458 THE DISEASES AND DISORDERS OE THE OX. 



number of deaths from sheep-rot was about one and a half 

 million, worth perhaps as much as 564,000,000 sterling. Indeed, 

 the average annual loss from sheep-rot has been said to be about 

 one million. The number of sheep which were lost in the season 

 1879 to 1880 and in the succeeding season has been estimated in 

 each case at about three millions. After long-continued wet 

 weather, and more especially after a succession of wet seasons 

 the disease is most markedly prevalent. 



The liver-fluke is flat, of a pale brownish-yellow colour with 

 a slight rose or pinkish tint ; and when adult it is upwards of 

 about one inch or even one and a half inch in length, and about 

 half-an-inch from side to side in its widest part. When, how- 

 ever, the young creature first gains access to the liver, it is 

 only about one-eightieth of an inch in length. 



In sheep afflicted with the disease, the eggs occur in large 

 numbers in the bile-ducts and gall-bladder, imparting a dark 

 colour and a sandy appearance to the bile. It has been esti- 

 mated that each adult fluke may produce as many as half a 

 million eggs. Mixed with the bile they pass together with that 

 fluid into the intestines, wherefrom they are at length expelled 

 and distributed upon the ground together with the droppings. 

 Provided that they meet with a suitable degree of warmth and 

 moisture, these eggs will live, and inside each of those which meet 

 with favourable conditions an embryo becomes developed, strug- 

 gles out of the egg-covering, and swims about in any water 

 which may be at hand, until it may perchance come into contact 

 with the particular snail known scientifically as the LimncBUs 

 truncatulusy within which creature its further development must 

 be proceeded with, if it is to go on at all. However, it is quite 

 possible that certain other snails are, as we said above, also 

 capable of acting this same part of intermediary bearer. The 

 embryo is provided with a structure known as a head-papilla, 

 which can be drawn in during the act of swimming, and can also 

 be utilised as an effective boring-tool when the little creature 

 happens to come in contact with its host. The embryo lives 

 about eight hours in water, and then bores its way, possibly 

 through the muscular foot, into the little snail known as the 

 Limnceus truncatulus. 



The embryo bores its way into the snail, and, having entered 

 into it, undergoes certain changes, becoming, in the first place, a 



