RED CORPUSCLE CONTEXT OF THE CIRCULATING BLOOD 



563 



securing of the blood samples. (C) During the last mentioned interval, 

 some radio-phosphorus may leave the corpuscles. 



(^1) Though the amount of plasma adherent to 1 gm corpuscles of llie 

 standard preparation can be assumed to be equal to the amount of 

 plasma adherent to 1 gm corpuscles secured after the injection, the 

 incomplete separation of corpuscles and plasma involves an error which 

 becomes obvious from the following example. 1 gm standard preparation 

 is composed of 0.97 gm corpuscles and 0.03 gm plasma and has an 

 activity = 1000. As the activity of 1 gm corpuscles is about equal to 

 the activity of 1 gm plasma after 2 hours of rotation in the thermostat, 

 970 activity units are due to the corpuscles and 30 to the plasma. In a 

 sample secured 3 minutes after the injection, the activity of 1 gm plasma 

 declines to V^ of its previous value. If, now, the activity of 1 gm of the 

 sample is again assumed to be 1000, the share of the adherent plasma 

 activity is only 8, the corpuscle activity being 992. When comparing 

 the activity of the two corpuscle samples, w^e get thus a value of the 

 corpuscle content of the circulation which is 2.3 per cent too high. The 

 activity of the plasma adherent to the sample secured after the lapse 

 of 10 minutes is still lower than the activity of the plasma secured after 

 3 minutes, f/i. about i/io of ^^^^ activity of the plasma injected. When 

 securing the blood samples after the lapse of 10 minutes, we overestimate 

 the total corpuscle content of the circulation with about 3 per cent. 

 The above result was obtained after centrifuging the blood sample with 

 5000 revolutions per minute for 10 minutes. 



{B) As the injected blood contains active plasma, some radio-phos- 

 phorus will penetrate into the corpuscles during the experiment lasting 

 5 — 10 minutes. Phosphate penetrates at a much higher rate through the 

 capillary wall (Hahn and Hevesy, 1941) than through the membrane 

 of the erythrocytes. The bulk of the radio-phosphorus content of the 

 plasma will, therefore, leave the plasma in the course of 5 minutes, 

 much reducing the amount of radio-phosphorus which otherwise would 

 penetrate into the corpuscles. Table 2 shows the rate of disappearance 

 of radio-phosphorus from the plasma and the percentage of plasma 



Table 2. — Penetration of ^^P from the Plasma into 



THE Corpuscles after Injecting Labelled Plasma 



into the Circulation 



30^ 



