164 ADVENTUKES IN KADIOISOTOPE RESEARCH 



actual growth, the latter being much more effective in introducing 

 rad. P into the tissue. An appreciable part of the foetus has actually 

 been built up by utilising the circulating rad. P and has correspond- 

 ingly a high ^^P content. This is still more the case for the rapidly growing 

 placenta. In the case of the second animal, pregnancy occurred at a 

 much later date than the intake of rad. P. The foetus was nourished 

 by blood poor in rad. P, and correspondingly the rad. P content of 

 the ash of the foeta was much less. Whereas in the first case the 

 weight of all foeta was 345 mgm, in the second case it was only 52 

 mgm, the weight of the placenta ash being 43 and 12 mgm res- 

 pectively. 



We also had an opportunity to find what was a comparatively very 

 high rad. P content for the placenta of a human subject; as much as 

 ■0.095 per cent was found in the ash of the placenta, which weighed 

 133.8 mgm. We can estimate the total ash which the patient in question 

 should give on ignition as 2800 gm. The weight of the placenta ash 

 thus amounted to less than V20000 ^^ ^^^^ total ash, while the rad. P con- 

 tent was as much as i/^^j^ of the total amount of rad. P given, showing 

 a concentration of rad. P in the placenta ash more than twenty times as 

 great as that in the average ash of the body. One might try to explain 

 the high rad. P content of the placenta by its high blood content. That 

 this explanation fails is seen, however, from the following. The ash 

 of the placenta was found to weigh 133.8 mgm and the ash of about 

 5 cc. of blood would weigh the same. But as early as 8 hours after the 

 injection of rad. P such a volume of blood was found to contain less 

 than Vioooo ^^ ^^^ latter^ and after the lapse of a few days — when the 

 placenta were removed — still less. The high rad. P content of the pla- 

 centa cannot therefore l)e due to their blood content. No activity could 

 be detected in the ash of the few weeks' old foetus removed in the course 

 of an operation, but the weight of this sample amounted to only a few 

 mgm. 



UPTAKE OF PHOSPHORUS BY RACHITIC RATS 



We carried out a set of experiments on two months' old rachitic rats, 

 which had been used by Frederica and Gudjonson in their experi- 

 ments on the effect of vitamin A and D deficiency on rickets. The rats 

 were fed before and during the experiments on a diet free from or poor 

 in vitamins A and D. The weights of the animals before the experiment 

 were 89, 83, 85, 93, 90, 95 and 103 gm. The results are seen in TabJp 11 



1 In the case of another subject wo found 1 cc. of blood to contain 0.0027 pcM- 

 cent of the phosphorus injected after the lapse of 12 hours, the blood corpusc^les 

 containing 11 times as much active phosphorus as the plasma. 



