DIGESTIVE APPARATTS. 159 



b. Peritoneal hernia or so-called gut tic of the ox. A 

 loop or knuckle of intestine can be felt at the anterior margin 

 of the ileum, retained between the latter and the vestige of the 

 spermatic cord. The doughy, painful swelling, held in posi- 

 tion by the tense cord which is situated anteriorly, is charac- 

 teristic of this condition. 



c. Invagination of the small intestine in cattle. This 

 condition is recognized by the presence of a firm but elastic 

 sausage-like mass in the lumen of the intestine, terminating 

 abruptly posteriorly but insensibly anteriorly where food 

 masses have accumulated. The length of this mass varies 

 with the extent of the invagination. 



d. Torsion of the left layers of the colon in the horse. 

 In this condition the tense mesentery can be felt coursing 

 downward and to the left immediately in front of the entrance 

 to the pelvis and just below the 4th lumbar vertebra. A pull 

 exerted on the mesentery produces symptoms of pain. A sec- 

 ond tense strand can be felt in the umbilical region (a longi- 

 tudinal band of the inferior layer of the colon which courses 

 from left to right). The pelvic flexure has shifted from its 

 normal position. 



II. Enteroliths (stones and concretions in the in- 

 testines) can be detected only when the intestines are compara- 

 tively empty. The presence of large masses of food interferes 

 with their recognition. It is best, therefore, when these are 

 suspected, to free the intestines of their contents with a purge 

 before proceeding with the examination. 



III. Tumors and tuberculous tumefactions of the 

 lymphatics can be recognized only when they have a certain 

 size, e. g., that of a hazelnut, and here too a purge must be 

 given to remove solid fecal masses before exploration begins, 

 otherwise mistakes are easily made. 



c. Percussion of the abdomen. Topographical anatomy. 

 The position of the various portions of the intestinal tract 

 varies considerably according to their degree of fullness ; we 



