Colic in Solipeds from Verminous Embolism. 219 



by the presence of the worms, tends to undergo retrogressive 

 changes notably fatty degeneration, to which germs brought on 

 the worms or in their alimentary canals contribute. This to- 

 gether with the movements of the parasites tends to break up 

 the mass, and minute portions are washed on into the different 

 smaller vessels. Soon these reach divisions which are too small 

 to admit them, which are accordingly occluded and the circula- 

 tion through them abolished. The presence of microbes as well 

 as fibrine contributes to cause further coagulation, more absolute 

 embolism and arrest of the circulation. 



It is further alleged that the sexual instinct in the summer 

 months (May to August) leads the worms to leave the aneurisms, 

 to pass through the smaller divisions to the caecum or colon where 

 alone full sexual evolution is possible. In these migrations they 

 cause the thrombosis of the smaller trunks and determine the 

 verminous congestion of the bowels which are especially com- 

 mon in these months. 



Disturbances of the Intestinal Circulation. As these usually 

 occur in the lines of distribution of the anterior mesenteric artery 

 a knowledge of its divisions and their destination and anastomoses, 

 is essential to an intelligent understanding of the pathogenesis 

 and lesions. As first pointed out by I^ecoq the anterior mesen- 

 teric artery is divided into three primary bundles : (a) a left of 

 15 to 20 trunks which are destined to the small intestine ; (b) a 

 right which gives off csecal branches, one to the double colon, 

 and one to the ileum to anastomose with the last trunk of the left 

 bundle ; and (c) an anterior which gives one branch to the second 

 division of the double colon and anastomoses with the colic branch 

 of the right bundle at the pelvic flexure ; and a second branch to 

 the floating colon to anastomose with the posterior mesenteric 



artery. 



The divisions of the left bundle anastomose so freely with each 

 other in the mesentery and immediately above the intestine that 

 the blocking of any one branch cannot entirely arrest the circu- 

 lation in the corresponding part of the intestine. It may how- 

 ever produce a partial local stagnation in the vessels of a short 

 loop of intestine, resulting in oedematous infiltration and thicken- 

 ing with resulting induration and stricture of the gut. Chronic 

 and permanent lesions are produced by such blocking, but only 



