DISTRIBUTION OF CERTAIN SUGARS IN BOSC PEARS

Since an investigation of the various sugars present in winter pears was in progress at this station, it was thought desirable to determine in a preliminary way the variation in the sugar content of the various portions of the fruit, and from this information to decide as to the best method of taking samples of the pear. The effort was made to divide the fruit into natural regions on the basis of anatomical characteristics rather than on the basis of some arbitrary geometric differentiation. KELHOFER (6) has noted that in the Siebenmannsbienen pear sugar and acid were higher in the central fleshy portion of the fruit than in the core or peel. Tannin was observed in greatest concentration in the peel while small amounts were noted in the core region. Analyses of blossom end, central portion, and stem end showed slightly more sugar and acid in the blossom end than in the central portion, and still smaller amounts in the stem end of the fruit. ALLEN (1) in reporting on the electrical conductivity of pear tissue showed that there were quite marked differences in the specific resistance of the flesh of the cortical and pith regions of Bartlett pears, and noted that the resistance of the flesh of these regions changed as the fruit ripened after harvest. While a number of workers have investigated the amounts of sucrose, dextrose, and levulose in pears both during the growing season (5, 14) and during storage (4), none have reported the concentration of these sugars in the several regions of the fruit. SMITH (13) has recently published a comprehensive report dealing with the course of stone cell formation in pear fruits and has shown the changes in total sugars, starch, hemicellulose, pectins, and other constituents during growth and subsequent storage. He has pointed out the importance of expressing the results of analyses of growing fruits in terms of the actual amounts of the various constituents per fruit rather than in terms of concentration, and has suggested that sampling which included the whole fruit would be more representative in sugar content than that taken only from the midsection if it were established that marked differences in sugar concentration existed in the various parts of the fruit. CRIST and BATJER (3) have reported on the nature and occurrence of "grit cells" in pear fruits and have discussed their probable function as well as that of the stony sheath of these cells surrounding the core of the fruit.