EXAMINATIONS OF APPLE STARCH. 93 
The appearance of more intercellular air in the tissues and the con- 
sequent lessening of the specific gravity of the fruit are also correlated 
with the *‘mealiness” of the fruit. It is a matter of common knowl- 
edge that certain apples when ripe are more ** mealy” than others, and 
that in some varieties this quality increases greatly just before decay. 
If a small piece of a mealy apple is carefully crushed and then exam- 
ined under the microscope, it is found that the cells, for the most part, 
have not been ruptured, but have simply been separated from each 
other. This has been made possible by the softening of the middle 
lamelle of the cell walls, which occurs in the last stages of ripening. 
The middle lamella becomes so very weak that under a slight shearing 
force it gives way, thus allowing the adjacent cells to separate without 
rupturing their walls. 
In the earlier stages of the ripening of the fruit a very different 
condition exists, because then the middle lamelle are strong, and the 
cells rupture instead of splitting apart when subjected to pressure. 
The softening of the middle lamella may also be artificially accom- 
plished by boiling. <A striking illustration of this is found in the 
process of making apple butter, in which boiling is continued until the 
cells fall apart when stirred. The readiness with which this occurs 
varies with the different varieties and the decree of ripeness attained. 
This difference in the behavior of the middle lamella in the readiness 
with which it is dissolved by heat the housewife recognizes under the 
common expression of difference of ‘‘ cooking qualities,” and she selects 
apples with regard to this property as well as that of flavor. The 
softening of the middle lamella, whatever its cause, serves, in part at 
least, to explain the difference in the mealy texture of apples which 
may have the same percentage of juice, since in one case the process of 
mastication does not accomplish the rupturing of the cells, which, like 
little bags or capsules, retain the juice. Freezing also appears to 
have a similar softening effect upon the lamella, inasmuch as apples 
which have been frozen have a decidedly mealy texture and soft 
consistency. 
In normal ripening the softening of the middle lamella results in a 
slight change in the contour of the cell wall, so that the cell is more 
regular in outline. The intercellular space is increased, and, as there 
is usually but little liquid to fill the cavity, the amount of intercellular 
air is increased. When viewed under the microscope, the presence of 
air in some varieties is very noticeable indeed when nearly ripe, while 
in the greener condition it is but little in evidence. 
An experiment was conducted to show the difference in the readi- 
ness of disintegration (dependent on the softening of the middle 
lameila in the same fruits) under different conditions of storage. 
Cubes of as nearly the same size as possible were cut from two sam- 
ples and placed in test tubes with a given amount of water. One set 
