492 ADVENTURES IN RADIOISOTOPE RESEARCH 



The rate of increase of the specific activity of the total acid soluble phosphorus 

 (Sc) present in the corpuscles with time (t) is proportional to the difference in 

 the specific activity of the inorganic P of the plasma (Sp) and that of the corpuscles 



(Si). 



dso 

 = a (Sp — Si). 



dt 



The proportionality factor of the above equation («), denoted as coefficient of 

 penetration, was calculated; the latter was found to be about the same in experi- 

 ments in vitro and in vivo. 



By making use of labelled sodium hexosenionophosphate it was found that, 

 when shaking the latter with rabbit blood, 1/5 hydrolyses within 21/, hours. 

 From sodium hexosemonophosphate administeied, by intravenous injection, to 

 a rabbit after the lapse of l^'o hours less than ^I-^q% was left in the circulation. 



By comparing the rate of formation of labelled ester P in the corpuscles after 

 introducing in one case labelled hexosemonophosphate in the other labelled inor- 

 ganic phosphate, we arrive at the result that the labelled phosphate ions which 

 penetrate into the corpuscles are utilised for the formation of labelled ester molecvi- 

 les. If any labelled hexosemonophosphate penetrates into the corpuscle at all, 

 the rate of its penetration is much lower than that of tbe phosphate ions. 



The rate of renewal of the phosphatide molecules present in the blood was 

 found to be very much slower than that of the acid-soluble compounds. The 

 synthesis of the former was found to take place in the organs from which they 

 are carried into the circulation. The replacement of the corpuscle phosphatides 

 is a mvich slower process than that of the phosphatides present in the plasma, 

 the ratio in human blood after one day being (5:1, after a week 2:1. 



