254 
FRANK E. BEDDARD. 
as they are completely overgrown and surrounded . by the 
vesiculse seminales of their respective segments. 
The fact that the testes are actually surrounded by the 
vesiculse during the growth of the latter is, of course, a result 
of numerous investigations. The adult structure of the 
Earthworm at present under consideration would prove this 
point, supposing, that is to say, that there was the least need 
of proof. 
The sac-like vesiculse seminales completely enclose the testes, 
and in the case of the anterior pair, at any rate, enclose also a 
tuft of nephridial tubules, which happen to be closely associated 
with the testes. In other worms other organs of the body, 
e. g. the ventral blood-vessel, are enclosed within the cavity of 
the vesiculse. 
The testes of Dichogaster have apparently the same 
structure that characterises these organs in other Earthworms. 
They are attached to the mesentery close to the ventral median 
line on either side of the nerve-cord ; at the point where they 
are attached the walls of the vesiculse come into contact, and 
are fused with the mesentery. 
The structure of the vesiculse seminales is curious and differs 
in certain particulars from the vesiculse of other Earthworms. 
In the example which I dissected the eleventh and twelfth 
segments contained each a pair of racemose structures of small 
size (fig. 15, r.'), appearing on each side of the gut. These 
presented every resemblance to the vesiculse seminales of many 
species of Acanthodrilus. In the tenth segment a mass of 
developing spermatozoa occupied the ventral region of the seg- 
ment, and partly obscured the fimbriated apertures of the vasa 
deferentia. A study of the generative apparatus by means of 
transverse sections showed that the structure in segment 10 is 
not a loose mass of developing spermatozoa set free from the 
vesiculse of segments 11 and 12, and ready to be extruded 
through the open funnels of the vasa deferentia. It is really 
a pair of vesiculse seminales (fig. 15, r .) with a delicate outer 
wall, and presenting the usual structure. This vesicle, al- 
though presumably originally a paired structure, does not show 
