78 



The Rot in Sheep. 



closely packed as to block up the passage. Their number, 

 however, is liable to great variation, and, as has been rightly 

 asserted, is not always in proportion to the extent of the struc- 

 tural changes in the liver. No doubt secondary causes play 

 a not unimportant part in these changes, and so also does time ; 

 but nevertheless the lesions of the liver are upon the whole so 

 peculiar that, were no entozoa present, a pathologist would 

 ascribe them to the prior existence of flukes, and to none other. 

 Distomata will often quit the liver by passing into the intestinal 

 canal through the ductus communis choledochus, especially when 

 the entire structure of the organ has become impaired. Their 

 food is the bile, and the more this is changed in quality, which 

 is always in proportion to the extent of the structural disease of 

 the liver, the less suitable it will be for their support. Besides 

 this, these entozoa, in common with all other creatures, have 

 their ordinary limit of life, and, be this what it may, it is not 

 unreasonable to suppose that their approaching dissolution may 

 at times possibly be an additional reason for their quitting the 

 biliary ducts for the intestinal canal. 



We have frequently met with dead flukes in the intestines, 

 and sometimes in the liver, and occasionally have found them 

 forming the nuclei of biliary concretions. One remarkable 

 instance of this was a few years since brought to our notice, 

 where the concretion was as large as an ordinary hen's egg, 

 and when broken up was found to contain about a dozen dead 

 flukes. It was lying in a pouch-like cavity of one of the 

 biliary ducts. 



Another reason must be named as explanatory, perhaps, of the 

 cause of but few flukes being met with in the biliary ducts, when 

 the extent of the lesions of the liver does not bear a comparison 

 with their number, viz. that on the death of the animal, whose 

 body they inhabited, taking place, they leave their original loca- 

 tion, as if making an effort to escape from their own consequent 

 death. Many of the intestinal worms, the ascaris lumbricoides 

 and megalocephala, the tcenice, trichocephali, &c, comport them- 

 selves in this manner ; and in so doing they often form large 

 masses or knots in a part of the intestinal canal distant from 

 their ordinary dwelling. Lumbricoid worms have been known, 

 under such circumstances, to enter the stomach, and even to pass 

 up the oesophagus into the mouth to effect their escape. We 

 have occasionally found them crowded into the duodenum, so as 

 to literally block it up throughout the greater portion of its 

 length from having been arrested in their effort to enter the 

 stomach through the pylorus. Two remarkable specimens of 

 this kind are preserved in the Museum of the Royal Veterinary 

 College, one from the horse and the other from the pig. 



