Jan. 5.1924 
Physiological Studies on Apples in Storage 
27 
At the end of the run samples of the atmosphere from the interior of 
the apples (from intercellular spaces) were extracted and analyzed. 
The method employed was that previously described by one of the writers 
( 20 ). These data, which show the actual atmospheric conditions pre¬ 
vailing inside the fruit, where the respiratory activity takes place, are 
recorded in Table V. 
Table V .—Analyses of atmosphere from intercellular spaces of normal and coated Wine- 
sap apples at J2° F. ( o° C.) 
Experiment No. 
Per cent 
COs. 
! 
; Per cent 
O2. 
Per cent 
N2 by 
difference. 
x. Control; no treatment. 1 
2 .3 
i 
18. 4 
79 - 3 
2. Medium paraffin coating.j 
II. I 1 
12. 6 
76.3 
3. Light oil coating.■ 
IO. I 
10. 4 
79 -S 
4. Heavy oil coating. 
1 
12.4 
i 
2.9 
84. 7 
These data show that in all cases there was a marked increase in C0 2 
within the tissue following coating and a marked decrease in 0 2 . An 
abundance of oxygen appeared to be present, however, in all lots except 
those heavily oiled. The fact that the light coatings, which resulted in 
a large increase of C0 2 in the tissues as compared to the controls, also 
resulted in a marked decrease in respiratory rate indicates that the 
C0 2 directly inhibited respiration. The fact that the quantity of 0 2 used 
per cubic centimeter of C 0 2 given off was actually greater in the coated 
fruits than in the controls further indicates that, at least in the lightly 
coated fruit, the 0 2 supply was not the limiting factor in the respiration 
rate, but rather that respiration was inhibited by C0 2 accumulation. 
This will be further discussed under the subject of the effect of C0 2 on 
fruit ripening. 
RESPIRATION AT 64.5° F. (l8° C.) 
Magness ( 20 ) has shown that the C 0 2 in the intercellular spaces of 
normal apples increases when the fruit is held at higher temperatures, 
and that the 0 2 within the tissues correspondingly decreases. Conse¬ 
quently, the effect of coating the fruit with oil or paraffin would appear 
to be accentuated at higher temperatures. C0 2 output and 0 2 intake 
were measured on three varieties, and after various treatments, while 
being held at 64.5° F. (18 0 C.). Results of these respiration tests are 
recorded in Table VI. 
The data reported in Table VI are of much interest in interpreting the 
exact effect of coating the surface of the fruit with substances reducing 
permeability to gases. It will be noted that all cases of coating the fruit 
(experiments 2, 6, 11, and 12) resulted in greatly decreased C 0 2 output, 
and greatly decreased 0 2 absorption as well. Metabolic activity in these 
lots was reduced to only slightly over half that shown in check lots of 
fruit. This is in accordance with the slower softening and longer reten¬ 
tion of green color in these coated fruits. Also of very marked interest 
is the respiratory ratio, or ratio of C 0 2 given off to 0 2 taken up by various 
lots of fruit. Gerber ( 12 ) reported that at 18 0 C. the respiratory ratio was 
practically unity in apples. In other words, one molecule of C 0 2 was 
given off per molecule of 0 2 absorbed. This would be the case if reduc- 
