SUGAR IN THE BLOOD. 331 



for the total rest reduction. FRANK and BRETSCHNEIDER 1 have, never- 

 theless, shown that the reducing substance or mixture that occurs in the 

 blood-corpuscles, and which does not reduce BERTRAND'S solution, but 

 does reduce BANG'S solution, yields a reduceable sugar on boiling with acid 

 which now reduces BERTRAND'S solution. The corresponding substance 

 in the blood-plasma has a similar behavior. If, as in the experiments 

 of .FRANK and BRETSCHNEIDER, the extent of reduction after acid hydrol- 

 ysis is about the same as the original substance (titrated according to 

 BANG) we cannot here be dealing with dextrins and the nature of this 

 body in question (or mixture) is quite unknown. 



In close relation to what has been given above is the question of 

 " sucre immediat " and the " sucre virtuel " of LEPINE and BouLUD. 2 

 They designate as " sucre immediat " the reduction, calculated as 

 sugar, of the blood immediately after leaving the blood vessels and as 

 " sucre virtuel " the increase in the reducing power brought on in part 

 by allowing the blood to stand after leaving the body, in part by the 

 action of invertase or emulsin at 39 C. and in part by boiling with hydro- 

 fluoric acid. The quantity of " sucre virtuel " in dogs amounts to an average 

 of 70 per cent of the "sucre immediat." The nature of the " sucre virtuel" 

 is not well known; from what was said above we are probably dealing here 

 to all appearances with very different bodies. 



From what has been presented above it can be understood why the 

 exact sugar content of the blood is not known. In consideration of the 

 above mentioned difficulties and sources of error attempts have been made 

 to determine the sugar content of the blood and we will give the results 

 of some of these. 



The quantity of actual sugar in the blood, amounts according to LYTT- 

 KENS and SANDGREN, in man to 0.63, in sheep 0.64, pig 0.82, ox 0.86, 

 horse 0.98, rabbit 2.22, guinea-pig 2.48 and in the cat 2.91 p. m. Small 

 animals with an active metabolism contain more sugar in the blood 

 than larger animals. According to FRANK the amount of sugar in the 

 blood-plasma of man lies between 0.8 and 1.1 p. m. and according to 

 FRANK and COBLINER S it is 1.19-1.26 p. m. in new-born. 



The amount of blood sugar seems to be almost independent of the 

 character of the food. After feeding with large amounts of sugar or dex- 

 trin, BLEILE, nevertheless, has observed a considerable increase in the 

 sugar. The amount of sugar is not only somewhat different with 

 various animals but it also varies with the same animal under different 



1 Zeitschr. f. physiol. Chem., 71 and 76. 



2 Compt. Rend., 137, 144, 147, and Journ de Physiol. et d. Path., 11 and 13. 



3 Lyttkens and Sandgren, Bioch. Zeitschr., 36; Frank and Cobliner, Zetischr. f. 

 physiol. Chem., 70. 



