564 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



tioii of the nitrogenous radical of proteid. Traces of dextrose are found in 

 normal urine. 



1 >"\trose is a sweet-tasting- crystalline substance; its solutions rotate polar- 

 ized light to the right. 



Jecorin, a substance found in the liver and the blood, yields dextrose on 

 decomposition. It is said to be a glycose-lecithin. 1 



Glucosainin, C 6 If u < >.X !!._,. — This is yielded as a decomposition product 

 of some proteids. Egg albumin, for example, yields 8 percent, of gluco- 

 sainin. It reduces copper solutions, and has been mistaken for dextrose. 



H H OH 



rZ-Fructose, Levulose, Fruit-sugar, CH 2 OH C C C COCH 2 OH. — 



OHOHH 

 This occurs in many fruits and in honey. It is sweeter than dextrose, and 

 rotates polarized light to the left. It is a product of the decomposition of 

 cane-sugar in the intestinal canal. If levulose be fed. any excess in the blood 

 may be converted into glycogen, and through the glycogen into dextrose. It 

 is possible thus to convert 50 per cent, of the levulose fed into dextrose. 2 

 When levulose is fed to a diabetic patient, it may be burned, though power to 

 burn dextrose has been lost. 3 



H OHOHH 



d- Galactose, CH 2 OH C C C C CHO.— This is found combined 

 OIIH H OH 

 with proteid in the brain, forming the glucoside cerebrin. It is produced 

 together with dextrose in the hydrolytic decomposition of milk-sugar. It does 

 not undergo alcoholic fermentation, at least not with Saccharomyces apiculatus. 

 When fed it may in part be directly burned or in part converted into 

 glycogen. 



The Disaccharides, C 12 H 22 O n . 



These are di-multiple sugars in ether-like combination. To cane-sugar and 

 milk-sugar, Fisher has ascribed the following formulae : 4 



Cane-sugar. M ilk-sugar. 



.CH- — -__ n CH 2 OH 

 n /CHOH U \C 

 u \CIIOH CHOH 



CH O CHOH 



CHOH (II 



CHjOH CH 2 OH 



Dextrose group. Levulose group. 



Cane-sugar, or Saccharose. — Cane-sugar, obtained from the sugar-cane 

 and the beet-root, is largely used to flavor the food, and likewise assumes 

 importance as a food-stuff. On boiling with dilute acids, cane-sugar is con- 

 verted through hydrolysis into a mixture of levulose and dextrose. The same 



1 Bing : Omtralblatt fur Physiologie, 1898, Bd. 12, S. 209. 



7 Minkowski : Archie fur Pathologic und PharmaJeologie, L893, Bd. 31, S. 157. 



3 Loc. cit. * Berichte der deutschen chemischen Gesellschaft, 1894, Bd. 26, S. 2400. 



