58 
Psyche 
[June 
Evidence for Intra-uterine Nutrition 
The weight, water, and dry matter changes which ac- 
companied the increase in egg size are shown in figure 1; 
a series of oothecae containing eggs of different sizes are 
shown in figures 5-9. The smallest eggs (0.93 mm.) un- 
doubtedly were from a very recently formed ootheca. Hagan 
(1951) stated that the freshly deposited egg is approxi- 
mately 1.20 mm. long. The largest eggs (6.9 mm.) repre- 
sent fully matured embryos, inasmuch as some of the eggs 
in this ootheca began to hatch shortly after they were 
manually extruded from the female (figs. 9-13). The dif- 
ference in size between the smallest and largest eggs 
represents more than a seven-fold increase during em- 
bryogenesis. The size and weight of the eggs increase with 
acquisition of both water and solids. However, most of 
the weight increase arises from absorption of water. From 
the smallest to the largest eggs there was an increase of 
about 50 times in the amount of dry matter and about 
85 times in water content. Visible differentiation was ac- 
companied by the first observed increase in dry matter 
(fig. 1, arrow). Prior to differentiation the eggs absorbed 
water only, and the dry matter content dropped from 
about 34% to about 26%. After differentiation became 
visible, the dry matter content remained at approximately 
26% throughout development. The increase in the size of 
the egg, as Hagan (1951) pointed out, cannot arise from 
the small amount of yolk available, nor could the increase 
in dry weight be interpreted on this basis. Obviously, ad- 
ditional nutriment is supplied by the mother to the eggs 
in the brood sac. The exact source of this nutriment is 
not known; Hagan (1941) suggested that nutriment may 
be secreted by the maternal accessory (colleterial) glands. 
Diploptera is unique among cockroaches in gaining solid 
matter from the mother during embryonic development. 
In oviparous cockroaches ( Blatta orientalis L., Blattella 
vaga Heb., Blattella germanica (L.) ) and false ovovivi- 
parous species ( Nauphoeta cinerea, Pycnoscelus surina- 
mensis (L.), and Leucophaea maderae (F.) ) solid matter 
is lost during embryogenesis, although water is absorbed 
from the ootheca or directly from the mother (Roth and 
