DISTOMA LANCEOLATUM. 275 



to lead nearly up to an organ which may represent the germ-stock 

 of the Trematoda. 



The female genitalia consist of a pair of very small dendritic 

 yelk-sacs, placed at the sides of the animal, in the middle of its 

 length, and united by a straight branch running transversely 

 across the animal. Immediately behind this point of junction 

 lies an organ with clear, white, globular structures, which may 

 be the germ-stock. It is probable that the spermatozoa coming 

 from the internal seminal vesicle, the vitelline bodies, and germ- 

 cells here meet together, for behind this spot Ave soon meet with 

 the true eggs in course of formation. These structures occur in 

 the convolutions of a very long oviduct, which is repeatedly 

 twisted into loops, and which passes directly into the uterus. 

 The further these convolutions pass backwards, the yellower they 

 become, until at last they are quite of a dark yellow colour when 

 they arrive in the neighbourhood of the caudal extremity of the 

 animal. From this point the loops turn back again, and continue 

 forming loops in the same way as before, often covering the loops 

 of the first scries, either entirely or partially. When this con- 

 voluted tube has returned about half its way forwards, the eggs 

 acquire a dark-brown colour, and these brown convolutions are 

 seen to pass up to the level of the anterior extremities of the two 

 yelk-sacs, aud at last end in a very long vagina, which is at first 

 convoluted, but afterwards runs straight, and opens, with the 

 penis, on the anterior margin of the ventral sucker. In the full 

 condition it is verv easv to detect this last circumstance. 



The system of excretory vessels consists of a pair of longi- 

 tudinal canals, which run quite at the sides of the animal, 

 reaching in front nearly to the pharynx, where they bend round, 

 and become thicker posteriorly to their extremities. At the 

 apex of the abdomen these two stems open into a common 

 dilated portion, and allow their contents to escape through a 

 cleft opening in the middle of the abdomen of the Distoma. 

 This canal is often seen produced externally in the form of a 

 bell, and only then opening. 



The pathological anatomy is much less characteristic than in 

 the case of D. hepaticum. There are properly no perceptible 

 great injuries to the liver. The diagnosis is only possible when 

 the worms pass of; the prognosis is better than with D. hepa- 

 ticum ; the etiology is unknown ; and the therapeutics are the 

 same as with D. hepaticum. 



