DISEASES OF SHEEP. 



Phis examination of the slioop will lead us to the principal and 

 r /imary seat of the disease, nanieiy, the liver. What is the cause of 

 nis atTeciioM of the liver is another question, and a very important 

 .ne. There is a dispute which no one has yet settled, whether this 

 hike-worm is the cause or the constujuence of the disease. I am 

 rery much inclined to thirds that it is tlie consequence, although it 

 nay and does much atrrrravate the disease. These parasitical ani- 

 nals, both in the animal and vegetable kingdoms, fasten upon a part 

 hat is diseased, or the vitality of which is weakened. 



Another disputed point is the source of these flukes. Are the eggs 

 taken up in the herbage] Does some insect or fly, that is a fluke in 

 Dne part of its existence, lay its eggs on plants growing in wet pas- 

 tures, or by the side of stagnant water] We have no proof of this, 

 tnd we never saw the fluke in any other form. Therefore, it is use- 

 less to dispute about that which cannot be resolved. The most pro- 

 bable thing, however, is, that the eggs, whence the fluke is produced, 

 are, like the eggs of many animalcula, floating in the air, so small 

 and pellucid as to be invisible to us ; that they are inhaled with the 

 breath, or received with the food, but only find a proper nest, a proper 

 place to be hatched into life, in the liver of the sheep labouring under 

 the rot. 



These flukes are occasionally found in the livers of almost every 

 domestic quadruped, and so far as it has hitherto appeared, they are 

 in all of them connected with disease. 



Well, then, what is the cause of this affection of the liver? It is 

 evidently connected with moisture, altliough it may be difficult to 

 trace the connexion between this moisture and a diseased liver. 



It is, however, proper to observe, that the eggs of flukes have been 

 found in countless numbers in the biliary ducts on examining the 

 liver of a cothed or rotten sheep in the months of A])ril, May, or June ; 

 and it is considered by respectable authority, that these eggs are 

 passed into the bowels, evacuated w^ith the dung, and, their vitality 

 being preserved by the sun and moisture, they are swallowed with 

 the grass by sound animals, who thus become infected. Whereas 

 if the eggs had fallen on dry land, their vitality would be destroyed. 

 Although it appears reasonable enough that the infection is produced 

 through the medium of the stomach, yet it would be expected, if the 

 above theory were entirely correct, that by keejti ng sheep from rot- 

 ting land for several years, such land would cease to produce the 

 Jisease, from the absence of the eggfs; which, however, is not found 

 o be the case. It is therefore probable that there are other sources 

 from w'hich the errgs of flukes are derived, besides the dung of sheep. 



The history of the rot is plain enough here. It prevails, or rather 

 it is foimd only, in boggy, poachy ground. On upland pasture, w ith 

 R light sandy soil, it is never seen ; and in good sound pasture, in a 

 lower situation, it is only seen when, from an unusually wet season, 

 *hat pasture has become bogoy and poachy. It is also proved to 

 •Jeniunstration, that land that has been notoriously rotting grc and, has 



