QUANTITATIVE COMPOSITION OF THE BLOOD. 313 



several investigators, such as EYKMAN, BIERNACKI and HE DIN, l must 

 be especially mentioned. In regard to this as well as to the method 

 of St. BUGARSKY and TANGL, which is based upon a difference in the 

 electrical conductivity of the blood and the plasma, and STEWART'S 2 

 colorimetric method, we must refer to the original publications. 



For clinical purposes the relative volume of corpuscles in the blood may 

 be determined by the use of a small centrifuge called a hcematocrit, con- 

 structed by BLIX and described and tested by HEDIN. A measured 

 quantity of blood is mixed with a known volume (best an equal volume) 

 of a fluid which prevents coagulation. This mixture is introduced into 

 a tube and then centrifuged. According to HEDIN it is best to treat the 

 blood, which is kept fluid by 1 p. m. oxalate, with an equal volume of 

 a 9 p. m. NaCl solution. After complete centrifugalization, the layer of 

 blood-corpuscles is read off on the graduated tube and the volume of 

 blood-corpuscles (or more correctly the layer of blood-corpuscles) in 100 

 vols. of the blood calculated therefrom. By means of comparative counts, 

 HEDIN and DALAND have found that an approximately constant relation 

 exists between the volume of the layer of blood-corpuscles and the number 

 of red corpuscles under physiological conditions, so that the number of 

 corpuscles may be calculated from the volume. DALAND 3 has shown 

 that such a calculation gives approximate results also in disease, when 

 the size of the blood-corpuscles does not essentially deviate from the 

 normal. In certain diseases, such as pernicious ansemia, this method 

 gives such inaccurate results that it cannot be used. 



KOPPE 4 has shown that in centrifuging blood very rapidly, more 

 than 5000 times per minute, the blood-corpuscles may be so completely 

 separated that all intermediate fluid is removed. Because of the absence 

 of this intermediate fluid the refraction is changed; the outer layers of 

 the erythrocytes containing fat become transparent, and the column 

 of blood-corpuscles becomes transparent and laky. If the volume of 

 the separated column of blood-corpuscles is determined and the number 

 of red blood-corpuscles counted, the absolute volume of these latter 

 can be determined by this method. 



In determining the relation between the weight of blood-corpuscles and 

 the weight of blood-fluid, we generally proceed in the following manner: 



If any substance is found in the blood which belongs exclusively to 

 the plasma and does not occur in the blood-corpuscles, then the amount of 

 plasma contained in the blood may be calculated if we determine the 

 amount of this substance in 100 parts of the plasma or serum respectively 

 on the one side, and in 100 parts of the blood on the other. If we repre- 

 sent the amount of this substance in the plasma by p and that in the 

 blood by 6, then the amount of x in the plasma from 100 parts of blood is 



100.6 



is x = . 



P 



1 Biernacki, Zeitschr. f. physiol. Chem., 19; Eykman, Pfluger's Arch., 60; Hedin, 

 ibid., and Skand. Arch. f. Physiol., 5. 



2 Bugarsky and Tangl, Centralbl. f. Physiol., 11; Stewart, Jouni. of Physiol., 24. 



3 Hedin, Skand. Arch. f. Physiol., 2, 134 and 361, and 5; Pfluger's Arch., 60; Daland, 

 Fortschritte d. Med., 9. 



4 Pfluger's Arch., 10". 



