The Rot in Sheep. 



41 



two distomata, supposing- such to be necessary for fructifying 

 their ova. We, however, incline to the belief that no such con- 

 tact does take place, but that the entozoon is self-impregnating. 



Digestive System. — This part of the organism of the distoma 

 is more simple in its arrangement than many other portions, and 

 although it has been described with much minuteness, several of 

 these accounts are very far from correct. It commences at the 

 bottom of the mouth or oral sucker as a single tube or oesophagus, 

 which runs for a short distance directly downwards, and then 

 divides into two main intestinal branches (see figs. 5 and 6). 

 These branches diverge from each other, and in so doing they 

 approach the outer borders of the entozoon. This divergence 

 is greatest opposite to the ventral sucker, below which the tubes 

 again converge a little, and then run in a parallel course towards 

 the caudal extremity, where they split up into numerous fine 

 divisions. Where their divergence is most, there also the tubes 

 are largest, being often pouch-like in their form. Prior to 

 their dilatation, they give off from their outer side four or five 

 smaller branches, which take an upward direction in this the 

 cervical portion of the entozoon and run towards the margin of 

 the neck, dividing in their course in an arborescent manner into 

 numerous fine canals, to end ultimately in minute cceca (fig> 5). 



Immediately below these, usually about fifteen other branches 

 leave each parent trunk, also on its outer side, and take a similar 

 course, dividing and ending in the same way. These branches, 

 however, all incline more or less downwards. The parent trunks, 

 thus diminished in size, next split up in the way before described. 

 A few branches — rarely more than five or six — leave the trunks 

 on their inner side, and running a very short distance towards the 

 medium line of the distoma, end likewise in a similar manner. 

 The situation of the intestinal tubes is about central between the 

 dorsal and ventral surfaces of the entozoon, so that they are 

 visible on either side. The general arrangement of the trunks 

 and branches is very well depicted in the engraving on the 

 opposite page, fig. 5. 



In this illustration, and also in the one following (Jig. 1>), 

 (i marks the oral sucker, b the oesophagus, and c its division into 

 the two intestinal branches or parent trunks from which the 

 others spring. 



In fig. (5, an attempt has been made to depict the arrangement 

 of the muscular fibres at the origin of the digestive organs, but 

 not with the success which we could have wished. 



Oral Sucker (Hi (I (Esophagus. — These parts of the distoma seem 

 not to have received that amount of attention which is necessary 

 to explain the double function thev have to perform — namely, 

 of an inlet and outlet to the bile on which the entozoon exists 



