OMGIX OF THE PHOSPHORUS COMPOUNDS IX EMBRYO OF CHICKEN 295 



The yolk was dried with acetone and the phosphatides extracted three 

 times from the dry product with a 3:1 alcohol-ether mixture. The 

 alcohol and other were then evaporated off at about 50° hi vacuo and 

 the residue was taken up with light petroleum and lil1(>ro(l. The filtrate 

 was evaporated //? vacuo, the residue ignited, and the phosphorus 

 precipitated as ammonium magnesium phosphate. 



Another part of the yolk was treated as follows. The acid-soluble 

 compounds were extracted, then the phosphatides were removed as 

 described above, and the residual part containing mainly vitelUn-P 

 and nucleoprotein-P was ignited; the P content of this last part was 

 determined as ammonium magnesium phosphate. 



The embryos were dropped, immediately after being removed from 

 their eggs, into liquid air and were subsequently pulverized. The embryo 

 powder was then extracted several times with cold trichloracetic acid— 

 in the first two extractions a 10% solution was used, and later one oif 

 5%. The extract was filtered into cold concentrated NaOH solution 

 and divided into three parts, (a), (6) and (c). From {a) a sample of the 

 average acid-soluble P of the embryo was secured, {b) was precipitated 

 with 25% barium acetate solution at pR 6.5. The cold precipitate was 

 washed with a dilute barium acetate solution, centrifuged and dissolved 

 in a few drops of cold HNO3. The inorganic P present was then precipi- 

 tated by adding Fiske's reagent. The remaining filtrate was hydrolysed 

 with N HCl at 100° for 7 min. to split the two labile phosphate radicals 

 of adenosinetriphosphoric acid. The phosphorus set free was finally 

 precipitated as ammonium magnesium phosphate, Barium hydroxide 

 was added to the filtrate from the barium precipitation to remove any 

 inorganic P, the precipitate was separated by centrifuging and ethyl 

 alcohol was added to the remaining liquid until an alcohol concentration 

 of nearly 60% was reached. The precipitate obtained after addition 

 of alcohol [OsTERN et al., 1936] contained the hexosemonophosphate. 

 Its P content was determined in the usual way. The third part, (c), 

 was hydrolysed with N HCl in the presence of 0.1 M ammonium 

 molybdate for 30 min. at 40°. In the course of 30 min. most of the 

 phosphagen present decomposed, so that the inorganic P originally pres- 

 ent as such, and that obtained by the decomposition of the phosphagen^, 

 were secured together in this fraction. 



After removal of the acid-soluble P the embryo was thoroughly treated 

 with an alcohol-ether mixture, as described above, to remove the phos- 

 phatides. The residue, containing mainly nucleoprotein-P, was ignited 

 with concentrated sulphuric and nitric acids and the P precipitated in 

 the usual way. 



(i^On the phosphagen content of the embryo of the chicken, cf. Lehmann 

 and Needham [1937]. 



