Originally published in Kgl. Danske Videnskabenies Sel-skub- Biologinke Meddel- 



elser. 14, 2 (1938) 



31. ORIGIN OF PHOSPHORUS COMPOUNDS IN HENS' EGGS 



G. Hevesy and L. Hahn 



From tlio Institute of Theoretical Physics, University of (Copenhagen 



In this paper we discuss the origin of eggs phospliorus by making use 

 of labelled (radioactive) phosphate as indicator. As the presence of 

 labelled phosphorus in organic compounds proves that these compounds 

 were synthetised since the administration of the labelled inorganic 

 phosphate we can draw conclusions as to the place and time of for- 

 mation of the lecithin and other compounds containing phosphorus 

 and present in the egg, by making use of the above mentioned metluxf 

 In the hope of finding which phosphorus compounds of the blood ar(> 

 responsible for the formation of the lecithin and possibly other phospho- 

 rus compounds of the egg we administered labelled sodium phosphate 

 to hens by subcutaneous injection and investigated after some time the 

 yolks removed from the ovary and further the composition of blood 

 and of some of the organs. In other experiments eggs, laid at 

 different times, were investigated. Finally we carried out also a few 

 experiments in vitro. 



Several of the compounds building up the egg contain phosphorus. 

 Lecithin and other phosphatides form about one tenth of the yolk of 

 the hens egg, the ratio of P to that of the other elements present in these 

 compounds being about 1 : 25. From the phosphoprotein of the yolk 

 vitellin is the most abundant, it contains on the average 0.54% P. 

 The total of phosphoprotein P present in the yolk is somewhat less 

 than half of the phosphatide P present, while only small amounts of 

 nucleoprotein P are found, as seen in Table l<i). 



The phosphatide P content of the average yolk amounts to 60 mgm 

 and its total P content to about 94 mgm. The total P content of tlu^ 

 yolk is thus about 0.6% of its total fresh weight, while that of the white 

 of the egg is much smaller, amounting to about 0.01%. The P content 

 per gm of the small yolks found in the ovary is appreciably lower as 

 seen from Table 2 and increases with the increasing size of the yolk. 



(1' R. II. A. I'LiMMEii and F. M. ScoiT, Physiol. 38, 247. (1909.) 



IS Hevesv 



