Nov. 12, 1917 
Jonathan-Spot and Scald of Apples 
■ 3 i 3 
accumulation of carbon dioxid, but this does not seem probable. The 
tops of the moist chambers fitted loosely, and any increased accumula¬ 
tion in carbon dioxid would undoubtedly have been largely balanced by 
an increased air exchange. It is also probable that a higher percentage 
of carbon dioxid would be required to give a particular degree of inhi¬ 
bition at a high temperature than at a low one. Kidd (13) found that 
a rise of 10 degrees in temperature necessitated, roughly, the presence of 
three times as high a partial pressure of carbon dioxid to cause an inhi¬ 
bition of germination in the seeds of Brassica alba . It seems probable 
that the more rapid development of apple-scald at the higher temper¬ 
atures should be attributed to the more rapid procedure of respiratory 
activities that have become abnormal rather than to any greater inhib¬ 
itory action of the accumulated carbon dioxid. 
Scald has not occurred at 30° either in moist cnambers or in open 
containers. This may have been due to the fact that the carbon dioxid 
oxygen ratio did not become high enough to cause a sufficiently disturb¬ 
ing effect upon respiratory activities at such a high temperature. The 
skin color changes, however, were peculiar at this temperature, indicating 
the possibility of other causes for the absence of scald. 
Scald occurred at o° in the open containers, but not at 5 0 or at any of 
the higher temperatures. This contrast might be attributed to the 
greater inhibiting value of carbon dioxid at low temperatures, but the 
relatively small amount of this gas found in the o° box has not furnished 
any support for this theory. It is the opinion of the writers that the 
development of scald at o° under conditions that have not produced it 
at higher temperatures should be at least partly credited to the depressing 
effect of the low temperature itself. It is especially interesting in this 
connection to note that scald has not become evident while the apples 
were at o°, even when it has been actually produced at that temperature. 
The skin sometimes took a slightly faded watery appearance, but it did 
not turn brown till the apples had been removed to a warmer tempera¬ 
ture. The inhibition of the browning at o° should probably be attributed 
to the suppressing effect of the low temperature upon the oxidizing 
enzyms of the apple skin, and it would certainly not be surprising if a 
temperature that has inhibited oxidation color changes should also have 
its peculiar effects upon the oxidation connected with respiration. 
Scald apparently results from some effect that acts as a cumulative 
agent. Its rate of development is influenced by temperature, by the 
maturity of the fruit, and within certain limits by the degree of aeration, 
but it has not been found possible to produce it in a short period of time 
by the intensification of any favoring agency. 
Apples stored under conditions favorable to the development of scald 
but removed to other conditions before a certain critical period is reached 
apparently do not retain their accumulated scald tendencies. A striking 
