QUANTITATIVE COMPOSITION OF THE BLOOD. 327 



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 1 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 anaemia, this method 

 gives such inaccurate results that it cannot be used. 



KOPPE 2 has shown that in centrifuging blood very rapidly, more 

 than 5000 turnes 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 b, then the amount of x in the plasma from 100 parts of blood is 



100.6 



x= . 



P 



Such a substance, which occurs only in the plasma, is fibrin according 

 to HOPPE-SEYLER, sodium according to BUNGE (in certain kinds of blood) . 

 The experimenters just named have tried to determine the amount of the 

 plasma and blood-corpuscles, respectively, in different kinds of blood, 

 starting from the above-mentioned substances. 



Another method suggested by HOPPE-SEYLER is to determine the 

 total amount of haemoglobin and proteins in a portion of blood, and on 

 the other hand the amount of hemoglobin and proteins in the blood- 

 corpuscles (from an equal portion of the same blood) which have been 

 sufficiently washed with common-salt solution by centrifugal force. The 

 figure obtained, as a difference between these two determinations, corre- 

 sponds to the amount of proteins which was contained in the serum of 



1 Hedin, Skand. Arch. f. Physiol., 2, 134 and 361, and 5; Pfliiger's Arch., 60; 

 Daland, Fortschritte, d. Med., 9. 



2 Pfluger's Arch., 107. 



