1230 METABOLISM OF LIPOIDS, STEROLS, [pt. m 



Needham applied a new and approximately quantitative estimation 

 method to the egg during its development. The resulting figures 

 (Black Leghorn eggs) are shown in Fig. 395. It will be seen that the 

 total inositol in the egg rises from 7 mgm. per cent, at the beginning 

 to over 60 at the end. The general shape of the curve is doubly 

 peaked, the first occurring about the loth day and the second one 

 being coincident with hatching. Between the two maxima there is a 

 depression in which the total inositol descends to a level not greatly 



60 



50' 



40- 



30 



20 



10 

 t 



InosKol. 



O = ^hite 

 • = yolk 

 n = remainder 

 V = embryo 

 H = Total 



1 1— 1 — 



20 21 



1 1 r 



Days-* 



1 1 r- 



10 



Fig- 395- 



above that which it occupied at the beginning. If all the inositol 

 present at the end of development had been in the form of phytin 

 or some similar compound at the beginning, there would be some 

 62 mgm. per cent, of water-soluble organic phosphorus present at 

 the beginning, while, in point of fact, Plimmer & Scott only found 

 27 mgm. per cent, of water-soluble organic phosphorus present in 

 the fertilised but unincubated egg. So if phytin were the precursor 

 of inositol in the egg, about three times as much water-soluble 

 organic phosphorus as is actually there would be needed to account 

 for it. Of course, the precursor might be a di- or a tri-phosphate of 



