IOI4 CARBOHYDRATE METABOLISM [pt. iii 



Before leaving Fig. 269, attention may be drawn to the figures 

 for inositol-content of the whole egg, as determined by Needham's 

 method. Owing to the inferior accuracy of this method, which yet is 

 the only available one, no stress can be laid on the actual values, but 

 there is a reciprocal correlation between the total cyclose and the total 

 carbohydrate. 



8-4. Carbohydrate and Fat 



So far the analyses which have been described were done in all 

 cases upon the embryo and the yolk and white separately. Sakuragi's 

 important paper of 191 7 was based on analyses of the entire egg at 

 different stages, and it is interesting to see how his results coincide 

 with what has already been said. He adopted the plan of making 

 a number of parallel observations with different methods, so that 

 Fig. 275, which sums them up graphically, involves the following 

 fractions : 



A. (Hydrolysed residue after alcohol extraction) glucose of ovoalbumen, ovomucoid 



and glycogen. 



B. (Alcohol extract after hydrolysis -D.), glucose of glycogen. 



C. (Filtrate from protein coagulated by heat) free glucose. 



D. (Alcohol extract before hydrolysis) free glucose. 



E. (A. +B.+D.) total glucose. 



F. (Hydrolysed residue after water extraction) glucose of proteins and of glycogen? 



G. (Water extract) free glucose + ? 



H. (Hydrolysed water extract with hydrochloric acid) free glucose + ? 



I. (Total hydrolysis of whole egg with hydrochloric acid direct) total glucose. 



J. (Ditto, a second time.) 



K. (F.+H.) total glucose. 



As Fig. 275 shows, Sakuragi did not observe any rise of total glucose 

 in the egg as a whole between the 8th and i ith days. It is interesting 

 that the free glucose determined in several different ways diminishes 

 and then rises ; this agrees with a great deal of earlier and later work. 

 The glycogen, estimated directly, rises all the time. The unknown 

 hydrolysable carbohydrate which is found in the watery extract has 

 the effect of diminishing but not of completely abolishing the fall and 

 subsequent rise of the free glucose. Its presence warns us that there 

 may be many important processes in the carbohydrate changes in the 

 developing hen's egg which are entirely hidden from us at present. 

 The decrease in glucose combined with protein found by Sakuragi 

 equates with the similar decrease in Fig. 269, though the course taken 

 is very different, and Sakuragi himself made no attempt to explain it. 



