SECT. 8] 



CARBOHYDRATE METABOLISM 



1053 



Tomiba 

 Effect of autolysis on egg lactic acid 



Yolk 



Tomita's injection experiments were continued by Matsumoto 

 several years later, who confirmed some of his normal figures and 

 found that injected glycerol had not the least effect on the magnitude 

 of the lactic acid content in either yolk or white. Tomita himself 

 also studied the effect of autolysis on the lactic acid of the egg. As 

 the diagram in Fig. 294 shows, no increase in the lactic acid of the 

 white was to be seen even after 14 days' autolysis. The addition of 

 glucose or alanine to this had no effect whatever, and no extra lactic 

 acid was formed. The yolk, on the other hand, showed a marked 

 rise in lactic acid when auto- 

 lysed.^ As the second experi- 

 ment demonstrates, it rose for 

 about a week, but later it was 

 found to fall, the lactic acid 

 itself being destroyed. Ad- 

 dition of glucose to the yolk 

 autolysate at the beginning of 

 the experiment led to enormous 

 rises in the lactic acid formed, 

 e.g. from 30 to 300 or 400 mgm., 

 while alanine gave no such in- 

 crease, whatever its concentra- 

 tion. Tomita concluded from this that the enzyme which hydrolyses 

 the free glucose into the lactic acid existed exclusively in the yolk. 

 For the closely related work of Stepanek, see Section 14-6. 



Tomita drew attention to the fact that the maximum figure for 

 lactic acid obtained in normal autolysis was quite similar to the 

 maximum observed during normal development. 



Ido's experiments were planned rather differently. Taking hen's 

 eggs after variable periods of normal development, he vaselined them 

 so as to exclude air and returned them to the incubator for several 

 weeks. Considerable amounts of lactic acid accumulated, but the 

 correlation between lactic acid formed and glucose destroyed was 

 only precise in the case of embryos at least as old as 5 days. In un- 

 incubated eggs thus treated only 2 7 per cent, of the glucose disappearing 

 could be accounted for by the lactic acid formed. These experiments 

 are of interest in connection with Byerly's findings (see p. 607). 



The hen's egg is not the only type which has been examined with 



^ Confirmed subsequently by Needham & Stephenson. 



Fig. 294. 



