182 



ADVENTURES IX RADIOISOTOPE RESEARCH 



Tablp: 15. 



out in 5 pieces the labelled P content of which is seen below, I denoting 

 the proximal end. 



Table 16. 



Weight of 



the fresh 



tissue in 



mgm 



I 



II 



III 



IV 



V 



Labelled V found 

 in 1 mgm fresh 

 tissue as a per- 

 centage of the 

 amount given 



0.0062 

 0.0027 

 0.00040 











One cc. of blood contained 0.5% of the activity injected; assuming 

 a blood content of 10 cc, only 5% of the labelled phosphorus injected 

 was present in the circulation after the lapse of 1 hour. Only 1 hour after 

 administering the labelled phosphorus the tibia phosphorus was found 

 to be 1000 times less active than the blood phosphorus, while for the 

 molars the corresponding ratio was found to be 5000 and for the incisors 

 (inclusive of growth) 2700. We also determined the activity of the acid 

 soluble phosphorus extracted from the muscles of the rat and found 

 1 mgm to contain 0.042% of the labelled P given. From this figure and 

 those found for the activity of the tooth and tibia phosphorus 1o bo 

 seen in Table 16 it follows that a comparatively fast phosphorus exchange 

 is taking place in the muscle compared with that ascertained in Ihe 

 l)ones and the teeth. 



