176 FUNDAMENTALS OF FRUIT PRODUCTION 



Table 65. — Reducing Sugar Content of Devei.oping Apples and Pears"' 



cate that the carbohydrate stores in the roots do not return to the tops. 

 They are used by the roots. Cambial activity depends on the carbo- 

 hydrate stored in the medullary rays and the starch sheath. Bud 

 development in the spring depends largely on the carbohydrate stored 

 in the pith or leaf gap near the bud. 



CARBOHYDRATE UTILIZATION 



Carbohydrates are used in any one of the following ways: 



1. For tissue building, that is for the construction of other carbo- 

 hydrates, or of different substances manufactured from carbohydrates, 

 which enter into the composition of plant cells. 



2. For the retention of moisture. 



3. To increase osmotic concentration. 



4. As a source of energy. 



In Tissue Building. — According to Czapek, glucose is a constituent 

 of every living cell and therefore may be considered a necessary part 

 of the chemical equipment of living matter. The great value of glucose 

 in metabolism is probably associated with the ease with which it is altered 

 to a number of different but related compounds. Through its enolitic 

 form it may be changed to fructose and mannose. Glucose, fructose 

 and mannose exist in at least five forms each. Wherever glucose is 

 present in solution, as in protoplasm, certain of these forms — depending 



