12 POMOLOGY 



percentage of malic acid decreased from the first examination 

 to the full maturity of the fruit. The percentage of total 

 sugar estimated as invert sugar increased steadily from the 

 first examination to full maturity. It is notable that after 

 the maximum content of starch is reached, the percentage of 

 starch and invert sugar taken together remains approxi- 

 mately constant. 



More recently Thatcher^ has shown that the only enzymes 

 which were found to participate in the changes in the carbo- 

 hydrates of apples during the ripening process were the 

 oxidases. 



11. Composition of apples in common storage. — It is of 

 interest to follow the ripening process as it occurs after the 

 fruit is picked and placed in storage. The work of Bigelow 

 et al.," Browne^ and Kulisch,'* are in substantial agreement, 

 although performed under widely differing conditions. 



Bigelow's work with Rhode Island Greening apple illus- 

 trates this ripening process, the apples having been picked 

 between October 6 and November 7. The curves in Fig. 2 

 show graphically the progress of the ripening. By referring 

 to them it will be noted that there was 13 per cent of sucrose 

 on August 25, at the time the experiment was begun, and it 

 increased rapidly until November 7 when it reached its 

 maximum 30 per cent. The sucrose then rapidly disappeared 

 until February 11 when the experiment was discontinued, at 

 which time it was 6 per cent. It is of particular interest to 

 note that the starch declined rapidly from August 25 until 

 November 7 when it entirely disappeared, this being the 

 same date when the sucrose reached its maximum. Here 



1 Thatcher, R. W. Enzyms of apples and their relation to the ripen- 

 ing process. Jour. Agr. Res. 5^: 1915: 103-116. 

 ^ Loc. cit. 



^ Browne, C. A., Jr. Penn. State Dept. Agr. Bull. 58. 

 ^Kulisch.S. Landw. Jahrb. 1892. 21:871. 



