494 Journal of Agricultural Research voi.xix, No. w 



the pear tissue to pressure as the season advances. The pectose material 

 is generally thought to be largely responsible for the thickening and 

 cementing together of the cell walls and hence for the firm texture of fruit. 

 The association of the decrease in amount of this and related material 

 with decreasing resistance of the tissue to pressure is evidence in support 

 of this theory. 



The temperature at which the fruit was stored has no marked influence 

 on this material. A comparison of the lots picked at the same time 

 and stored under the different temperature conditions (Tables I-IV, 

 columns 16-18) shows little variation. 



influence; of time of picking and temperature of storage upon 

 percentage of dry weight 



In this report, sugars and acids have been figured to percentage of the 

 wet weight, as it is considered that wet weight rather than dry weight 

 percentage will give the most accurate index of quality. The data for 

 total dry matter in the fruit are of much importance, however, especially 

 in connection with the pear dehydration industry, and for the purpose of 

 throwing light upon the question of how much shrinkage, due to loss of 

 moisture, occurs in the fruit during storage. 



From the data on dry weights presented in Tables I to IV it will be 

 noted that while considerable variation seems to occur in various indi- 

 vidual lots, one or two things stand out as of special interest. In the 

 California fruit, in which the first pickings were made much in advance 

 of the commercial season and when the fruit was very immature, the 

 percentage of dry weight was higher in the earliest lots than it was in 

 those lots picked during the main commercial shipping season, a month 

 later. (Tables I and II, columns 19-22.) Toward the end of the season, 

 however, the percentage of dry matter increased until the last pickings 

 gave the highest dry-weight figures of all lots. The first pickings of the 

 Oregon and Washington fruit (Tables III and IV) were made at a some- 

 what later relative date than the first pickings from California, so the fact 

 that the earliest pickings show a low dry weight is in accord with the 

 data for California sections. 



Thus it is at once apparent that, for purposes of dehydration, pears left 

 on the tree as long as possible will give not only the greatest tonnage, 

 because of the size of the fruit, but will also give the greatest weight of 

 the dried product per pound of green weight. Consequently, it is of 

 special importance that pears intended for dr5dng be left on the trees as 

 long as possible. 



If the dry weight of the fruit at the time of picking is compared with 

 the dry weight of the same lots when they come from storage fully ripe 

 it is seen that for well-matured fruit there is very little moisture loss dur- 

 ing storage. A comparison of the earliest lots from Suisun and from 

 Sacramento (Tables I and II) is interesting in that the Sacramento fruit 

 was wrapped, whereas that from Suisun was loose in the box and un- 

 wrapped. There is no increase in dry weight in the Sacramento fruit, 



