STUDIES OF PHYSICAL AND MORPHOLOGICAL CHANGES IN 
BARTLETT PEARS 1 
Andrew Edward Murneek 
(Received for publication October 6, 1922) 
Introduction 
During the comparatively short period of development and maturity, the 
pear fruit passes through a series of profound morphological, physical, and 
chemical changes. While the gross features of most of these alterations are 
more or less observable, the more detailed changes, such as may have taken 
place during a brief interval of time, are rather difficult to measure or even 
to approximate. Yet in all harvesting, transportation, and storage opera¬ 
tions with most of the commercial varieties of pears, these changes assume a 
profound importance, for they have a direct bearing on both the eating and 
the keeping quality of the fruit. This is of particular significance in view of 
the fact that the pear is a highly perishable product. Hence of late, because 
of the rapid expansion of our marketing operations, particularly with fruit 
from the Pacific Coast, the subject is receiving an ever-increasing emphasis. 
There is a growing demand for more extensive and more detailed information 
in this field as a logical addition to some of the groundwork already laid by 
a number of more or less correlated investigations. 
Review of Literature 
As a result of the studies of Kulisch (9), Ewert (2), Kelhofer (6), Ritter 
(15), Riviere and Bailhache (16), and other European investigators, there 
has accumulated considerable information on the chemical changes in the 
pear as affected both by seasonal differences and by artificial alterations of 
a number of environmental factors. In this country, Dunbar and Bigelow 
(1), Thompson and Whittier (17), and Magness (11) have made valuable 
contributions on the subject. All of these investigations, however, have 
been based largely on changes of the cell contents and only indirectly on 
those of the structural part of the tissues. This is but natural if we re¬ 
member that our present knowledge of the chemistry of the principal 
substances of the cell walls is very imperfect. So, too, the culinary prop¬ 
erties of the pear fruit being determined primarily by the amount of sugars, 
acids, and tannin present, these substances have naturally received first 
consideration. Though most of our present chemical data have been 
secured from samples taken at considerable intervals of time, still they may 
1 Published by permission of the Director of the Oregon Agricultural Experiment 
Station. 
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