SECT. 9] 



PROTEIN METABOLISM 



1069 



that the non-protein nitrogen increases per cent, wet weight in the 

 white, but for the yolk Tomita's rising curve stands in contrast with 

 Aggazzotti's falling one. A private communication from Wright states 

 that recently results have been obtained confirming Aggazzotti on 

 this point (see Fig. 301). Free amino-acids have been found by Fiske 

 & Boyden in the allantoic liquid of the chick, to the extent of 13 mgm. 

 per cent, on the 5th and 7 mgm. per cent, on the loth day of incuba- 

 tion. This is lower than the amino nitrogen of the embryonic blood 

 which Vladimirov & Schmidtt found to vary somewhat erratically 

 between the 13th day and hatching around an average of 54-2 mgm. 



AggazzoCti 



Days -»■ 5 



Fig. 304. 



per cent. After hatching it has an average value of 52-7 mgm. per 

 cent. Such high values are due to the nucleated erythrocytes. 



Certain Japanese workers filled an obvious gap in the data which 

 have so far been reviewed by estimating the total nitrogen of the 

 entire egg throughout, and the whole of the free or combined amino- 

 acid nitrogen. The figures of Sakuragi and of Idzumi are shown 

 in Table 135. As Liebermann had originally thought probable, 

 and as Tangl & von Mituch had later made very likely, there is 

 no change at all in the total nitrogen of the whole egg. Not 

 more than an infinitesimal quantity of this element can escape, in 

 agreement with Krogh's findings discussed in the Section on respira- 

 tion. Sakuragi, as the table shows, estimated the nitrogen in the 

 proteins coagulable with acetic acid, on the one hand, and the 



