412 THE LIVER. 



which the sugar was formed. The formation of sugar from protein is 

 now generally considered as positively proved. 



DAKIN 1 has found with experiments with phlorhizinized dogs that 

 serine, cysteine, proline, ornithine and arginine yield abundant sugar in 

 glycosuric animals. Valine, leucine, isoleucine, lysine, hisfcidine, phenyl- 

 alanine and tryptophane gave relatively little sugar or none at all. 

 The ammo-acids with straight chains (with the exception of lysine) give 

 sugar while those with branched chains do not. Proline is the only 

 cyclic amino-acid, which yields abundance of sugar. Arginine is the 

 only one with more than five carbon atoms which yields sugar and the 

 sugar comes in this case from the ornithine components. 



If we assume a formation of sugar from fat, we must differentiate 

 between the two components of neutral fats, that is, between the glyc- 

 erin and the fatty acids. A formation of sugar from glycerin can 

 be considered as proved by the investigations of CREMEB, and especially 

 those of LUTHJE 2 and in the following we will discuss only the forma- 

 tion of sugar from the fatty acids. 



The formation of sugar from fat seems to occur in the plant king- 

 dom, and as the chemical processes in the animal and plant life are in 

 principle the same, it makes the possibility of a sugar formation from 

 fat very probable. Such an origin of sugar in the animal body is accepted 

 by many investigators, especially by PFLTJGER and several French observ- 

 ers, among whom \ve must specially mention CHAUVEAU and KAUF- 



MANN. 3 



When food as free from carbohydrate as possible is taken, the quo- 

 tient D:N is high, i.e., higher than 8, as well as when the quantity of 

 sugar is so large that it cannot be accounted for by the calculated 

 protein (and carbohydrate) metabolism, then if the observations are 

 otherwise free from error we can admit of a formation of sugar from fat. 

 Several such cases of diabetes in man have been published (RUMPF, 

 ROSENQVIST, MOHR, v. NOORDEN, ALLARD, FALTA and co-workers and 

 others), and also in animals (HARTOGH and ScnuMM 4 ). Although these 

 researches are not fully conclusive, still certain of them indicate a prob- 

 able formation of sugar from fat. We also have several conditions which 



1 Journ. of biol. Chem., 14, 321. 



2 Cremer, Sitzungsber. d. Ges. f. Morph. u. Physiol. Miinchen, 1902; Luthje, Deutsch. 

 Arch. f. klin. Med., 80. 



3 Kaufmann, Arch. f. Physiol. (5), 8, where Chauveau's work is cited. 



4 Rumpf, Berl. klin. Wochenschr., 1899; Rosenqvist, ibid.', Mohr, ibid., 1901; v. 

 Noorden, Die Zuckerkrankheit, 3. Aufl. Berlin, 1901; Allard, Arch. f. exp. Path. u. 

 Pharm., 57; Falta and co-workers, Zeitschr. f. klin. Med., 66; Hartogh and Schumm, 

 Arch. f. Path. u. Pharm., 45. See also the works of O. Loewi, ibid., 47, and Lusk, 

 Zeitschr. f. Biologic, 42. 



