179 
Apr. 14,1923 
?")^ternal Browning of the Yellow Newtown Apple 
susceptible. In the Yellow Newtown, apparently, the region of greatest 
susceptibility is in the flesh, while in those varieties that scald readily, 
it is at the surface. 
If internal browning and apple-scald are caused by the accumulation 
of essential oils, which can be removed by ventilation or by absorption, 
the question arises as to why the preventive action of ventilation and 
absorbents is less marked in the control of internal browning than in 
apple-scald. This difference in the effectiveness of the prevention is 
undoubtedly due to the fact that apple-scald is the result of the accumu¬ 
lation of deleterious substances on the surface of the fruit where the 
absorbent Gan be brought close to them. Internal browning, on the 
other hand, is caused by an accumulation of the deleterious substances 
deep in the tissues, from whence they can be removed only by the very 
slow process of reducing their concentration at the surface, thereby 
inducing them to diffuse outward. 
INCRKAS^ IN PlSRMEABIUTY PRIOR TO THE APPEARANCE OP INTERNAI^ BROWNING 
If internal browning is due to the action of some deleterious substance 
which tends to acctunulate in the flesh of the apple under storage condi¬ 
tions, there should be some evidence of its action before the browning 
actually occurs. By this it is meant certain alterations will occur in 
the cells which will permit the browning to take place. Possibly the 
most important, as well as the most probable, change which could take 
place is that of altering the permeability. 
The changes in permeability were determined by measuring the resist¬ 
ance offered by the tissue to the passage of an electric current. Elec¬ 
trodes for this purpose were patterned after those used by Small (15). 
The electrodes were mounted so that they stood mm. apart and in 
such a manner that they would be pressed cm. into the tissue. 
The measurements were made by the Kohlrausch method. The fruit 
was cut as in making the observations upon the browning and the elec¬ 
trodes were then pressed into the various regions in which measurements 
were to be made. The readings were made by bringing the minimum 
point to the same position on the bridge each time. These reading^, 
therefore, indicate only the relative resistance of the different regions in 
the fruits. (For the iirformation of some readers it may not be amiss to 
state that a decrease in the resistance offered to the passage of an electric 
current is interpreted to mean an increase in the permeability of the cells.) 
Since it was impossible to obtain the above apparatus until late in the 
season, the results which are recorded in Table X give only one stage in 
the permeability changes that occur during the course of an entire 
storage season. All the measurements, wirfi the exception of those 
given under tests No. 4, 5, and ii, were made in tissue which showed no 
browning. 
