942 



ADVENTURES IN RADIOISOTOPE RESEARCH 



rated wholly or principally in the upper molecular layers of the apatite- 

 like crystals which form the mineral constituents of the skeleton. We 

 can determine the extent of renewal of the bone mineral phosphorus by 

 comparing the ^^p content, i. e. the radioactivity of mgm bone mineral 

 P, with the radioactivity of 1 mgm free plasma P. Were the bone phos- 

 phorus entirely renewed in the course of the experiment, the ^^P would 

 be distributed equally between the free P atoms of the apatite-like 

 bone crystallites and the free P atoms of the plasma, the latter being 

 the direct or indirect source of the bone phosphorus. If only 1 per cent 

 of the bone apatite P were renewed in the course of the experiment. 



Table 4. — Percentage Total ^^p Found in some Organs of Rats 



3 - 



u 



min. 



Fig. 3. Change in the specific activity of the plasma inorganic 

 P after subcutaneous injection of labelled phosphate into a rabbit 



