The Rot 379 



THE EOT— THE LIVER FLUKE. 



DefinitioiL — A disease of the sheep caused by the presence 

 in the liver of a flat worm, of the order Trematoda, and 

 known as the liver fluke, Fasciola hepatica. 



Cause. — The close attention which has been given of late 

 years to the study of parasites has resulted in a history 

 almost complete of the fluke worm. The mature worm 

 throws off several thousand eggs, which pass with the feces 

 from the anus. Some of them are carried by rains, or the 

 feet of passing animals, into water courses. There they de- 

 veloj) into higher forms, and take up their residence, for a 

 time, in the bodies of shell fish and water insects. At the 

 time of an inundation, numbers of them, with and without 

 their hosts, are left on the meadows. The sheep eat them 

 with the grass, and the miniature fluke passes down the 

 bowel until it reaches the liver duct, which it ascends, and 

 forthwith begins its final development and ovulation. 



Hence it is that the rot is especially prevalent during the 

 spring of the year, when rains are abundant and freshets 

 frequent ; in wet seasons, when the meadows are damp and 

 overflowed at times ; and on low grounds, where the transfer 

 of aquatic worms, etc., to the soil is rendered easy. 



The fluke itself is a flat, transparent or whitish worm, 

 from half an inch to an inch in length, and about a third as 

 much in breadth. It is usually found in the liver, but 

 occasionally in other internal organs. Their number is fre- 

 quently enormous, reaching occasionally to eight hundred or 

 a thousand individuals in a single liver. 



Symptoms. — In wet seasons, and in certain localities, the 

 loss by the rot in sheep is very heavy. It is quite destructive 

 in Australia, at times in England, and in some parts of the 

 United States. Hence it becomes of prime importance t(r 



