1962] 
Roth and Stay — Cockroaches 
203 
manually, part of the egg cases were cut off and the remainder pushed 
back into the uterus in an attempt to free the pressure normally exert- 
ed on the ovipositor. In 6 successful operations the ovipositors were 
freed 9 to 12 days after ovulation, and at 73 to 75 days of “pregnancy” 
their oocytes were 1.47 ±0.03 mm. Seven females in which the opera- 
tions (7 to 18 days after ovulation) did not free the ovipositors, had 
oocytes 1.49=1=0.05 mm. after carrying their oothecae for 71 to 76 
days; one female that was unsuccessfully operated upon 8 days after 
ovulation had oocytes 3.77 mm. 64 days later. These experiments 
indicate that removing the ovipositor or releasing the pressure of the 
ootheca on the ovipositor during the gestation period does not influence 
the development of the oocytes. The two individuals in which the 
oocytes grew may be explained by the fact that inhibition of the cor- 
pora allata in some virgins of Byrsotria may break down during gesta- 
tion. 
Blaberus craniifer: Parts of oothecae (about 5 mm. x 10 mm.) of 
B. craniifer were implanted into the abdomens of 9 virgin females less 
than 1 to 3 days old (one female had an entire ootheca implanted). 
Eight females dissected 15 to 30 days later had well developed oocytes 
4.84=1=0.28 mm.; one female dissected 28 days after the implant 
showed no growth of oocytes (1.48 mm. long). The oocytes of 
unoperated virgins 15 to 30 days old were 5.10=1=0.05 mm. The 
length of mature oocytes are about 6.25=1=0.07 mm. (N— 3) ; the new 
basal oocyte at ovulation is 1.10=1=0.03 mm. (N = 5). Uterine eggs 
implanted into the abdomens of virgin females did not inhibit oocyte 
development in B. craniifer. 
Six mated females had their nerve cords severed on the twenty- 
second to twenty-sixth days of pregnancy and were dissected 34 to 39 
days later. Four of these females (operated on the twenty- fifth 
to twenty-sixth day of pregnancy) had oocytes 4.09=1=0.84 mm., 34 to 
38 days later (fig. 12 B) ; two females operated on the twenty-second 
and twenty-third days of pregnancy showed very little oocyte develop- 
ment (1.74=1=0.12 mm.), 34 and 39 days later (the oocytes at par- 
turition are 1.56=1=0.07 mm. long; N = 6 ). 
Two virgin females of B. craniifer carried their oothecae for 93 
and 107 days, which is longer than the normal gestation period (about 
79 days) of mated females. When the undeveloped uterine eggs were 
extruded the oocytes measured 3.92 mm. and 3.68 mm. respectively 
(fig. 12C). Inhibition of the corpora allata in B. craniifer apparently 
can break down in the late stage of “pregnancy” in virgin females, 
as it does in Byrsotria and in Pycnoscelus. 
Blaberus giganteus: Eight pregnant females were taken from cul- 
