PASCIOLA HBPATICA. 



155 



main trunk divides into three branclieSj two of which approach 

 the ventral surface, shghtly diverge and pass forward towards the 

 head, whilst the tliird is continued on the dorsal surface in the 

 middle line, forming, as it were, a continuation of the main trunk. 

 This branch, however, is the most feebly developed of the three. 

 During its course upwards towards the head, the main trunk gives 

 off a variable number of main primary branches, all of which are 

 directed diagonally upwards and forwards ; and besides these, there 

 are many smaller primary branches intercalated, as it were, between 



Fia. 34. — Mode of termination of the coeca of the so-called excretory or water-vascular system of 

 canals in Fasciola hepatioa (X 40 diam.). Outlined with the aid of a camera. — Original. 



the larger primary vessels. At a short distance from the central 

 line, these vascular branches freely anastomose by the intervention 

 of secondary and tertiary branches, and also by intermediary twigs, 

 which cannot be said to be referable to one main branch more than 

 another. Some of the non-anastomosing ultimate twigs, which 

 are very numerous, are directed towards the dorsal surface, where 

 they terminate in coecal extremities immediately below the muscular 

 layers, whilst others are continued towards the lateral margins, 

 where they also terminate in a similar manner. Under the half- 



