ADVENTURES IN RADIOISOTOPE RESEARCH 



521 



Table 1. — Disappeakance of Labelled Acid- 

 soluble P Compounds from the Cokpuscles 



Time elapsed after injecting 



the blood of rabbit B into 



rabbit A 



Per cent of labelled acid-soluble 



P injected, present in 1 cc. 



corpuscle of rabbit A 



2.5 min 



5 „ 



6.5 ,, 



8.5 „ 



26.5 „ 



60 „ 



120 „ 



210 „ 



3.39 

 3.21 

 3.39 

 3.30 

 3.12 

 2.88 

 2.58 

 1.35 



100 



.2x> 



a. 



a> 



o 

 a. 



_3 

 o 



s 



mm. 



Fig. 1 . Disappearance of labelled acid-soluble P from corpuscles, injected 

 into the circulation of a rabbit. 



DISCUSSION 



The sole difference between the normal and the labelled corpuscles is 

 that in some of the molecules present in the normal ones P (having the 

 mass number 31) is replaced by radioactive P (having the mass number 

 32). In 1 cc. corpuscles of rabbit B, 0.06 mgm phosphatide P was present. 

 Of these 0.06 mgm, lO^^^ mgm were radioactive ^^P atoms. As 1 cc. contains 

 about 3 • 10^ corpuscles, one corpuscle contains on an average 10^^^ mgm 

 32p or only about one corpuscle in a hundred contained an active phos- 

 phatide molecule. After injecting the blood sample of rabbit B into rabbit 

 A, a strong dilution of the labelled phosphatides took place: only one 

 in about three thousand corpuscles now contains a radioactive phospha- 

 tide P atom. The replacement of a minute percentage of the ^ip atoms 

 by 32p atoms in the P compounds of the corpuscles can hardly influence 

 to any noticeable extent the chemical properties of the corpuscles and 



