Psyche 
[December 
1 66 
to 25 0 C. and 50 to 70% relative humidity. Engelmann ( 1957, 1959) 
showed that yolk deposition and growth of the oocytes are correlated 
with and dependent upon activity of the corpora allata in Leucophaea 
and Diploptera and we have used oocyte development as an indicator 
of endocrine activity. Measurements were made, with an ocular mic- 
rometer, of oocytes that were dissected from ovaries in Ringer’s solu- 
tion. Our measurements of the oocytes of Leucophaea are larger than 
those reported by Engelmann (i960). This discrepancy is probably 
due to the fact that he measured the oocytes after fixation (Engel- 
mann, 1957). We measured one large oocyte per female; in establish- 
ing the normal ovarian cycle or the sizes of the oocytes at a specific 
period a number of females were usually dissected to give some indica- 
tion of the extent of variation. Various operations ( allatectomy, nerve 
cord severance, etc.) were performed on insects kept under carbon 
dioxide anesthesia. 
The species reported on in this paper are Pycnoscelus surinamensis 
(Linnaeus), Byrsotria fumigata (Guerin), Blaberus craniifer Bur- 
meister, Blaberus giganteus (Linnaeus), Nauphoeta cinerea (Olivier), 
and Leucophaea maderae. There are two strains of Pycnoscelus suri- 
namensis which differ physiologically. The bisexual strain cannot 
reproduce parthenogenetically and the parthenogenetic strain females 
when mated to males of the bisexual form show a reduction in fertility 
and the resulting offspring are all females which reproduce partheno- 
genetically (Roth and Willis, 1961). Practically all of the experi- 
ments on Pycnoscelus were done on the parthenogenetic strain but a 
few were performed on the bisexual form. A similar study on control 
of oocyte development in Diploptera and two species of Blattella has 
been reported elsewhere (Roth and Stay, 1961, 1962). 
RESULTS AND DISCUSSION 
Oocyte development in virgin and mated females 
Pycnoscelus surinamensis : Biological data for the two strains are 
given in table 1. The basal oocytes of the ovarioles of females less 
than a day old are large and may already contain yolk. In fact yolk 
may be present in the oocytes of some newly-emerged adults indicating 
that perhaps gonadotropic hormone had already been released in the 
nymphal stage. The ovarian cycle from emergence to the formation 
of the second ootheca in the parthenogenetic strain is shown in figure 
1. During gestation the oocytes remain small and increase only slight- 
ly in length during the development of the eggs in the uterus. Yolk 
deposition occurs after parturition and the oocytes increase rapidly in 
size. 
