggs in the uterus, the ootheca does not 
increase markedly in size because the eggs do not develop, inhibition 
of the corpora allata ceases prematurely, and consequently the 
oocytes develop in spite of the presence of the egg case (Roth and 
Stay, 1962b). The earlier return of corpora allata activity in some 
females of N. cinerea with glass tubes in the uteri (figs. 3, 4) may 
be due to the fact that there is no change in size of the 
uterus. A glass ootheca might be likened to the presence of unferti- 
lized eggs in the brood sac. In both strains of P. surinamensis the 
glass rods were more effective inhibitors than the beads. Perhaps the 
shape of the insert, in this species, influences the degree of inhibition ; 
the shape of a glass rod is more like an ootheca than is a bead. 
During normal pregnancy, the length of time the corpora allata 
are inhibited differs between P. surinamensis and N. cinerea. Inhibi- 
tion frequently ceases shortly before parturition in N. cinerea and 
only after parturition in P. surinamensis. The species difference 
might account for the greater effectiveness of glass rods in inhibiting 
the corpora allata in P. surinamensis. 
SUMMARY 
During gestation in N. cinerea the mechanical presence of the 
ootheca inhibits sexual receptivity. The prerequisites for the return 
of receptivity in the normal period of time, after oviposition or 
parturition, are: 1) the presence of an ootheca (i.e., uterine stretch- 
ing for at least a short period, and then 2) the removal of the 
ootheca (i.e., the stretch stimuli). 
Return of receptivity can usually be correlated with the beginning 
of yolk deposition in the oocytes. But the corpora allata do not 
control receptivity since allatectomized females mate. As shown for 
the first preoviposition period, return of receptivity after parturition 
is correlated with some event that occurs at about the same time as 
onset of corpus allatum activity. Some center, perhaps affected by the 
neurosecretory system in the brain, controls receptivity by controlling 
the response of the female to the male’s pheromone. 
Females of N. cinerea which mate after giving birth have small 
oocytes; females which do not mate have large oocytes. After partu- 
rition, in N. cinerea and L. maderae , the oocytes mature rapidly, and 
the females become unreceptive, if they are isolated from males for 
several days. The data suggest that a high hormone (neurosecre- 
tion?) titer, after parturition, may inhibit receptivity. 
