100 
Tlie Rot in Sheep. 
colourless fluid, among which are numerous granules. These 
tubes would seem to be chiefly concerned in nutrition, but 
whether they have or not any direct communication with the 
true digestive system we have been unable to determine. Indeed, 
this is a point in connection with the organism of the distoma on 
which we hesitate to speak with confidence. In the young flukes, 
referred to at parje 94, the aquiferous system appeared to be so 
connected. 
In distomata which contain but little bile the aquiferous tubes 
are seen to advantage, but we have failed to find them united to a 
single vessel centrally placed, as described by some authorities. 
We have also been unable to detect the so-called " excreting 
organ " of Van Beneden, Aubcrt, and others, which is said to be 
situated near the caudal extremity of the entozoon, and to receive 
the contents of this single vessel. Is it possible that the " ex- 
creting organ " has been confounded with an occasional dilata- 
tion of one of thjB tubes connected with the external male organ 
— the vasa deferentia — at its inferior extremity ? We have often 
found one, and sometimes both of these tubes to' be thus dilated ; 
although in the majority of instances such is not the case. 
The readiness with which distomata imbibe tepid water, 
which causes them to swell out and become very opaque, led 
us in our original investigations to suppose that these aquiferous 
tubes might receive their contents by endosmosis, and we had 
recourse to a variety of experiments with coloured fluids to deter- 
mine the point. At length we concluded, however, that such 
was not the case, although we found that distomata placed in 
tepid bile would imbibe some of this fluid, yet by no means so 
quickly nor in such quantity as they did water. 
Ventral Sucker. — Before describing the internal structures of 
the fluke, we will add a few words in this place on the ventral 
sucker, a magnified view of which, when detached from the body, 
is here inserted. See Jig. 4. 
Fig. 4. 
Magnified view of the Ventral Sucker. 
This organ consists of an outermost raised border, of a circular 
form, surrounding a concave or sunken centre, which is imper- 
