THE DIGESTIVE SYSTEM. 265 



and a separation of its epithelium on the surface of the 

 cakes are neither of them solely due to inflammation or 

 impaction. The condition of the contents of the omasum 

 post mortem depends very much on previous conditions of 

 the viscus and the nature of the diet. If the organ has been 

 inactive food material will accumulate in it^ as in any other 

 inert saccular dilatation of the oesophagus, and that to a 

 very great extent, and the matter accumulated will not 

 be subjected to such firm muscular contraction as is 

 always supposed to occur and make the contents hard. 

 Rigor mortis, on the contrary, tends to bring about this 

 contraction, and, no doubt, solely on this, a dry condition 

 of the contents of the omasum often depends. Never- 

 theless, we must allow that impaction of this organ occurs 

 as a result of the consumption of indigestible materials, 

 such as autumn grass which has been allowed to remain 

 in the pasture until spring, straw, and washed hay, also 

 the coarse and indigestible herbage sometimes found in 

 old pasture with many trees about. Astringent herbage, 

 as heath, has a somewhat similar effect. 



The Symptoms found in these cases are : — ^At first the 

 frequent passage of small quantities of hard glazed faeces, 

 succeeded by obstinate constipation. The patient stands 

 persistently, and can scarcely be moved. Its pulse is 

 hard and frequent. It is dull, and evidently suffering from 

 acute abdominal pain. There is the grunt indicative of this, 

 which has caused the disease to be mistaken for pleuro- 

 pneumonia. General signs of disorder are also present. 

 Later, the brain generally becomes affected, and the sym- 

 ptoms are considerably modified, there being muscular 

 tremors over the surface of the body, staring condition of 

 the eyes, which are insensible to light, staggering gait, 

 terminating in paralysis, or wild rushing about, pro- 

 trusion of the tongue, which becomes much swollen. 

 Tympany often occurs as a complication. The urine, 

 too, is sometimes mingled with blood. Youatt has a 

 theory that the hard distended omasum pressed on vena 

 portae against the liver, and thus prevented return of 

 blood from the intestines, which brings about a determina- 



