THE CHEMISTRY OF THE ANIMAL BODY. 563 



(4) Only trioses, hexoses, and nonoses are capable of alcoholic fermenta- 

 tion. 



Synthesis of the Glucoses. — Formose (see p. 533) may be purified by means of 

 phenylhydrazin as above, so that pure /-fructose is obtained ; this treated with 

 sodium amalgam yields /-mannite, which on oxidation is converted into /-man- 

 nonicaeid ; this last is separated by a strychnin salt into its two components ■ 

 the rf-mannonic acid is divided and one part treated with hydrogen, with result- 

 ing d-mannose, which, as has been shown above, is convertible into (/-fructose 

 or ordinary fruit-sugar ; the second part of the c/-mannonic acid treated with 

 chinolin is transformed through change in configuration into its isomer, 

 (/-gluconic acid, which on reduction yields (/-glucose, or ordinary dextrose. 

 This shows the preparation of the common sugars from their elements. The 

 transformation of levulose into dextrose is especially to be noted, since it takes 

 place in the body. 



K H OHH 



(/-Glucose, Dextrose, Grape-sugar, CH 2 OH C C C C CHO.— 



OH OH H OH 

 This is the sugar of the body. It is found in the blood and other fluids and in 

 the tissues to the extent of 0.1 per cent, and more, even during starvation. The 

 principal source of the dextrose of the blood is that derived from the digestion 

 of starch, and also of cane-sugar, in the intestinal tract. Dextrose is likewise pro- 

 duced from proteid, for a diabetic patient fed solely on proteid may still excrete 

 sugar in the urine. Minkowski 1 finds that in starving dogs after extirpation 

 of the pancreas the proportion of sugar to nitrogen is 2.8 : 1. The same ratio 

 has been shown to exist in phlorhizin diabetes in fasting rabbits 2 and goats 3 

 when the drug is frequently administered. After frequent dosage of phlorhizin 

 to fasting, meat-fed, or gelatin-fed dogs, the ratio dextrose : nitrogen approxi- 

 mates 3.75 : 1. Since 1 gram of N in the urine corresponds (neglecting the faecal 

 N) to 6.25 grams of proteid destroyed, therefore, 3.75 grams ot sugar must 

 have arisen from <>.25 grams of proteid (including gelatin). In other words, 

 there has been a production from the proteid molecule of 60 per cent. 

 of dextrose, which contains nearly 60 per cent, of the physiologically avail- 

 able energy of the proteid consumed. 4 A similar large excretion of dextrose 

 has been noted in cases of human diabetes mellitus.* 



In pancreas diabetes the pancreas may perhaps manufacture a ferment 

 which, supplied from the lymph of the pancreas'' to the tissues, becomes the 

 first cause of the decomposition of dextrose, and in whose absence diabetes 

 ensues. Excess of dextrose in the body is stored up, especially in the liver- 

 cells, as glycogen, which is the anhydride of dextrose ) the glycogen may be 

 afterwards reconverted into dextrose. The presence of sugar in the body in 

 starvation, even when little urea may be detected there, shows the readier excre- 



1 Arehivfiir Exper. Paihologie wnd Pharmakologie, L893, Bd. 31, 8. 85. 



a Lusk : Zeitachriftfiir Biologic, 1898, Bd. 36, S. 82. i busk: Unpublished. 



* Reilly, Nolan, and Lusk: American Journal of Physiology, 1898, vol. i. j>. 895. 



s Kmnpf: Berliner Minischer Wbchenschrift, 1898, Bd. 24, Heft 43. 



■ Biedl : Centralbatt fur Physiologic, 1898, Bd. 12,8.624. 



