538 GEOFFREY SMITH. 
structure stretching from about the second thoracic seement 
to the extreme hind end of the abdomen (text-fig. 37). If we 
take a horizontal section through the ovary (PI. 12, fig. 14) 
we see that the lobes contain small immature ova while the 
external part of the tube is filled with large, nearly mature 
ova filled with a purplish yolk. The external wall of the 
lobed portion consists of small undifferentiated cells of the 
germinal epithelium. ‘The inner wall of the ovary consists 
of cells, most of which contain large nuclei which stain of an 
uniform dark colour with hematoxylin, while there is present 
a number of granules which stain deep black. These cells 
may be called the trophic cells. On their inner borders they 
are vacuolated, and it is evidently their function to elaborate 
food material, which they supply in the form of yolk to the 
developing ova. <A certain number of these trophic cells can 
be seen lying among the’ eggs in the middle of the tube. 
The oviducts are simple straight tubes lined with short 
columnar cells; they pass below the ventral muscles to open 
on the coxopodites of the sixth thoracic limbs. ‘hey are not 
supplied with any accessory glands. 
Male.—The testes (text-fig. 41) are coiled tubes running 
from the anterior thoracic region to the extreme hind end of 
the body. At the anterior end of the coiled tube a duct 
passes posteriorly, and then turning anteriorly again opens 
at the bases of the eighth thoracic limbs. 
In the glandular part of the testis of a young Anaspides 
we can study the process of spermatogenesis (Pl. 12, fig. 15). 
We see the primary and secondary spermatocytes under- 
going mitosis, and fully-formed spermatozoa. On the out- 
side of the tube we see large cells with darkly staining 
nuclei of an exactly similar appearance to the trophic cells 
found in the ovaries. These cells are not, however, to be 
observed in an adult testis. In an adult testis we only see 
nests of spermatocytes in various stages of spermatogenesis, 
or else groups of fully formed spermatozoa. 
The upper part of the descending duct is sterile, so far as 
the production of spermatozoa is concerned, and it is formed 
