182 
Journal of Agricultural Research 
Vol. XXIV, No. 2 
The accumulation of essential oils or similar deleterious substances 
also seems to be rather closely linked with the weakness in these apples 
that shows up in storage. This is indicated by the great reduction 
in the amount of browning that is brought about through the employ¬ 
ment of air circulation or the impregnation of the wrappers with good 
absorbents for these substances. It has been further demonstrated 
that the permeability of the cells, which is the most probable change 
that might precede this browning or similar reactions, is increased very 
rapidly by essential oils when applied even in great dilution to the apple 
tissue. It was also found that there was an increase in permeability 
prior to and accompanying the death of the cells in the apple regardless 
of whether death was due to the usual type of storage breakdown (which 
is the result of overripening) or to internal browning. 
The data obtained upon the relationship of temperature and the 
accumulation of essential oils or similar volatile substances to the brown¬ 
ing, although not conclusive, point to several possibilities concerning 
the cause of this disease. When these apples are grown at a mean tem¬ 
perature as low as that of the growing season of the Pajaro Valley, they 
may fail to develop normally, hence when they are placed in storage the 
flesh of the fruit exhibits a susceptibility to injury tibrough the action of 
the volatile emanation of the apple. This is indicated by the behavior 
of the fruit from different regions as well as by that from under the tent 
and in the black bags. This lower temperature may not only affect the 
development of the fruit but also apparently influence the production 
or accumulation of the volatile substances which are immediately respon¬ 
sible for the browning. This becomes apparent when the great difference 
in the amount of browning which developed at the several storage tem¬ 
peratures is taken into account. Seemingly there is a greater produc¬ 
tion of these substances at the lower temperatures, or otherwise they 
must accumulate more rapidly in those regions of the torus that are first 
to show the browning. 
The reduction in the development of the browning by the use of gas 
absorbents also indicates that these volatile substances are present in 
injurious amounts at the lower temperatures under the ordinary condi¬ 
tions of storage. The more rapid accumulations of the deleterious 
substances may seem the more probable way of accounting for the injuri¬ 
ous amount of these substances when the decrease in their volatility 
and the decrease in the permeability of the tissue at the lower tempera¬ 
tures is considered. However it is likely that there is also a greater 
production of these substances under the somewhat abnormal conditions 
of the lower temperatures of storage. 
The nature of the process which results in the browning becomes of 
interest in connection with the preceding possibilities as to the cause of 
this trouble. Plausible explanations of this process could possibly be 
ascribed to an increase in the permeability of the protoplasm which 
permits the enzyms and their substrates to mix, or to the inactivation 
of some inhibiting substance. These changes might be brought about 
by the accumulation of certain substances such as Sie essential oils which 
are produced by the apple in storage and which apparently have a toxic 
effect upon the protoplasm of the cells. 
In the normal cells the enzyms are prevented from acting upon their 
substrates by inhibitors or through lack of contact due to the possibly 
impermeable nature of the phase surface of the protoplasm. WTien 
the phase arrangements in the protoplasm, however, are acted upon 
