CHANGES IN COMPOSITION DURING GROWTH. 13 



proportional to the increase in water." This is shown by the fact that 

 the percentage of solids did not greatly change from the time of the 

 June drop to the period at which the peaches were considered market 

 ripe. On the other hand, during the same period the stone changed 

 greatly in its nature. As it became harder and more mature the per- 

 centage of water materially decreased and the percentage of solids 

 increased from 9.37 at the period of the June drop to 66. 94 when the 

 peaches were market ripe. The solid content of the kernel increased 

 from 6.89 per cent at the time of the June drop to 44.78 per cent when 

 the peaches were market ripe. At the same time it should be noted 

 that the percentage of solids in the kernel did not materially increase 

 until after the hardening of the stone. 



The percentage of marc remained fairly constant, showing, how- 

 ever, a slight increase somewhat commensurate with that of the 

 increase in solids until the hardening of the stone. After that, how- 

 ever, the percentage of marc greatly decreased, until at the time of 

 market ripeness it was about one-third as great as at the earlier stages 

 in the life history of the peach. The term "marc" is here used in 

 its usual significance to apply to the total insoluble matter of the flesh 

 of the peach, including the skin. It was determined by a thorough 

 exhaustion with water by the method described in the previous work 

 with apples. 6 



The percentage of reducing sugars varied less than was the case 

 with the other substances just considered. A distinct tendency to 

 decrease, however, is evident. This decrease is also true of the per- 

 centage of nitrogenous substances in all their forms calculated as total 

 protein, albuminoids and amido bodies, and also of ash. On the other 

 hand, the percentage of sucrose and of acids increased from the begin- 

 ning to the end of the experiment. 



The average composition at market ripeness of seven varieties of 

 peaches, six of which are included in Table II, is as follows: 



Composition of whole peach. 



Grams. 



Weight ( per peach) 71. 66 



Per cent. 



Flesh 92.31 



Stone - 7.02 



Kernel 69 



Solids in flesh c 14. 45 



Solids in stone d 67. 22 



Solids in embryo c 47. 50 



Also true in the case of apples. U. S. Dept. Agr., Bureau of Chemistry Bui. 94, 

 Studies on Apples. 

 & Loc. cit. 



c Dried in vacuo at 70 C. 

 rf Dried at 100 C. 



