i8o 
Journal of Agricultural Research 
Vol. XXIV, No. a 
Table X .—Permeability at the surface and in the region of browning 
[Expressed in ohms resistance} 
Test 
No. 
Majority of readings. 
Extremes of variation. 
Eruit tested. 
In region of 
browning. 
At the surface. 
In region of 
browning. 
At the surface. 
I 
Apples of lots 6 and 9, stored at 
8.3* c. 
1,600 to 1,800.. 
1,600 to 1,800.. 
1,500 to 2,000.. 
1,500 to 2,000. 
3 
Same as (i), but stored at 5® C... 
2,300 to 2,500.. 
2,600 to 2,800.. 
2,000 to 2,600.. 
2,300 to 3,800. 
3 
Same as (i), but stored at 0® C. 
(These lots browned at 0® C.) 
r,ioo to x,3oo.. 
2,300 to 2,500.. 
x,ioo to 1,800.. 
2,200 to 2,800. 
A 
Same as (3), but reading taken in 
trace brown tissue. 
900 to 1,200_ 
2,300 to 2,400.. 
800 to 1,300_ 
3,000 to 2,800. 
5 
Same as (3), but reading made in J 
severely brown tissue. 
600 to 900. 
2,200 to 2,400.. 
500 to X,IOO. ... 
1,900 to 3,600. 
6 
Fruit from black togs, very re¬ 
sistant to browning at 0® C. 
2,200 to 2,600.. 
2,600 to 3,900.. 
3,000 to 2,900.. 
3,300 to 3,900. 
7 
Apples from same tree as bagged i 
fruit, very susceptible to | 
browning at 0® C. I 
1,000 to r,2oo,. 
2,300 to 2,500.. 
1,000 to 1,600.. 
2,000 to 2,700. 
8 
Virginia apples, very resistant to | 
browning at 0® C. ! 
2,500 to 2,700.. 
2,600 to 2,800.. 
2,300 to 2,800.. 
3,500 to 2,800. 
9 
Santa Cruz Mountain apples, | 
very resistant to browning at ! 
0® c. 1 
Tots 3, 5, and 8, very susceptible j 
to browning at 0® C. 
2,200 to 2,500.. 
2,500 to 2,800.. 
t, 7 oo to 2,500.. 
2,300 to 2,800. 
10 
1,000 to 1,500.. 
2,400 to 2,800.. 
x,ooo to 2,000 
x,7oo to 2,800. 
XX 
Same as (xo), but readings made . 
in moderately browned tissue. 
700 to 900.. 
2,300 to 2,600.. 
500 to X,IOO_ 
1,600 to 2,800. 
The figures of Table X show very definitely that there is a change in 
the permeability. At 8.3° C., where browning does not develop, there 
was an increase in permeability. These apples, however, were rapidly 
approaching storage breakdown, due to overripening at this relatively 
high temperature. The permeability had not increased in the apples 
stored at 5® where the ripening process was much slower and where 
the fruit remained free from browning. This was ajso true of the fruit 
at which was resistant to the browning. In the fruit stored ato^ 
that which was susceptible to the browning, there was a greater increase 
in permeability in the interior of the specimens than occurred in the 
fruit stored at 8.3®. The fruit at 0°, nevertheless, was not approach¬ 
ing storage breakdown but incipient browning. In the specimens 
showing browning the permeability continued to increase with the 
advance in the severity of the disease. Therefore these data seem to 
indicate that, just prior to and accompanying the end of the storage 
life •f these apples, there is a very marked increase in permeability, 
regardless of whether deterioration is brought about by storage break¬ 
down or by internal browning. 
INCREASE IN PERMEABILITY DUE TO ESSENTIAL OILS 
If internal browning be due to the accumulation of essential oils or 
similar deleterious substances which change the permeability, these 
oils should also increase the permeability when applied to the surface 
of th0 cut fruit. In order to test this property of these substances, 
several essential oils in great dilution were applied to the fruit about 
the electrodes of the conductivity apparatus. After the initial resist¬ 
ance was taken a drop of the solution Was applied around the electrodes. 
Then the reading of the resistance was made every 5 minutes for a period 
of 20 minutes. The results of these tests were recorded in Table XI. 
