FORMATION OF SUGAR. 123 



or glucose. This very rarely depends upon sugar having been 

 present in the food ; for it is precisely after saccharine food has 

 been taken^ that we most rarely find this substance in the small 

 intestine, and then only in its upper part ; the sugar introduced 

 into the stomach is unquestionably resorbed from thence, being a 

 readily soluble substance. On the other hand, the sugar found 

 in the small intestine, and sometimes even in the large intestine, 

 owes its origin to the action of the pancreatic juice on starch an 

 action which, with the co-operation of the intestinal juice, is pro- 

 longed to almost the end of the intestinal canal. 



In seven cases in which Frerichs fed animals with milk, he 

 could only twice find sugar in the jejunum. 



In the aqueous extract of the contents of the small intestine, 

 and occasionally in that obtained from the contents of the large 

 intestine, we find a protein-body coagulable by heat, and usually 

 precipitable by acetic acid, always, however, occurring in small 

 quantity. This minute quantity of coagulable matter might well 

 be regarded as a product of the digestion of some protein-body 

 that had been taken as food; for the peptones, which are so 

 readily soluble, are for the most part resorbed from the stomach 

 itself; the digestion of the protein-bodies which pass undissolved 

 from the stomach into the small intestine, cannot be very consider- 

 able in the small intestine after the access of the bile. Moreover, 

 the pancreatic juice, to judge by the amount of its secretion, can- 

 not yield any great contribution to the coagulable matter of the 

 aqueous extract of the intestinal contents. But we also invariably 

 find some coagulable albuminous matter after the use of vegetable 

 food poor in protein-bodies, or even of non-nitrogenous food. 

 Hence its sources can only be sought in the exudation of a larger 

 or smaller quantity of albumen from the blood-vessels, in con- 

 sequence of endosmotic relations. 



In four cases in which fasting horses or dogs were fed for two 

 days on balls of starch, and were then killed, I found by no 

 means a very small quantity of coagulable matter in the 

 aqueous extracts of the contents of the jejunum and ileum. In 

 the discharges from the ileum in the above mentioned case of in- 

 testinal fistula, coagulable matter was always found after the use 

 of water-gruel and other slightly nitrogenous food, and in such 

 quantity that it could not possibly be referred to the protein 

 contained in the bread, groats, &c. We need hardly mention 

 that the precipitate formed on boiling must always be treated with 

 acids and other reagents ; for in the watery extract of the intestinal 

 contents, especially in that obtained from the colon, we not un- 



