TJie Rot in Sheep. 



77 



as well as the generative organs are healthy, but partake of the 

 general pallor which pervades the entire body. 



The liver is the organ chiefly affected, nevertheless it pre- 

 sents characters in some instances the very opposite of those 

 which are met with in others. It is mostly altered in density, 

 shape, size, and colour. Its outline is irregular, and its surfaces, 

 especially the abdominal one, often nodulated by a condensation 

 or shrinking of the substance of the gland in some parts, beyond 

 that of others. Except in cases of early death, it is diminished 

 in size, and changed from its reddish-brown or chocolate 

 hue to a pale or dirty-coloured yellow. Occasionally its sur- 

 face is studded over with small flocculi of lymph and red- 

 coloured spots, which contrast greatly with the yellow clay-like 

 hue which surrounds them. Sometimes these specks are mingled 

 with others of various tints, imparting to the organ a peculiar 

 mottled condition, which led Harrison to remark, in 1804, and 

 Youatt to repeat many years afterwards, that the liver " in some 

 cases is speckled like the back of a toad." 



The general structure of the organ in such cases is condensed, 

 imparting a hard and sometimes gritty feel to the finger. In 

 other instances it is soft, and its normal colour less altered, and 

 well-marked evidences of extensive venous congestion exist. 

 This is denoted chiefly on the abdominal surface, which is both 

 striated and spotted by the enlarged and congested blood-vessels 

 which lie in the course of the main biliary ducts. These ducts 

 are diseased more or less in all cases of long standing. Their 

 coats are thickened and hardened, and their calibre greatly 

 dilated, often to an extent sufficient to admit the end of the 

 finger. They appear as bluish-white lines, more or less con- 

 tinuous, running by the side of the congested blood-vessels, from 

 the central part of the gland towards its outer edge. In some 

 places they are rendered very distinct by projecting above the 

 surface, being here dilated into pouch-like cavities. The coats 

 of the ductus hepaticus, as also of the ductus communis choledo- 

 chus, are not unfrequently so thick as to be upwards of ten times 

 their normal substance, and likewise so hard as to approach the 

 nature of cartilage. 



On slitting up the biliary ducts, especially in the direction of 

 the smaller branches, this hardness is found to increase, and the 

 coats of the ducts to be rough and uneven, arising from cal- 

 careous deposits — phosphate of lime and magnesia — within their 

 tissue. It is this deposit which gives the gritty feel to the sur- 

 face of the liver, and imparts a crackling sound on cutting 

 through its substance. 



Within the dilated ducts we encounter numerous distomata, 

 which are often here and there, and especially in the pouches, so 



