birefringent bodies. Jonathan, Stayman, and Golden Delicious had 

 lesser staining capacity (more prominent pits), greater extent of 

 rupture, and several observed examples of birefringent bodies. 



After prolonged storage, the tissues showed a reduced staining 

 capacity and a greater incidence of ruptured cell walls in sections. 

 Cell wall thickness apparently did not change during storage, accord- 

 ing to the measurements. 



In sections of tissues that had been steamed before fixing, starch, 

 if present, was found in a partially or wholly gelatinized condition 

 (pis. 3, F; 4, F). Cell walls and middle lamellae were paler, other 

 pectic structures were more prominent, cell wall rupture was generally 

 more extensive (pi. 1, B, C, E, G, I), and birefringent bodies or 

 "flakes" were more frequent. Flakes of the cortex were usually 

 larger than those of the hypodermis, they occurred singly, and many 

 seemed to be in the middle lamella; they may not all be of the same 

 origin as those of the hypodermis. Cell wall thickness apparently 

 did not change according to the measurements. The cortex of De- 

 licious apples retained the greatest staining capacity, showed the 

 fewest instances of flaky breakdown, and had little or no increase in 

 ruptured cell walls. Golden Delicious, Rome Beauty, and Stayman 

 samples had relatively more instances of flaky breakdown in the 

 cortex. Separation of cortex cells due to cooking was not observed 

 in the sections. When sections were treated with histochemical 

 reagents, cortex cell walls reacted similarly to hypodermal cell walls. 



Chemical findings 



Results of analyses for total acidity, pH, reducing sugar, total 

 sugar, total pectin, pectic acid, and moisture content are given for 

 raw apples by crop year and maturity, and before and after storage 

 (tables 5 and 6). Results of analysis of variance for the various 

 chemical constituents are given in table 7. Correlation coefficients 

 between the chemical constituents of mature apples are presented 

 in table 8. 



Total Acidity 



The six varieties of mature apples included in this study differed 

 significantly in total titratable acidity. As shown in figure 3, before 

 storage of apples, Stayman had the highest value of 91 ml. of N/10 

 sodium hydroxide required to neutralize the acid; Jonathan had a 

 value of 84, Winesap 72, Golden Delicious 57, Rome Beauty 44, and 

 Delicious 19. Storage caused a significant decrease in total acidity 

 of the apples. After 7 months at 40° F. total acidity values of the 

 varieties ranged from 65 to 14 with Stayman, highest and Delicious, 

 lowest. Total acidity of apples stored at 40° was not significantly 

 different from that of apples stored at 32°. The decrease in total 

 acidity of apples during storage agrees with earlier reports of Magness 

 and associates (25) and Vecher and Bukin (49). In the latter report 

 it was stated that a decrease in total acidity was caused by oxidation 

 in the normal respiration of the fruit. 



Total acidity of immature apples like mature apples showed 

 significant differences related to variety and storage time. Of the 

 four varieties of immature apples studied, Stayman was highest, with 

 values of 88 before storage to 60 after storage for 7 months at 40° F. 

 and Delicious lowest, with a value of 23 which decreased to 8 after 5 



23 



