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Psyche 
[December 
2 strains of P. surinamensis. The artificial oothecae were inserted 
into the uteri of females after their oothecae were removed <24 hr. 
after ovipositing. The results are shown in figure 5 and table 1. The 
oocytes of some females with bead inserts developed as rapidly as in 
females without beads. In the bisexual strain, the largest bead, and 
consequently the greatest uterine streching, was more effective than 
the two smaller beads in inhibiting the corpora allata. In the parthe- 
nogenetic strain, 4.0 mm. beads were about as effective as 4.5 mm. 
beads ( table 1 ) . The bead experiments were conducted for a maxi- 
mum of 56 days in the parthenogenetic strain and for 37 days in the 
bisexual strain. In the glass rod experiments, females were sacrificed 
from 27 - 100 days after the rods were inserted in the uteri. Inhi- 
bition was virtually complete in all females (table 1), their oocytes 
ranging in size from 0.58 -0.88 mm. long (x = 0.74 d= 0.01 mm.). 
Of 68 bisexual strain females that had rods inserted in their uteri, 
only 3 females had well-developed oocytes when examined on the 
17th, 25th, and 36th days. The other 65 females had oocytes that 
were virtually completely undeveloped when examined 24-71 days 
after the rods were inserted ; their oocytes ranged from 0.54 - 0.95 
mm. and averaged 0.71 ± 0.01 mm. in length. 
It was of interest to determine if reduction in size of the ootheca 
would influence the size of the ovarian oocytes at parturition. There 
are an average of 33 eggs in the ootheca of N. cinerea (Willis et al., 
1958). The results of reducing the number of eggs in the ootheca 
are shown in figure 6. The oocytes of females that had carried small 
oothecae were not larger than the oocytes of the control females. 
Fig. 5. Effect of distention of the uterus with glass beads on inhibition 
of the corpora allata during gestation in two strains of P. surinamensis. 
Solid circles — Carrying oothecae (controls). Each point represents one 
female or is an average value of 2-5 females. Bisexual — N = 107; 
parthenogenetic — N = 75. Open circles — Oothecae removed <24 hr. after 
ovipositing; no glass beads inserted in uteri. Bisexual — 9-16 females per 
point (N = 189); parthenogenetic — 4-14 females per point (N = 96). 
The 3 remaining symbols were females whose oothecae were removed <24 
hr. after oviposition and glass beads of the following approximate diameters 
were inserted in the uteri; open squares = 3.5 mm. Bisexual — 7- 11 females 
per point (N = 86); parthenogenetic — 5-8 females per point (N = 36). 
Open triangles — 4.0 mm. Bisexual — 8-15 females per point (N — 65); 
parthenogenetic — 3-10 females per point (N = 48); solid squares = 4.5 
mm. Bisexual — 10-13 females per point (N = 44); parthenogenetic — 
6-9 females per point (N = 49). Curves are drawn through solid and 
open circles only. For the points indicating females with bead inserts, 
vertical lines are one standard error of mean values; no vertical lines 
indicate standard errors of ± 0.02 mm. or less. 
