198 DIGESTION OF CARBOHYDRATES 



sugars generally and certainly the high-molecular carbohy- 

 drates undergo complete cleavage before they gain access to 

 the blood-stream. 11 



This rule is not invalidated by the fact that after a diet 

 rich in carbohydrates, as pointed out by v. Mering, Otto and 

 others, dextrin-like carbohydrates may gain access in the 

 portal blood, 12 and that they are recognizable in small 

 amount in urine normally, but to a much greater extent in 

 diabetes. 13 



Dilution of a Sugar Solution in the Intestine. According 

 to the investigations of London carbohydrate absorption 

 in the stomach is of little importance. If a concentrated 

 sugar solution be introduced into the small intestine sugar 

 is absorbed, and at the same time water is given off into the 

 intestinal lumen until the degree of sugar concentration in 

 the latter is reduced to about 6 or 8 per cent., after which at 

 this dilution the resorption proceeds rapidly. 14 From 

 researches published from Eohmann's laboratory, the re- 

 sorption of glucose from the intestine reaches its relative 

 maximum at a concentration corresponding with the osmotic 

 pressure of the blood serum. 15 



The author would next pass to the consideration of one of 

 the problems relating to the fate of carbohydrates in the di- 

 gestive tract, which is at present of special interest to him, 

 the problem of digestion of cellulose. 



Disappearance of Coarse Vegetable Fibres from the 

 Digestive Tract. In view of the great quantities of cellulose 

 which vegetarians ingest with the food the question naturally 

 presents itself as to whether and how this can physiologically 

 be made use of in the body. Even the early investigations of 



11 H. Bierry, Biochem. Zeitschr., 44, 402, 405, 426, 1912. 

 " J. Munk, Ergebn. d. Physiol., 1, 306, 1902. 



13 K. v. Alfthan, Ueber dextrinartige Substanzen im diabetischen Harne, 

 Helsingfors, 1904. 



14 E. S. London and W. W. Polowzowa, Zeitschr. f. physiol. Chem., 56, 513, 

 1908; 57, 529, 1908.. 



K. Omi (Rohmann's Lab., Breslau), Pfliiger's Arch., 126, 428, 1909. 



