EXTRACTIVES OF THE BLOOD. 317 



after removal of blood. According to HENRiQUES 1 this increase of the 

 reducing power, at least in dogs, is not due to sugar, but chiefly to jecorin, 

 which substance in normal blood is the cause of more of the reduction 

 than the sugar. It is difficult to judge of the value of many reports 

 as to the amount of sugar and the reducing power of the blood, because 

 the experimenters generally have not considered the presence of a certain 

 quantity of jecorin or conjugated glucuronic acids, or they were unable 

 to detect them. The investigations of ANDERSSON 2 seem to indicate 

 that at least in rabbits, on drawing blood, the fermentable sugar, as well 

 as the non-fermentable " sugar rest/' increases to about the same extent. 3 



The quantity of urea, which, according to SCHONDORFF, is equally 

 divided between the blood-corpuscles and the plasma, is greater on taking 

 food than in starvation (GREHANT and QUINQUAUD, SCHONDORFF) and 

 varies between 0.2 and 1.5 p. m. In dogs SCHONDORFF found in starva- 

 tion a minimum of 0.348 p. m. and a maximum of 1.529 p. m. at the 

 point of highest urea formation. GOTTLIEB obtained much lower results 

 by another direct method, namely, in starvation 0.1-0.2, and after meat 

 feeding 0.28-0.56 p. m. In man v. JAKSCH 4 found 0.5-0.6 p. m. urea 

 in normal blood. The quantity of urea is somewhat increased in fever, 

 and in general in augmented protein metabolism the increased urea for- 

 mation is dependent thereon. A more important increase in the quantity 

 of urea in the blood occurs in a retarded elimination of urea, as in cholera, 

 also in cholera infantum and in infections of the kidneys and urinary 

 passages. After ligaturing the ureters or after extirpation of the kidneys 

 of animals, an accumulation of urea takes place in the blood. 



v. SCHRODER first showed that the blood of the shark was very rich 

 in urea, and the quantity indeed amounted to 26 p. m. BAGLIONI 5 

 has recently shown that this large quantity of urea is of the greatest 

 importance, as the presence of urea in these animals is a necessary life- 

 condition for the heart and very probably for all organs and tissues. 



The blood also contains traces of ammonia. According to HORODYN- 

 SKI, SALASKIN, and ZALESKI, G who worked with the improved NENCKI 

 and ZALESKI method, the quantity in arterial dog-blood was 0.41 milli- 



1 Schenck, Pfluger's Arch., 57; Henriques, Zeitschr. f. physiol. Chem., 23. See also 

 Kolisch and Stejskal, Wien. klin. Wochenschr., 1898. 



2 Bioch. Zeitschr., 12. 



3 In regard to the recent methods for determining sugar in the blood see Bang, 

 Bioch. Zeitschr., 7; Michaelis and Rona, ibid., 7; Oppler and Rona, ibid., 13. 



4 Gre'hant et Quinquaud, Journ. de 1'anatomie et rle la physiol., 20, and Compt. 

 rend., 98; Schondorff, Pfliiger's Arch., 54 and 63; Gottlieb, Arch. f. exp. Path. u. 

 Pharm., 42; v. Jaksch, Leyden-Festschr., I, 1901. 



5 v. Schroder, Zeitschr. f. physiol. Chem., 14; Baglioni, Centralbl. f. Physiol., 19. 



6 Zeitschr. f. physiol. Chem., 35, which also gives the older literature. 



