Apr 14.1923 Internal Browning of the Yellow Newtown Apple 
183 
by toxins, these substances are no longer prevented from coming into 
contact. Similarly, the toxins may act upon the inhibitors to inactivate 
them. As a result of this liberation, the tannins of the apple cells 
may be oxidized to a brown by the oxidase which is also present in 
the mature fruit. It has been indicated by Bartholomew (5) that 
changes similar to these precede the blackening of the tissue in 
blacldieart of potatoes. This explanation of coloration based upon a 
change in the permeability is also supported by the fact that before 
browning occurs there is a great increase in permeability of the cells as 
indicated by the conductivity measurements. 
SUMMARY 
(1) Internal browning is a nonparasitic disease of the large isodia- 
metric cells of the flesh of the fruit. 
(2) All Yellow Newtown apples, regardless of where grown, may in 
some years be susceptible to internal browning. This variety when 
grown under conditions prevailing in the Pajaro Valley has proved to be 
much more susceptible to this disease than when grown in other fruit 
regions. 
(3) The later the fruit was picked, the greater the amount of browning 
which occurred in storage, 
(4) No browning occurred even after four to six months storage in 
any of the fruit stored at 8.3° C. or above. 
(5) The browning at the end of six months* storage at 5° C. was very 
limited and mild, and did not detract from the commercial value of the 
fruit. 
(6) At 2.2® C. approximately 70 per cent of the apples showed brown¬ 
ing by April i, figures for each of the three seasons show. During the 
season 1920-21 which was average with regard to browning, only 50 
per cent of the fruit stored at this temperature was marketable on 
April I, 1921. 
(7) At 0° C. practically all the fruit showed browning before April i, 
each season. Only 20 per cent of the fruit stored at this temperature was 
marketable on April i, 1921. 
(8) A lowering by about 3® C. of the mean orchard temperature during 
the growing season, by tenting or shading a tree, greatly increased the 
susceptibility of the fruit to browning. After 4K months* storage at o® 
the fruit of the tented trees showed 25 per cent less of normal specimens 
than that of adjacent trees which were naturally exposed. 
(9) An inc^rease of 4° C. in the mean orchard temperature, by bagging 
individual apples in black cloth during the growing months, markedly 
increased the resistance of the fruit to this disease. The bagged apples 
showed 66 per cent more of normal specimens after months* storage 
at 0° than the naturally exposed fruit of the same trees. 
(10) The browning was greatly reduced by ventilating the fruit. 
(11) The browning was also reduced by impregnating the wrappers 
with oils and waxes which were good absorbents of essential oils. 
(12) By measuring the electrical resistance of the apple tissue, it was 
found that there was an increase in permeability prior to the enci of the 
storage life of the apple, regardless of whether death was due to the usual 
storage breakdown or to internal browning. 
(13) It was demonstrated that essential oils when applied to the apple 
tissue even in great dilution rapidly increase its permeability. 
