510 DIGESTION. 



On the introduction of starch even in very considerable quantities 

 into the intestinal tract no dextrose passes into the urine, a condition 

 which probably depends in this case upon the absorption and assimila- 

 tion and the slow saccharification taking place simultaneously. If, 

 on the contrary, large quantities of sugar are introduced at one time, 

 then an elimination of sugar by the urine takes place, and this elimina- 

 tion of sugar is called alimentary glycosuria. In these cases the assimila- 

 tion of the sugar and the absorption do not take place together. 



That quantity of sugar to which we must raise the ingested substance 

 in order to produce an alimentary glycosuria gives, according to HOF- 

 MEiSTER, 1 the assimilation limit for that same sugar. This limit is dif- 

 ferent for various kinds of sugar; and it also varies for the same sugar 

 not only in different animals, but also in different members of the same 

 species, as also in the same individual under varying circumstances. 

 In general it can be said that in regard to the ordinary varieties of sugar r 

 such as dextrose, levulose, galactose, saccharose, maltose, and lactose, 

 the assimilation limit is highest for dextrose and lowest for lactose. It 

 must be admitted that with an overabundant quantity of sugars in the 

 intestinal tract the disaccharides do not have sufficient time for their 

 complete inversion, and this has been directly shown by ROHMANN and 

 NAGANO. It is, therefore, not remarkable that disaccharides, as well, 

 have been found in the urine in cases of alimentary glycosuria. 2 



The investigations of LUDWIG and v. MERING and others have explained 

 how the sugars enter into the blood -stream, namely, that they as well 

 as other bodies soluble in water do not ordinarily pass over into the 

 chylous vessels in measureable quantities, but are chiefly taken up by the 

 blood in the capillaries of the villi and in this way pass into the mass of 

 the blood. These investigations have been confirmed by observations 

 of I. MUNK and ROSENSTEIN 3 on human beings. 



The reason why the sugars and other soluble bodies do not pass over 

 into the chylous vessels in appreciable quantity is, according to HEIDEN- 

 HAIN, 4 to be found in the anatomical conditions, in the arrangement of 

 the capillaries close under the layer of epithelium. Ordinarily these 

 capillaries find the necessary time for the removal of the water and the 

 soJids dissolved in it. But when a large quantity of liquid, such as a 

 sugar solution, is introduced into the intestine at once, this is not possible, 



1 Arch. f. exp. Path. u. Pharm., 25 and 26. 



2 For the literature in regard to the passage of various kinds of sugars into the 

 urine, see C. Voit, Ueber die Glykogenbildung, Zeitschr. f. Biologic, 28, and F. Voit, 

 footnote 2, p. 375. See also Blumenthal, Zur Lehre von der Assimilationsgrenze der 

 Zuckerarten, Inaug.-Dissert. 1903, Strassburg and Brasch, Zeitschr. f. Biol., 50. 



3 v. Mering, Arch. f. (Anat. u.) Physiol., 1877; Munk and Rosenstein, Virchow's 

 Arch., 123. 



4 Pfliiger's Arch., 43, Suppl. 



