MANUFACTURE AND UTILIZATION OF CARBOHYDRATES 179 



acidity in apple spurs is shown in Figs. 20 and 21, In the spring, starch 

 and sugar decreased rapidly in these spurs and acidity rose. This may be 

 interpreted as indicating the hydrolysis of starch to sugar and the incom- 



Fig. 20.- — Starch, reducing sugar content and titratable acidity of bearing apple spurs 

 compared. (After Hooker .''^'>°) 



plete oxidation of the sugar to acid. Some of the decrease in sugar is 

 explained by removal to the developing leaves and flowers. The increase 

 in acidity in the spring lasted longer and reached a higher maximum in 



Fig. 21.— Starch, reducing sugar content and titratable acidity of non-bearing apple spurs 

 compared. (After Hooker. '^'^°) 



bearing spurs. At the same time the consumption of reducing sugars 

 was more complete. This may be associated with greater respiratory 

 activity in flowers. Respiratory activity is particularly pronounced 

 in floral parts, germinating seeds and growing parts in general. 



