ii EXTEKEAL DIGESTIVE SECKETIONS 129 



to Budge, extirpation of the caeliac plexus causes increase of 

 intestinal peristalsis, with increased secretion of succus entericus. 

 Moreau's results are more important (1868). After making an 

 intestinal loop, he cut the mesenteric nerves which accompany 

 the vessels of the loop, and at once, or shortly after, saw an extra- 

 ordinary amount of juice secreted in the loop, but not in the 

 contiguous parts of the intestine in which the nerves were intact. 

 This excessive secretion may amount to T \- of the body-weight ; it 

 lasts for several hours, becomes less after 4 to 5 hours, and only 

 ceases after 24 hours. The secretion is at first a clear liquid, 

 which presently becomes clouded with flocculi of mucus. Some- 

 times it looks milky, and it contains large quantities of detached 

 epithelial cells. 



This enormous formation of intestinal juice (which has the 

 same properties as the normal secretion collected in the loop of 

 Vella) is not explained by simple paralytic dilatation of the vessels. 

 We must assume that the phenomenon depends on lapse of control 

 by special nerves, of the secretory processes of the epithelia. 

 Since the secretion is in this case the effect, not of excitation, but 

 of severance of the nerves, we are forced to assume that the latter 

 inhibit the intestinal secretion, i.e. normally serve to keep it in 

 bounds by their tonic action. Nothing similar has, however, been 

 produced on stimulating the nerves to these glands. Moreau's 

 phenomenon plainly recalls 01. Bernard's discovery of paralytic 

 secretion for the submaxillary gland, and presents the same 

 difficulties of interpretation. 



According to the supporters of Bayliss and Starling's theory 

 (see p. 90 et seq.), the intestinal secretion, also, is due to the produc- 

 tion by the duodenum of secretin, which, on absorption and circula- 

 tion in the blood, comes into contact with the intestinal epithelia 

 of the gut, and excites them to secrete. This theory rests on 

 certain observations on secretion in a Vella's loop after the 

 injection of secretin. We have already pointed out the inadequacy 

 of these observations, and it is unnecessary to recapitulate the 

 objections in reference to intestinal secretion also. 



According to Delezenne and Frouin, the succus entericus, after 

 undergoing the action of acids in the intestinal cavity, is reabsorbed 

 and excites secretion in other parts of the intestine. They 

 observed that succus entericus, acidified with hydrochloric acid 

 and subsequently neutralised and injected into the vein, excites 

 an abundant secretion. Moreover, in a dog provided with two 

 Thiry's intestinal fistulae, the introduction into one of the 

 fistulae of substances that excite secretion (hydrochloric acid, ether, 

 water) produced secretion in the other fistula also. This secretory 

 action at a distance is determined, according to Frouin and 

 Delezenne, not by the propagation of secretory stimuli by nervous 

 paths, but by the action of the reabsorbed succus entericus. 



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