CARBOHYDRATE METABOLISM 



[PT. Ill 



Fig. 273. 



in 100 gm. of wet egg-white remains constant throughout develop- 

 ment at about i gm. As far as these figures go, then, they confirm 

 the observations of Bywaters, and indicate that there is no preferential 

 absorption of ovomucoid from 

 the white; although there may 

 be from the yolk. This latter 

 possibility is made likely by the 

 fact that the hump on the ovo- 

 mucoid-glucose curve comes 

 just between the two times at 1 1° 

 which the mucoprotein-glucose 

 inside the embryo is high. 



For the percentage of glucose 

 in the ovomucoid molecule, the 

 average value was 11-5, as has 

 already been mentioned. This is probably more accurate than any 

 other estimate, for it was obtained by the Hagedorn-Jensen method 

 after phosphotungstic precipitation. But the curious thing about it 

 is that, when the figures are plotted on a graph, as in Fig. 274, an 

 upward trend is seen. No explanation has been found for this pheno- 

 menon. It is at any rate clear 

 that there is no marked increase 

 in the glucose content of ovo- 

 mucoid at the period when it 

 would be expected in the former 

 of the two views outlined above. 



Continuing the subject of ovo- 

 mucoid-glucose, we may return 

 to the discovery by Miiller & 

 Masayama in 1 899 of an active 

 starch-hy drolysing enzyme in the 

 yolk of unincubated hen's eggs. This amylase would convert "under 

 favourable conditions" 45 per cent, of a 3 per cent, starch solution 

 into the soluble forms of dextrin and isomaltose in 24 hours at 37°. 

 This put on a sure basis the earlier and rather doubtful results of 

 Krukenberg, and was in turn confirmed by Diamare; Herlitzka; 

 and Roger. Idzumi brought forward data which showed that the 

 activity of the extra-embryonic amylase markedly increased as de- 

 velopment proceeded, especially after the 15th day (rising from 40 



>< 7 



6 



5 



Days 



5 6 7 8 9 



10 11 12 13 



Fig. 274. 



4 15 16 17 1819 20 



