330 ARTHUR WILLEY. 
These central cavities in the immature testes may therefore 
be called the genital ceca, and the genital products appear 
to arise as proliferations of the walls of the ceca (figs. 5 
and 6). 
What is very puzzling is the fact that similar proliferations 
occur on the walls of the terminal gastric lobes themselves 
(fig. 5). On the dorsal walls of the terminal gastric lobes the 
cells of these proliferations appear to assume the properties of 
chloragogenous cells, and numerous yellowish refringent con- 
cretions occur in and amongst them. Somewhat similar re- 
fringent particles are to be seen in the cells of the subjacent 
true endoderm. Finally, in connection with this subject I can 
only mention the fact that as the median walls of the neigh- 
bouring terminal lobes fuse together on nearing the median 
canal which connects them with the stomach, the minute 
cellules which compose the greater part of the proliferations 
in question are replaced by long pyramidal cells which com- 
pose a compact gland, having a radiating structure due to the 
peculiar arrangement of the cells. I will call thisa gastric 
gland, and hope that at some future date light may be 
thrown upon its nature. 
What distinguishes the genital proliferations from the 
above-described gastric proliferations, apart from their 
different topographical relations, is the fact that the nuclei of 
the cellules of the former are of different sizes (fig. 9). The 
larger nuclei I interpret as belonging to spermatogonia and 
the smaller to spermatocytes. Unfortunately 1 am unable 
to make out any nuclear structure in my preparations, although 
they are otherwise well enough preserved. 
The spermatozoa form dense clusters with characteristically 
deeply stained heads and unstained tails. The tails are directed 
both outwardly and mesially. When a testis contains only 
mature spermatozoa there is no longer any trace of the genital 
cecum (fig. 7). 
With regard to the ducts in one individual, I counted no 
less than twelve ducts, which were distributed equally between 
the four testes. Of these ducts 1 was able to see the actual 
