300 ADVENTURES IN RADIOISOTOPE RESEARCH 



than that of the water from the white, showing that in the course of 

 5 days the water injected w^as very nearly evenly distributed throughout 

 the egg, in contrast to the injected active phosphate. The anomalous 

 behaviour of the latter, while of interest in the study of the circulation 

 of phosphate ions in wdiite and yolk, in no way influences the investigat- 

 ion of the main problem discussed in this paper— namely, if and to 

 what extent the molecules of the different phosphorus compounds 

 present in the embryo are built up there or are drawn, from the yolk. 



Introduction of labelled hexosemonophosphate into the egg to be incubated 



In one set of experiments, instead of following up the fate of labelled 

 inorganic P in incubated eggs, we introduced radioactive hexosemono- 

 phosphate. Prof. Parnas very kindly presented us with this compound 

 (prepared by Dr Ostern) in the form of barium hexosemonophosphate, 

 from which, by treatment with sodium sulphate in the cold, the sodium 

 compoundof the ester was obtained. 0.2 ml., containing about 0.2 mgm 

 P as hexosemonophosphate salt and about 3 mgm. sodium sulphate, was. 

 injected into the white of each of the eggs to be incubated; to avoid 

 decomposition of the ester, the solution was kept ice-cooled until it was 

 injected into the egg. Of the 10 eggs receiving this treatment, only two 

 supplied living embryos. After a lapse of 14 days, 7.7% of the activity 

 injected was found to have been incorporated in the embryo (5.8% in 

 the yolk) and a large fraction was also to be found in the white and in 

 the connecting liquids. If, of the various fractions extracted from the 

 embryo, we had only found activity in the fraction containing hexose- 

 monophosphate, we should have had to conclude that the hexosemono- 

 phosphate does not decompose in the egg but enters the embryo as 

 such. In view of the results obtained in the experiments carried out 

 with labelled inorganic phosphate, however, such behaviour was hardly 

 to be expected. Furthermore, Kay [1926] found that in the embryo 

 tlie phosphatase activity of the developing bone was extremely high, 

 the phosphatase decomposing the hexosemonophosphate. We isolated 

 the hexosemonophosphate from the embryo, as described on p. 295, 

 and compared the specific activity of this fraction with that of the 

 inorganic phosphate ( -}-creatine-P). We also isolated the phosphatide 

 fraction and the residual phosphorus fraction containing mainly nucleo- 

 protein-P. As Table 7 show^s, no conspicuous difference can be seen 

 between the specific activities of the different fractions of the embryo, 

 with the possible exception of the residual P. In these experiments small 

 activities had to be measured and the differences found between the 

 first three fractions lie within the errors of the experiment. The results 

 obtained suggest the explanation that active inorganic P splits off 



