The Hot in Sheep. 



39 



which we hesitate to speak with confidence. In the young flukes, 

 referred to at page 33, 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, Aubert, 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 the 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 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 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- 

 forate. The border is very firm compared with the general 

 surface of the body of the distoma, and is chiefly composed of 

 two sets of muscular fibres arranged after the manner of an ordi- 

 nary sphincter. Muscular fibres also radiate from the centre of 

 the sunken part towards the outer edge of the border. 'Flic whole 

 arrangement is beautifully adapted lor the attachment of the 



