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" The adult fluke, in the liver of the sheep produces enormous numbers of eggs, 

 which are distributed with the droppings of the sheep. If these eggs have moisture, 

 and a suitable degree of warmth, they continue to live, and in each is formed an 

 embryo. The embryo leaves the egg, and swims in search of the particular snail, 

 ' Limnans triincatuhis,' within which its future life and growth take place. The 

 embryo bores into the snail, and then grows into the form which is called a sporocysi. 

 The sporocyst gives rise to the second generation. This is known as redicr. The 

 redicF, in turn, produces the third generation, which has the form of a tadpole, and is 

 called cercaria. The ceiraria quit the snail, and enclose themselves in envelopes, or 

 cysts, which are attached to the grass. When the grass to which the cysts adhere 

 is eaten by the sheep, or other suitable host, the young liver fluke comes out of the 

 cyst and takes up its abode in the liver of its host, and the fatal circle is thus 

 completed. It will be seen, therefore, that the fluke disease is one which alternates 

 between a particular snail and the sheep. A sheep cannot take the infection directly 

 from another sheep, nor can one snail take it directly from another snail. The sheep, 

 by spreading the eggs of the fluke, gives infection to the snail, and the snail, in turn, 

 by harbouring and distributing the cercaricF, conveys the infection to the sheep. 



The conditions necessary for the e.xistence of liver-rot, in any given locality, are 

 as follows ; — 



I. — There must be fluke eggs on the ground. 



2. — There must be wet ground, or water, during the warmer weather, for the 

 eggs to hatch in. 



3. — A particular snail, called ' Limnceus triincatulus,' must be present. 



4. — Sheep, or other animals, must be allowed to feed on the same ground, 

 without proper precautions being taken. 



If any one of these conditions remains unsatisfied, there can be no fluke-disease 

 or liver-rot in the locality. 



If the eggs of the liver-fluke are to be hatched, they must be in water, or, at 

 least, be kept moist, during some weeks of warm weather, or even some months, if 

 the temperature be lower. If the eggs are once thoroughly dried, their vitality is 

 destroyed, the side of the shell being usually crushed in. A temperature of about 

 74° to 78" Fahr. is the most favourable, and then the embryo is formed in about 

 two or three weeks ; with less warmth, progress is slower, and with an average 

 temperature of 60'' the growth occupies two or three months. 



Ground is often, with reference to the 'rot,' spoken of as 'sound,' or, on the 

 contrary, as ' rotting.' When the droppmgs, containing fluke eggs, fall on to a field, 

 the rain will distribute the eggs over the surface, washing them down to the roots of 

 the grass. If the soil be light or sandy, and porous, the land will be ' sound,' for the 

 water will filter into the earth, leaving the eggs on the surface, where they will get 

 dried, and so be destroyed. If, on the other hand, the soil is heavy and clayey, so 

 that the rain-water does not sink into the ground, but flows along the surface, the 

 ground is ' rotting.' For, as the water flows over the surface, it carries the fluke-eggs 

 along with it, and deposits them in ditches, holes, marshy places, or furrows, where 

 the water stands— all of them provinces where the eggs will hatch. The obvious 

 remedy for this evil is to drain the land thoroughly and efficiently, and it will not 

 only do much to prevent the rot, but will have the further advantage of greatly 

 improving the herbage. Where it is not practicable to adopt this remedy at once, 



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