520 BLOOD VOLUME DETERMINATION 



DETERMINATION OF THE BLOOD VOLUME OF A CHICK WEIGHING 



135 gm 



Labelled sodium phosphate was administered to chick B and, 24 hours 

 later, 0.5 cc. blood of this chick was injected into the jugular vein of 

 chick A. The haematocrit values were found to be 0.26 and 0.28, respec- 

 tively. We found the activity of the phosphatides extracted from the 

 corpuscles of 1 cc. blood of chick A to be 7.6, taking that of the phospha- 

 tides secured from the corpuscles of 1 cc. blood of chick B to be 100. 

 The total blood volume of chick A is thus 



X= 15^^!^ -0.5 = 6.1, 

 7.6-1 



or 45 cc. per kgm weight. 



LOSS OF LABELLED P COMPOUNDS BY THE CORPUSCLES 



We wish now to discuss the possible loss of labelled P compounds by 

 the corpuscles during the interval between the injection of labelled 

 corpuscles of rabbit B into the circulation of rabbit A and the securing 

 of blood samples of rabbit A. Such a loss would clearly involve a source 

 of error by leading to too high values for the blood volume to be deter- 

 mined. As to the loss of labelled phosphatides, we found that the labelled 

 phosphatide content of the corpuscles of rabbit A, after the lapse of 

 1 hour, amounts to 90 per cent of that found after the lapse of 6 min. 

 This result shows that the disappearance of labelled phosphatides from 

 the corpuscles takes place at a slow rate. 



As to the disappearance of the labelled acid-soluble P molecules from 

 the corpuscles, we find the following result. The labelled acid-soluble 

 P content of 1 cc. corpuscle of rabbit A, 8.5 min after injecting the 

 blood of rabbit B into rabbit A, is, as seen in Table 1 and Fig. 1, within 

 the errors of experiment, identical with that found after 2.5 min. 



We have now to investigate if, during the lapse of 5 min or more, 

 after which time blood samples in the experiments described in this 

 paper were secured, a uniform mixing of the labelled corpuscles of rabbit 

 B in the circulation of rabbit A took place. From the data contained in 

 Table 1 and Fig. 1 we can conclude that, already after the lapse of 

 2.5 min., a uniform mixing actually took place. Such a result in the 

 case of a small animal with fast circulation could be expected since, 

 in experiments carried out on human subjects, a uniform mixing of 

 dyestuffs injected into the plasma was found to take place in the course 

 of 6 min. (Rowntree et alia, 1929; Graff et alia, 1931). 



