236 PHYSIOLOGY CHAP. 



tract was comparatively short, but included the last portion of the 

 ileum. On the other hand, 4 dogs, in which a part of the small 

 intestine of varying lengths (60-110 cm.) had been reversed 15 cm. 

 above the ileo-caecal valve, survived for some time (5, 12, 15, 18 

 days). At the autopsy all these animals exhibited fusiform 

 distension of the intestine, the centre of which corresponded to the 

 upper suture. 



More recently, two German surgeons, Enderlen and Hesse, on 

 repeating the same experiments with 3 dogs, arrived at different 

 results. Two of their dogs lived 73 days; another was killed 

 after 49 days. On faradic stimulation the inverted loop showed 

 peristaltic waves in the bucco-anal direction, i.e. in an opposite 

 (antiperistaltic) direction to that normal to the inverted loop. 

 They concluded that although normally there are no antiperis- 

 taltic movements in the gut, the reversed loop is capable of 

 adapting itself to the new conditions, and of inverting the direction 

 of its movements. 



In Kirstein's 2 dogs (one of which was killed after 7 

 weeks, the other after 4 months) the important fact was 

 observed of a considerable thickening of the muscles of the 

 intestine, confined to the upper half of the dilated tract, to which 

 the lower end of the reversed loop was sutured. It should also be 

 noted that the dog killed after 4 months (although its nutrition 

 and defaecation were almost normal) was beginning to exhibit 

 emaciation, which might conceivably have continued until, like the 

 other dogs, it perished of marasmus, had Kirstein not been in 

 such haste to make his post-mortem examination. 



Further experiments are needed before we can adequately 

 explain these phenomena. It seems to us, however, more than 

 probable that the fusiform dilatation of the intestine, as described 

 above, is the effect of accumulation there of the ingesta, secretions, 

 and intestinal gases, due to the resistance opposed by the reversed 

 loop, with its ascending peristaltic movements, to the passage of the 

 intestinal contents. This resistance (if the inverted part does not 

 adapt itself by reversing the normal direction of its movements) 

 can only be overcome by exaggerated descending peristalsis of the 

 upper part, as shown by the hypertrophy of its muscles, owing to 

 which there is passive dilatation of the first part of the reversed 

 loop, in which hypertrophy of the muscular coat is altogether 

 absent. 



It has been attempted, from cases of intestinal fistula in man 

 and dogs, to determine the speed and force of the intestinal- 

 peristaltic movements ; but the results were very variable, as we 

 should expect on taking into account the different degrees of reple- 

 tion, varying character of the ingesta, and dissimilar strength of the 

 several parts of the gut. One important fact alone results from 

 these experiments, and harmonises perfectly with the anatomical 



