ORIGIN OF THE PHOSPHORUS COMPOUNDS IN EMBRYO OF CHICKEN 301 



i'rom the labelled hcxomonophosphate injected and is incorporated in 

 the different phosphorus compounds of the embryo, while the hcxomono- 

 phosphate molecules extracted from the embryo are not those syn- 

 thesized by Dr Ostern but are molecules built up by the chicken's 

 embryo. 



Tablk 7. — Specific Activity of P from Different 



Fractions from Two Eggs Incubated for 14 Days after 



THE Injection of Radioactive HexosemonoPhosphate. 



(Specific Activity' of P Extracted from the White 



Taken as 100) 



Fraction 



Specific activity 



Embryo: Inorganic P 



Hexosemonophosphate-P . . . . 



Phosphatide-P 



Residual ("nucleoprotein") P 

 Yolk: Inorganic P 



Hexosemonophosphate-P . . . . 



Phosphatide -{- residual P . . . 



24 

 26 

 20 

 11 

 36 

 18 

 



The low value found for the residual P of the embryo may possibly 

 1)0 due to the building up of a part of the nucleoprotein fraction at an 

 early date before much of the active hexosemonophosphate introduced 

 has decomposed. The phosphatide-P and residual P extracted from the 

 yolk were found to be inactive. These fractions were found to be only 

 slightly active even after the injection of strongly active inorganic P, 

 and the absence of activity after the injection into the egg of the much 

 weaker hexosemonophosphate was only to be expected. The hexose- 

 monophosphate fraction isolated from the yolk had a specific activity 

 of 18; the inorganic P, 36. The larger value found for the specific activity 

 of the inorganic P is possibly to be explained in the following way. 

 Some active hexosemonophosphate diffuses into the yolk and partly 

 decomposes into active inorganic P: this is the source of most of the 

 active inorganic P which we isolated from the yolk. The hexosemono- 

 phosphate, isolated by the method outlined on p. 296, contains, besides 

 the active hexosemonophosphate, some non-active hexosemonophos- 

 phate and possibly also some other acid-soluble P compound separated 

 simultaneously, which diminished the specific activity of the "hexose 

 monophosphate" fraction isolated from the yolk. In the embryo, on 

 account of the strong enzymic action prevailing there, all phosphorus- 

 compounds become labelled; on the other hand, in the yolk, as we 

 have just mentioned, no such labelling takes place. 



