DISEASES OF THE OX AND SHEEP. 455 



the round worms, or nematodes, e.g. the bilharzia, which occurs 

 chiefly in Egypt, where it causes a highly dangerous disease. 



Of the trematode worms, which are found infesting rumi- 

 nants, the most important is the Fasciola hepatica the well- 

 known liver-fluke of those animals. Allied to it is the Fasciola 

 Jacksonii of the elephant, and also the fluke found in the giraffe, 

 These three kinds of flukes are said to be the only ones in 

 which the intestinal canal is branched. 



THE FLUKE DISEASE IN SHEEP. 



Of all the disorders which now and again make their appear- 

 ance among large numbers of sheep, perhaps the best known and 

 most serious is that which is generally called sheep-rot, that 

 justly dreaded scourge, which arises from the presence of flukes 

 in the liver. 



After long-continued wet weather, and more especially follow- 

 ing upon a succession of wet seasons, the disease is particularly 

 violent. We cannot here write exhaustively on this subject, 

 since it is far more important as affecting sheep than any other 

 class of animals ; but, in view of the great value of knowledge 

 regarding it, we propose to mention a few points. The mixing 

 of salt with the food of sheep and cattle which are liable to the 

 attacks of flukes has been strongly recommended as a preventive 

 and curative agent ; but the scattering of salt or lime upon the 

 herbage is perhaps a still more potent preventive. 



It is not long since Professor A. P. Thomas elucidated the 

 subject by clearing up some doubtful points, and discovered that 

 the intermediary stages of the fluke are passed in the snail known 

 as the LimncBus truncatulus. It is possible that other snails may 

 also serve the same purpose ; but for the most part this particular 

 snail is the creature in which the ova which are scattered about 

 the land in the droppings of sheep or other animals infested with 

 the flukes, such, for example, as hares and rabbits, must develop, 

 before they can invade any other animal. In this connection it 

 is of no small moment that we should bear in mind that man 

 himself may be afflicted with liver-fluke, and that in such cases 

 the cysts containing the young flukes may probably be taken in 

 together with watercress, or in other ways. Hence watercress 

 should always be steeped in salt and water, and thoroughly 

 cleansed, before it is eaten. 



