The Abdomen 173 



be incarcerated when the peristalsis of the herniated portion of 

 bowel is interrupted, generally through formation of adhesions, 

 and the passage of fecal matter is arrested, but without impairment 

 of circulation. The commonest exciting causes of this condition 

 are constipation and improper foodstuffs. A hernia is said to be 

 strangulated when in addition to incarceration there is interference 

 with circulatipn of the parts. Strangulated hernia may arise from 

 any cause which induces local venous congestion, such as incar- 

 ceration, elastic compression at the neck, inflammatory disturbance 

 in the wall of the retained loop, torsion of the latter, and greatly 

 increased peristalsis. In one fatal case which I saw, the animal 

 had partaken of a very heavy meal a few hours previously, which 

 led to accelerated peristalsis and congestion within the sac, though 

 the hernia had existed undisturbed for four years. Venous con- 

 gestion in a hernia leads to edematous thickening, serous exud- 

 ation, and reactive compression at or near the neck, and thus the cir- 

 culation becomes arrested. Once the nutrition of any portion of 

 the bowel is cut off, microorganisms quickly migrate from the 

 lumen through the wall, and local infectious peritonitis is estab- 

 lished. The fluid bacteria-laden exudate is rapidly absorbed, and 

 the animal dies within a few hours from toxemia. In the case 

 mentioned above 'death occurred at the expiration of thirty-six 

 hours. In many cases of artificial strangulation produced by 

 Tietze death took place in ten or twelve hours. Boenecken found 

 that bacteria commenced to migrate four hours after a loop of in- 

 testine was very tightly ligated. Ziegler made twenty-nine. artificial 

 strangulatiops. In eight of these, bacteria were found within the 

 first ten hours. In three, which had lasted over fifteen hours, 

 bacteria were very plentiful, and consisted of colon bacilli and 

 ordinary pyogenic staphylococci and streptococci, the cocci being 

 the first to migrate. Tietze made seventeen artificial 

 strangulations, and nine of these showed migration in from six 

 to twenty-four hours. In this connection, it is interesting 

 to note that the dog exhibits a remarkable tolerance of simple 

 occlusion by single ligature. Jaffe found that when he ligated the 

 small intestine with a silk ligature the latter cut through little by 

 little until it reached the lumen, the bowel meanwhile becoming 

 reunited by linear cicatrisation without its permeability being at all 

 interfered with. Kirstein had the same experience with rubber 



