534 ADVENTURES IN RADIOISOTOPE RESEARCH 



bound state. Much of the decay of thorium emanation leads to formation 

 of such thorium B particles. 



That much of the activity of the red corpuscles was due to colloidal 

 or protein bound particles was shown by making use of the fact<^) that 

 on a zinc plate, dipped into a solution containing colloidal ThB (lead 

 isotope) or ThC (wismuth isotope), much more activity accumulates 

 when acidifying the solution. 



WhenO.Sgmof corpuscles were hemolyzed by adding the same volume 

 of water and one half of that volume was shaken after immersion of a 

 zinc plate (2x2 mm) for 5 minutes, the washed zinc plate had an activity 

 of 3540 counts per min. When first adding 0.5 ml of 1 N HCl to the other 

 half of the hemolysate and then repeating the experiment, the zinc 

 plate had an activity about 4 times as large, namely 14,897 counts per 

 min than in the first mentioned experiment. The addition of acid con- 

 verted much of the colloidal and protein bound active deposit into the 

 ionic state. It follows that about 3/4 of the active deposit present in 

 the corpuscles was in a colloidal or protein bound state. 



The reults of blood volume determinations obtained by Nylin and 

 the present writer in a clinical investigation in which thorium B labelled 

 red corpuscles were applied, will be shortly published. 



Summary 



By leading thoron (thoi'ium emanation) through blood for a few minutes, red 

 corpuscles labelled by the presence of the active deposit ot thorium are obtained. 



The red corpuscles of the rabbit conserve their activity for several hours, less 

 than 0.5 per cent being lost when shaking the active erythrocytes with inactive 

 plasma for 2 hr at 37°. 



^i^G. B.EVESY, Sitzungsber. Wiener Akademie der Wiss. 127, Abt 2 a. (1918). 



