ORIGIN OF THE PHOSPHORUS COMPOUNDS IX EMBRVO OF CHICKEN 



299 



equilibrium is reached, the activity should be proportional to the amount 

 of inorganic phosphate present in the phase in question, since the inor- 

 ganic P, among all the P compounds present in the yolk and white, 

 is practically the only source of activity; in the 6 days experiment, for 



Table 6. — Distribution of Injected 



Active Phosphate between 



Different Parts of the Egg 



example, 10% of the 10.3% activity found in the yolk was present as 

 inorganic P. Finally we have to envisage the possibility that a part of 

 the inorganic phosphate injected is not freely movable in the white — it 

 might be precipitated as calcium phosphate or attached to proteins, 

 its mobility being lowered thereby. 



We have also carried out experiments in which 0.1 ml. physiological 

 NaCl solution containing a negligible amount of labelled sodium 

 phosphate was injected into eggs which were not incubated. After the 

 lapse of 5 days the distribution of the activity in different parts of the 

 egg was determined; 97% was found in the white and 3% in the yolk. 

 As was of course to be expected, a still greater preference for the white 

 was shown by the active phosphorus in this experiment; the duration 

 of the experiment was shorter than that of those discussed above, and 

 transport of phosphorus from the white to the embryo was 

 absent. 



To test whether the water injected encountered any hindrance in its 

 propagation through the egg, we injected 0.2 ml. heavy water into the 

 white of the egg; after the lapse of 5 days water was distilled separa- 

 tely from the white and from the yolk and the densities determined. 

 We are much indebted to Mr O. Jacobson for carrying out the density 

 determinations using Linderstrom— Lang's float method. He found 

 that the water prepared from the white had a density exceeding that 

 of normal water by 484 parts per million, while the corresponding figure 

 for the water obtained from the yolk was 437. The deuterium content of 

 the water distilled off from yolk was found to be only about 10% lower 



