I30 



either salt or lime may be scattered over its surface with advantage. Both these 

 substances destroy the embryos of the fluke, and, at a later period, the cysts, when 

 attached to the grass. And, still further, they will destroy the snails, which serve 

 as hosts to the intermediate stages of the liver fluke. The freedom from rot of sheep 

 which are feeding on salt marshes is well known, and is now shown to be due to the 

 poisonous action of the salt on the embryos, sporocyst, redia, cercaria, and cyst, and to 

 its similar action on ^ Limnceus truncatulus' itself. Even a weak solution of salt and 

 water (f per cent of salt) proves fatal to this snail. Dressings of salt have the 

 advantage over lime in not spoiling the grass for immediate use, whereas the latter 

 will do so. It may, however, be better at times for the land itself that lime should 

 be applied. 



There seems to be only this one snail in England which can serve as a host to 

 the intermediate forms of the liver fluke. Consequently, wherever this snail is 

 absent, there can be no liver rot ; and if we could succeed in exterminating it, we 

 should render it impossible for the disease to exist in England. 



It is naturally of much importance that salt or lime should be distributed at the 

 right time of the year, when fluke germs and snails are present in the greatest num- 

 bers. The snail buries itself in mud or soil in the winter time, and, owing to the 

 cold, no embryos are hatched at that period. 



If the weather be warm in April, it is possible that a few may be brought out 

 towards the end of the month, but they will not be numerous. In May, however, 

 greater numbers may be hatched, and still more in June and July. These two 

 months are the time of the year when the country is most liable to be infested by 

 snails. As more eggs are distributed through the whole of the summer by fluked 

 animals, it is clear, of course, that the production of embryos, though in less numbers, 

 will continue from August until the time when the development is checked by autum- 

 nal cold. June and July, then, are the principal, but not the only, months in which 

 we are to wage war against the embryos ; the latter part of August, September, and 

 October, are the months in which, especially, to destroy the germs on the grass 

 ready for transference to the sheep." 



313. In the autumn, the snail, Limncsus Trnncaiiilus, just before going 

 into its winter quarters, i.e., burying itself in the mud, may become 

 infested with one for more embryos, and, or the want of heat, their 

 further developement is arrested until spring, when the rays of the 

 sun bring the snail to the surface of the ground, and the various 

 transformation stages of the embryo-fluke is then carried on, always 

 provided heat and moisture are present. This, to my mmd, is the 

 greatest cause of the infection. The eggs deposited by the mature 

 flukes in the liver, and again deposited on the ground in the winter 

 months, are in great danger of being destroyed by the want of heat to 

 germinate the embryo, as well as by the absence of its intermediate host, 

 the snail, which is in its winter habitat. Sometimes, however, too 



