330 THE BLOOD. 



p. m. sugar. The blood-corpuscles of the ox, sheep, horse, pig, cat and 

 guinea-pig do not contain any sugar according to these last-mentioned 

 investigators. On the contrary the blood-plasma as well as the blood- 

 corpuscles contain a non-fermentable reducing substance. The quan- 

 tity of this in the human blood-corpuscles is 0.6 p. m. according to 

 LYTTKENS and SANDGREN and in the blood-corpuscles of different 

 animals an average of 0.44-0.8 p. m. calculated as glucose. The quan- 

 tity of the non-fermentable bodies in the blood-plasma of the animals 

 investigated by them was 0.3 to 0.5 p. m. 



The quantity of glucose in the blood cannot be exactly determined. 

 As the blood also contains other reducing substances besides glucose the 

 total reduction naturally cannot be used as an exact value for the glucose 

 content; and it must also be added that the different methods do not 

 give uniform results. Thus on using the methods of KNAPP and BANG, 

 which give the total reduction, higher values are obtained than with 

 ALLIHN'S or BERTRAND'S methods, in which the quantity of precipitated 

 cuprous oxide is determined. The polarization method cannot give 

 exact results because of the presence of other optically active substances 

 and objections can also be raised against the fermentation method. 1 

 On using this last method Oiro 2 first observed, and was substantiated 

 later by others, namely BANG and his co-workers, that the blood contained 

 non-fermentable bodies which reduced KNAPP'S (and also BANG'S) solu- 

 tion. The remaining reduction "rest reduction" after the fermenta- 

 tion cannot be detected according to BERTRAND'S titration method. 



The nature of this reducing but not fermentable substance occurring 

 in the plasma as well as in the blood-corpuscles is not known. The 

 assumption of JACOBSEN, BING, and HENRIQUES S that this question- 

 able substance is jecorin or lecithin sugar does not have sufficient founda- 

 tion, and the question of the identity with jecorin is doubtful and is con- 

 nected with the question as to the existence of jecorin at all. The 

 conjugated glucuronic acids have also been considered and according 

 to the investigations of MAYER, LEPINE and BOULUD 4 they occur in 

 blood and originate in the form-elements. For these assumptions we 

 do not have sufficient support, and especially we have no explanation 



1 In regard to methods see Bang, Der Blutzucker, Wiesbaden, 1913 which also 

 describes a new method suggested by him for the determination of sugar in very small 

 amounts of blood. 



2 Pfluger's Arch., 35. 



3 Jacobson, Centralbl. f. physiol. 6; Bing, Skand. Arch. f. physiol., 9; Henriques, 

 Zeitschr. f. physiol Chem., 23. See also P. Mayer, Bioch. Zeitschr., 1 and 4. 



4 Mayer, Zeitschr. f. physiol. Chem. ,'32; Lepine and Boulud, Compt. Rend., 133, 

 135, 136, 138, 141 and Journ. de Physiol., 7 (cited from Bioch. Centralbl., 4, page 421). 



