DOES BLOOD CONTAIN OTHER CARBOHYDRATES? 209 



blood cake for twenty-four hours with hydrofluoric acid. 

 They must in this case certainly be dealing with some glucos- 

 amine compounds, connected with the structural composition 

 of the blood proteids (and too, in that of other proteins) 

 separable by hydrolytic cleavage from the latter ; these are 

 not, however, a part of the true blood sugar. 52 



Contrary to the statement that a fourth or more of the 

 blood sugar which is concerned in normal reduction experi- 

 ments is in the form of a non-fermentescible rest-sugar, 53 no 

 such substance could be recognized by estimating the reduc- 

 ing power of blood by Bertrand's method after fermentation 

 either in the blood or in the serum. 54 



It will be readily realized that the blood at times may con- 

 tain not inconsiderable quantities of maltose and glycogen 

 (carbohydrates which may decidedly increase the reducing 

 ability of the blood after fermentative cleavage) , 55 It seems 

 doubtful, however, whether these substances are sufficient 

 to fully explain the observations recorded in reference to 

 "virtual sugar. " In the author's opinion it is more prob- 

 able that in this we have to do with phenomena of a physical- 

 chemical nature, which we know very well are able to 

 markedly influence the conditions of solubility of sugar. 

 Occasion has been taken in a previous lecture (v. Vol. I of 

 this series, p. 170, Chemistry of the Tissues) to call atten- 

 tion to the enveloping phenomena which gave rise to the 

 mistaken assumption of a chemical combination between 

 lecithin and glucose ("jecorin"). 56 One may easily im- 

 agine how a part of the sugar in the blood in some such 



62 Literature upon the Carbohydrate Groups of Proteins : L. Langstein, 

 Ergebn. d. Physiol., 1, 91-98, 1902; Monatshefte f. Chem., 26, 531, 1905. 



63 J. G. Otto, Pfluger's Arch., 35, 474, 1885; N. Anderson (Lund), Biochem. 

 Zeitschr., 12, 1, 1908. 



M E. Frank and A. Brettschneider, Zeitschr. f. physiol. Chem., 71, 157, 1911. 

 M Literature : A. Magnus-Levy, Handb. d. Biochem., 4' 318-319, 1909; 



E. Frank and Brettschneider, Zeitschr. f. physiol. Chem., 76, 226, 1911; 



F. Spallitta (Palermo), Arch. ital. de Biol., 53, 356, 1910. 



00 Note the doubt expressed by P. Mayer (Salkowski's Lab.), Biochem. 

 Zeitschr., 4, 545, 1908, as to the chemical individuality of jecorin. 

 14 



