Originally published in Biochcm. J. 32, 2147 (1938) 



32. THE ORIGIN OF THE PHOSPHORUS COMPOUNDS 

 IN THE EMBRYO OF THE CHICKEN 



G. C. Hevesy, H. B. Levi and 0. H. Rebbe 



From the Institute of Theoretical Physics, University of Copenhagen 



Several of the numerous compounds containing phosphorus present 

 HI the embryo of the chicken^ occur in the yolk and the white of the 

 egg. Those which do are chiefly phosphatides and nucleoproteins but, 

 as Table 1 shows, other phosphorus compounds also occur in those 

 parts of the egg. 



Table 1. — [Plimmer -;^ Scott, 1909]. Percentage 



OF THE Total, P (94 mgm) at the Beginning and 



the End of Incubation of a Hen's Egg 



KuGLEE [1936] has lately found that, on the twentieth day of incu- 

 bation, i. e. the last day but one, only 25 mgm of the 65 mgm of lipoid 

 P originally present in the yolk remained there; 8 mgm were found in Ihe 

 embryo, and the remainder had been hydrolysed yielding inorganic P. 

 About two-thirds of the phosphatides present were found to be lecilliin 

 and one-third kephalin. In view of the large store of phosphatides present 

 in the yolk even shortly before the egg is hatched, we should expect 

 the embryo to avail itself of this store when it n(MHls phosphatides to 

 build up its nervous system and other organs containing these substan- 

 ces. We can test this point by introducing labellcMl (radioactive) sodium 

 phosphate into the egg before incubation and investigating if and to 

 what extent the phosphatide of th(> yolk and of the (Mubrvo become 



1 A detailed investigation of the soluble pho.sphorus compounds piesenl in Ihe- 

 embryo of the chicken was lerenlly jiublislicd by Xeedham ct nl. (1937). 



