ORIGIX OF THE PHOSPHORI'S COMPOUNDS IN E.MBKYO OF CHICKEN 



297 



the percentage of the injected activity present in the fraction and the 

 relative specific activity are recorded; the specific activity of the P 

 extracted from the white of the egg is taken as 100. 



The specific activities obtained when the eggs were incubated for 

 16 and 6 days respectively are seen in Tables 4 and 5. 



Table 4. — Specific Activity of P Extracted Fractions 



OF an Egg Incubated for 16 Days. (The Specific 

 Activity op P Extracted from the White Taken as 100) 



Fraction 



Specific activity 



Embryo: Average acid-soluble P 



Inorganic (without skeleton) P 



Tibia and femur-P 



Creatine-P 



Hexosemonophosphate-P 



Phosphatide-P 



Residual („nucleoprotein") P . . 

 Yolk: Acid-soluble P 



Phosphatide-P 



Residual P 



14 



14 



15 



14 



19 



12 



16 



12 

 0.14 

 1.22 



Table 5. — Specific Activity of P Extracted from 

 Different Fractions of 10 Eggs Incubated for 6 

 Days. (Specific Activity of Embryo Phosphatide P 



Taken as 100) 



Fraction 



Specific activity 



Yolk: 



Embryo: Phosphatide P 



Average (phosphatide) P 



Inorganic P 



Acid-soluble minus inorganic P 



Phosphatide P 



Residual P 



100 



113 



60 



34 



0.032 



1.3 



As the figures show, the phosphatides extracted from the yolk are 

 only slightly active, while those extracted from the embryo show strong 

 activity 1 mgm of embryo phosphatide-P is at least 100 times as active as 

 1 mgm yolk phosphatide P. Furthermore, the specific activity of the 

 embryo phosphatide-P is about as high as that of the embryo inorganic 

 P, showing that an inorganic P atom reaching the embryo has about 

 the same chance of entering the skeleton as of being incorporated in 

 a phosphatide molecule by an enzymic process— which of the two 

 systems it enters is governed solely by probability considerations. 

 From this it follows that the phosphatide molecules in the embryo are 



