290 ADVENTURES IN RADIOISOTOPE RESEARCH 



that of the plasma inorganic P, while the specific activity of the plasma 

 pliosphatide P was appreciably smaller, amounting to only 43%; that 

 of the ovary was very much smaller, namely 3.9%, and about as large 

 as that of the strongest yolk phosphatide P. In the 28 hours experiment 

 as to be expected, the difference in the specific activities was much 

 smaller, the specific activity of the liver phosphatides being only some- 

 w^hat higher than that of the plasma phosphatides. In the 28 hours 

 experiment on the hen which used to lay one egg every other day the 

 amount of phosphatides passing through the plasma on the way into 

 the ovary was, in the course of the experiment, about twice the amount 

 of phosphatides present in the plasma. In the 5 hours experiment, in 

 which the hen experimented on was laying one egg daily, the amount, 

 of phosphatide passing the plasma on the way into the ovary was about 

 half the amount present in the plasma. From the low specific activity 

 of the phosphatide P, that is from the low percentage of newly formed 

 phosphatide in the ovary, it follows that in this organ only an insigni- 

 ficant amount of phosphatide can be formed. We have also to consider 

 that a part of the labelled phosphatides found in the ovary is due to the 

 presence of blood containing the latter. The specific activity of the 

 plasma phosphatide P being appreciably smaller than that of the liver 

 the labelled phosphatides must have come from the liver into the blood 

 and not vice versa. By carrying out experiments in vitro with blood 

 containing labelled sodium phosphate we found only a slight formation 

 of labelled phosphatides, which is in accordance with the above con- 

 clusion. 



The formation of phosphatides in the intestinal mucose by using 

 radioactive phosphorus as indicator was first shown l)y Aetom, Perrier, 

 Santagello, Sarzana and Segre*^). They found in an experiment, 

 carried out on a rat, that after injecting labelled sodium phosphate 

 the phosphatides extracted from the gut after a few days showed a 

 specific activity only exceeded by that of the liver phosphatide P, the 

 ratio of the specific activities being 1.2. The phosphatide production in a 

 laying hen is larger than in any other animal of similar size, as the amount 

 produced daily to be incorporated in the yolk is as much as about 2 

 times that present in the liver which contains more phosphatide than 

 any other organ. The laying hen is, therefore, a very suitable animal 

 for studying phosphatide formation. In our 5 hours experiment the 

 specific activity of the intestinal phosphatide P is much smaller than 

 that of the liver phosphatide P and also than the plasma phosphatide 

 P. The bulk of the labelled P present in the plasma can, therefore, not 

 originate from the intestinal phosphatide and the latter can not be the 

 chief source of the yolk phosphatide. The phosphatides formed in the 



(i^iYaiure 139, 836(1937). 



