362 DISEASES OF* THE SHEEP. 



to its rapid expenditure when the utmost exertion of strength 

 and speed are required from him. In the ox the lungs are 

 less developed ; yet this animal is used in some countries as 

 a beast of burden, and employed in Great Britain in agricul- 

 tural labor ; the lungs, therefore, are of considerable size, 

 and the liver, although much larger than in the horse, is re- 

 stricted in its growth. In sheep little exertion of strength 

 or speed is required ; and the lungs are smaller compared 

 with the size of the animal. The liver is proportionally 

 larger : it is about one twentieth part of the whole weight of 

 the animal, or nearly double the proportionate size which it 

 is in the human being. 



The liver of the sheep differs little in form and situation 

 from that of the ox. It is placed in the anterior part of the 

 abdomen, between the maniplus and the diaphragm. It has 

 but two principal lobes, separated by a triangular scissure, 

 through which, in the pregnant ewe, the umbilical vein of 

 the foetus passes. Its office is to receive the blood that is 

 returned from the intestines ; to separate from the blood, or 

 to secrete by means of it, a fluid termed bile, and to transmit 

 the remaining part to the lungs, there to undergo the usual 

 process of purifaction, and be changed to arterial blood. 

 The vessel to which the bile is first conveyed is the gall- 

 bladder ; where it is stored up for future use, and perhaps 

 undergoes some change. From the gall-bladder it is con- 

 veyed to the first intestine, the duodenum, either in a con- 

 stant but slow stream, or probably in a larger stream while 

 the work of digestion is going on ; the supply from the gall 

 bladder, and probably the secretion from the liver, being 

 stopped at other times. A little before this duct reaches the 

 intestine, it is joined and perforated by the duct from the 

 pancreas. The fluid from the pancreas is mixed with that 

 from the liver, and the compound flows on to the duode- 



This disease is classed'among those of the liver, because, 

 except when the animal dies perfectly worn out by the mal- 

 ady, the most striking and the supposed characteristic mis- 

 chief is found in this organ. 



Happily Jor the American farmers, this destructive mala- 

 dy is, comparatively, of unfrequent occurrence in their 

 flocks T but in Great Britain, on the authority of Mr. Youatt, 



