Aug. i6, 1920 Ripening and Storage of Bartlett Pears 475 



loss in tannin material. Analyses of the blossom-end, central, and stem- 

 end portions of the fruit showed slightly more of both sugar and acid 

 in the blossom end, with a slight decrease in the middle and somewhat 

 greater decrease in the stem-end regions. 



Ritter (11) carried on numerous investigations in the ripening proc- 

 esses of fruit. He found that growing fruit in the dark, so long as the 

 fruit only was darkened, had no effect on the chemical composition; 

 but where the surrounding branches and leaves were kept in darkness 

 or semidarkness, there was a marked reduction, not only in carbohy- 

 drates but also in most of the other compounds in the fruit. His figures, 

 however, are based on total grams of the various substances rather than 

 on a percentage basis. He records a progressive increase in the amount 

 of sugar present at successive dates throughout the season and a corre- 

 sponding decrease in acid. These conclusions are based on work with 

 several varieties of apples and pears. 



Riviere and Bailasche (12) also record an increase in sugar and a de- 

 crease in acid in pears, based on analyses at intervals from June until 

 the fruit is ripe. They found further (zj) that defoliating spurs de- 

 creased the size of the fruit while the defoliation decreased the sugar 

 content and increased the acid content slightly. 



Analyses of pears have been made to a limited extent in this country. 

 Dunbar and Bigelow (j) determined the acid present in a number of 

 fruits, concluding that in Bartlett, Idaho, Le Conte, and Kieffer pears 

 citric acid predominates, while for all other varieties malic is the main 

 acid present. 



Thompson and Whittier (17) identified and determined the proportion 

 of the sugars present in a large number of fruits. In Bartlett pears they 

 found levulose to predominate, with some sucrose and a relatively small 

 percentage of glucose. They found, however, that the relative amounts 

 of the various sugars present varied with the state of maturity of the 

 fruit when analyzed. 



Recently Cruess and Stone (2) made rather detailed studies in connec- 

 tion with Bartlett pear ripening in California. Fruit was secured from 

 several sections of California at intervals during the picking season and was 

 tested for size, soluble solids (Balling test), acids, starch, length of time 

 to ripen from date of picking, and general quality of the ripened product. 

 In general, the later pickings gave a slightly higher Balling reading than 

 the earlier ones, and the same lots gave a somewhat higher reading when 

 ripe than when fresh picked from the tree. The acid test tended to fluc- 

 tuate a great deal, so much so that it is rather hard to see a correlation 

 between time of picking and acidity. The amount of starch present in 

 the last pickings, as shown by the iodin test, did not seem to be appre- 

 ciably less than in the earlier pickings. There was a progressive shorten- 

 ing of the time required to ripen the fruit when stored at a constant 

 temperature of 68° F. It was concluded, as a result of a season's work, 



