610 DIGESTION. 



surface of the small intestine, on the number of arteries distributed to 

 the organ, and on the size of these arteries, he asserted, that the lining 

 membrane of the intestine, at the time of chylification, secretes a juice, 

 which he estimated at the enormous quantity of eight pounds in the 

 twenty-four hours. To this he gave the name succus intestinalis, and 

 assigned it as important a part in chylification as he attributed to the 

 gastric juice in chymification. It is probable, however, that the fluids 

 secreted by the mucous membrane of this portion of the canal resemble 

 those of the rest of the intestinal mucous membrane; and that their 

 main function is that of lubricating the intestine, and of still further 

 diluting the chymous mass. MM. Leuret and Lassaigne endeavoured 

 to procure some of them by making animals, whilst fasting, swallow 

 small sponges, enveloped in fine linen, and killing them twenty-four 

 hours afterwards. Some of these sponges had not gone further than 

 the stomach, and were filled with gastric juice ; others, which had 

 reached the small intestine, had imbibed the succus intestinalis, which 

 was more yellow, and manifestly less acid than the gastric secretion. 

 On attempting to dissolve a crumb of bread in each of these juices, 

 they discovered that the gastric secretion communicated a sour smell to 

 the bread ; but that the intestinal secretion allowed the bread to be 

 precipitated, and dissolved no part of it. From this experiment, it has 

 been concluded, that the succus intestinalis is not a great agent in chyli- 

 fication. The deduction is probably correct; but no weight can be 

 placed upon results obtained in so unsatisfactory a manner ; for it is 

 obvious, that no certainty could exist as to the identity between the 

 gastric and intestinal juices and the fluids found in the respective 

 sponges. 



We have strong reason for believing, that, even if food should escape 

 the action of the stomach, it is capable of being digested in the small 

 intestine. This may be owing to some of the true gastric juice passing 

 into the intestinal canal, and impregnating it; or it may be a similar 

 secretion from follicles seated there. The lining membrane of the small 

 intestine possesses the property of coagulating milk ; and pathological 

 cases occur in which the stomach is, to all appearance, completely dis- 

 organized; yet patients survive so long as to compel us to presume, 

 that digestion must have been effected elsewhere than in that organ. 

 M. Magendie 1 placed a piece of raw meat in the duodenum of a healthy 

 dog. At the expiration of an hour it had reached the rectum, and its 

 weight was found to be but slightly diminished ; the only change ap- 

 peared to be at its surface, which was discoloured. In another experi- 

 ment, he fixed a piece of muscle with a thread, so that it could not pass 

 out of the small intestine. Three hours afterwards, the animal was 

 opened. The piece of meat had lost about half its weight. The fibrin 

 was especially attacked; and what had resisted, which was almost all 

 areolar tissue, was extremely fetid. In experiments by M. Voisin, 2 

 aliment was introduced into the small intestines of animals, in one 

 case masticated and mixed with saliva; in another without any prepara- 

 tion. In a few hours, in the first instance, and after a longer period in 



1 Precis, &c., ii. 113. 2 Nouvel Apergu sur la Physiologie du Foie, etc., Paris, 1833. 



