CARBOHYDRATES. 61 



incompletely broken down is now acted upon completely, and in fact 

 intermediate products are formed which are similar to, if not identical 

 with, those produced by the saliva. The cleavage produced by the pan- 

 creatic diastase is believed to yield finally only maltose. This last, by the 

 action of a particular ferment, gliLcase (also called maltase) , is eventually 

 decomposed into molecules of d-glucose. Here in the intestine the breaking 

 down of cane-sugar also takes place for the most part. By means of the 

 above-mentioned ferments, or at least by similar ones, 1 it is similarly 

 inverted into its two components, dextrose and laevulose (d-glucose and 

 d-fructose). In this way the carbohydrates in the food are prepared 

 for absorption, which sets in as fast as the breaking down of the 

 carbohydrates takes place. 



We must now touch upon the question as to whether the more com- 

 plicated carbohydrates, such as the dextrins, for example, are capable 

 of direct absorption. Under normal conditions these substances are not 

 taken up by the intestine, or at least such products are not met with 

 beyond the intestines in the assimilatory tracts. 2 Cane-sugar and mal- 

 tose can be absorbed directly. They are taken up more slowly than the 

 simpler sugars, and in every case they must suffer cleavage before they 

 are turned over to the blood; for if cane-sugar, avoiding the intestinal 

 canal, is introduced directly into the blood, it suffers no further change, 

 but is eliminated as such in the urine. 3 



The most important result of the successive changes which take place in 

 the intestinal canal as regards the carbohydrates which we have studied 

 up to this point, is the tendency to form by the action of a definite ferment 

 the simplest building material, especially the hexoses, thus giving to the 

 system a uniform material from which it can construct the substances of 

 which the body is composed. It is evident from what has been said that 

 the significance of the alimentary canal and of all the different organs 

 connected with it does not consist solely in transforming the non-diffusible 

 substances, which cannot be absorbed, such as starch, into products 

 which are diffusible. Its task stretches far beyond this single action. 4 

 The molecules which are naturally foreign to the animal organism 

 are destroyed and converted into a homogeneous indifferent material 



1 It is probable that the same ferment does not act upon both maltose and cane- 

 sugar. Cane-sugar is not split up beyond the intestine, while maltose appears as a 

 product from glycogen and is inverted. 



2 Von Mering (Arch. f. anat. und Physiol. 1877, 379, 413) has found substances 

 similar to dextrin in the blood of the portal vein after a diet very rich in carbo- 

 hydrates. It has not been shown whether this is a normal occurrence. 



3 Cf. Fritz Voit: Deut. Arch. klin. Med. 58, 523 (1897). Ernst Weinland: Z. Biol. 

 47, 279 (1905). 



4 Cf. Emil Abderhalden: Zentrb. Stoffwechs. Verdauungskrankheit, 6, No. 24, 

 647 (1904). 



