296 THE BLOOD. 



According to the researches of KOSSEL and of LILIENFELD 1 the blood- 

 plates consist of a chemical combination between protein and nuclein, 

 and hence they are also called nuclein-plates by LILIENFELD, and are 

 considered as derivatives of the cell nucleus. It seems certain that the 

 blood-plates have some connection with the coagulation of blood. The 

 views on this question, and especially in regard to the manner in which 

 these plates act in coagulation, are unfortunately very divergent. 



III. THE BLOOD AS A MIXTURE OF PLASMA AND BLOOD CORPUSCLES. 



The blood in itself is a thick, sticky, light or dark red liquid, opaque 

 even in thin layers, having a salty taste and a faint odor differing in 

 different kinds of animals. On the addition of sulphuric acid to the blood 

 the odor is more pronounced. In adult human beings the specific gravity 

 ranges between 1.045 and 1.075. It has an average of 1.058 for grown 

 men and a little less for women. LLOYD JONES found that the specific 

 gravity is highest at birth and lowest in children when about two years 

 old and in pregnant women. The determinations of LLOYD JONES, 

 HAMMERSCHLAG, 2 and others show that the variation of the specific 

 gravity, dependent upon age and sex, corresponds to the variation in the 

 quantity of hemoglobin. 



The determination of the specific gravity is most accurately done by 

 means of the pyknometer. For clinical purposes, where only small 

 amounts are available, it is best to proceed by the method as suggested 

 by HAMMERSCHLAG. Prepare a mixture of chloroform and benzene of 

 about 1.050 sp. gr. and add a drop of the blood to this mixture. If the 

 drop rises to the surface then add benzene, and if it sinks add chloroform. 

 Continue this until the drop of blood suspends itself midway and then deter- 

 mine the specific gravity of the mixture by means of an areometer. This 

 method is not strictly accurate and must be performed quickly. In 

 regard to the necessary details refer to ZUNTZ and A. LEVY. 3 



The reaction of the blood is alkaline toward litmus. The quantity 

 of alkali, calculated as Na^COs, in fresh, non-defibrinated blood from the 

 dog, horse, and man, is, according to LOEWY, 4.93, 4.43, and 5.95 p. m. 

 respectively. According to STRAUSS the average for normal human blood 

 may be calculated as about 4.3 p. m. Na 2 COs. Quantities below 3.3 

 p. m. and above 5.3 p. m. are, according to him, to be considered as 



1 In regard to the literature of the blood-plates, see Lilfenfeld, Arch. f. (Anat. u.) 

 Physiol., 1892, and " Leukocyten und Blutgerinmmg," Verhandl. d. physiol. Gesellsch. 

 zu Berlin, 1892; and also Mosen, Arch. f. (Anat. u.) Physiol., 1893, and Maly's Jahres- 

 ber., 30 and 31. 



2 Lloyd Jones, Journ. of Physiol., 8; Hammerschlag, Wien. klin. Wochenschrift, 

 1890, and Zeitschr. f. klin. Med., 20. 



3 Zuntz, Pfliiger's Arch., 66; Levy, Proceed. Roy. Soc., 71. 



