COCKROACH. 
338 
pericardial space, and drives it forwards by a slender aorta. 
The blood circulates, however, within ill-defined spaces in 
the body. 
Excretory system. 
There are sixty or so fine (Mal- 
pighian) tubules, which rise in six bundles from the begin- 
ning of the ileum, and twine through the “fatty body” 
and in the abdominal cavity. The absence of nephridia 
in insects has been already mentioned. 
REPRODUCTIVE SYSTEM 
OF THE MALE. 
OF THE FEMALE. 
The testes are paired organs, sur- 
rounded by the fatty body 
below the 5th and 6th ab- 
dominal terga. They atrophy 
in the adult. 
From the testes, two narrow ducts 
or vasa deferentia lead to two 
seminal vesicles. 
These seminal vesicles (the 
‘*mushroom - shaped gland”) 
open into the top of the ejacu- 
latory duct. 
This duct opens between the gth 
and ioth sterna. Beside the 
aperture, there are copulatory 
structures (gonapophyses). 
With the ejaculatory duct a 
gland is associated. 
Large branched tubular glands 
secrete a volatile alkaline sub- 
stance, with a strong mousy 
odour, probably offensive to 
enemies, 
The ovaries are paired organs, in 
the posterior abdominal region, 
each consisting of eight ovarian 
tubes. These are bead-like 
strings of ova at various stages 
of ripeness, 
From the ovarian tubes of each 
side eight eggs pass at a time |, 
into a short wide oviduct. 
The two oviducts unite and open 
in a median aperture on the 
8th abdominal sternum. Be- 
side the aperture are hard 
structures (gonapophyses) 
which help in the egg-laying. 
On the gth abdominal sternite a 
pair of arborescent glands pour 
out their cementing secretion 
by two apertures. The sper- 
matheca is a paired sac opening 
between the 8th and the gth 
abdominal sternum. 
Sixteen ova, one from each ovarian tube, are usually 
enclosed within each egg-capsule. 
The latter is formed 
from the partly calcareous secretion of the arborescent. 
