DETERMINATION OF RED CORPUSCLE CONTENT 



529 



interchanges with the erythrocytes of the circulating blood and, corres- 

 pondingly, to what extent it participates in the dilution of the labelled 

 corpuscles. Since our experiments were carried out with narcoticized 

 rabbits and, as shown by Barcroft (1934), in ether narcosis the blood 

 reserves of the body are to a very large extent released, our results are 

 independent of the above mentioned source of error and indicate the 

 total erythrocyte content of the rabbits investigated. 



Table 4 



Rabbit 



Weight 

 in gm 



Weight of 



corpuscles 



injected 



Activity 



per gm 



corpuscles 



injected 



Activity 



per gm 



corpuscle 



sample*!' 



Total cor- 

 puscle con- 

 tent 

 in gm 



Corpuscle 



content in 



gm per kgm 



rabbit 



weight 



B. 2 . 



B. 3 . 



B. 6 . 



B. 7 . 



B. 8 . 



B. 9 . 



B. 10 . 



B. 11(2) 



20.7 

 20.5 

 23.3 

 20.6 

 25.9 

 20.8 

 20.7 

 14.5 



^1^ Average of samples secured between 3 and 9 min (comp. Table 1). 

 ^2) Anemia following previous operation. Hematocrit value — 22.5. 



Radio-Phosphorus and Radio-Iron as Indicators 



Hahn, Balfour et al. (1941) determined the corpuscle volume of 

 the dog, using radio-iron as an indicator. Within a few days after admi- 

 nistration of radio-iron to dogs, most of the radio-iron present in the 

 body is concentrated in the erythrocytes as a constituent of the hemo- 

 globin molecules. Such erythrocytes labelled by the presence of radio- 

 iron were used in the same way to determine the red corpuscle volume 

 of the dogs as corpuscles labelled by the presence of radiophosphorus 

 were applied by Hahn and Hevesy (1940) and by the present writers 

 to determine the red corpuscle volume of the rabbit. In the determin- 

 ation of the red corpuscle volume, the radio-phosphorus method has the 

 following advantages. Blood samples can be activated in vitro, while 

 such a procedure cannot be carried out when using radio-iron. Corpus- 

 cles containing labelled haemoglobin can only be obtained in experi- 

 ments in vivo. Furthermore, radio-phosphorus is very much easier to 

 procure than radio-iron, since the preparation of radio-iron in sufficient 

 quantities requires powerful tools in contrast to the preparation of 

 radio-phosphorus. 



34 Hevesy 



