Nov. 12, 1917 
Jonathan-Spot and Scald of Apples 
291 
have increased in a very gradual manner over a period of one or two 
months. 
20.0 
EFFECT OF AERATION AND HUMIDITY ON JONATHAN-SPOT 
In most of the temperature experiments part of the fruit was placed in 
moist chambers and part in wire baskets or other open containers. The 
tops of the moist chambers fitted • 
loosely, nearly always leaving cracks of 
0.5 mm. or more, yet preventing a free 
circulation of air. The apples in the 
open containers were freely exposed to 
the air of the boxes, which was kept in 
circulation by fans. Anemometer tests 
showed that the movement of the air 
was in no case as rapid as yi mile per 
hour. Gas analyses reported later under 
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TEMPERATURE CERT/GRAPE 
Fig. 5. —Graphs showing the effect of temper¬ 
ature on Jonathan-spot at the end of 4, 5, 6, 
7, 8,10,12, and 14 weeks. The apples were 
of the same lot as those of figures 2 and 4 but 
were greener than the former and riper than 
the latter. They were stored in moist cham¬ 
bers with moist filter paper added. The ex¬ 
periment was started on October 6, 1916. 
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TEMPERATURE CE/VT/GRA&E 
Fig. 4.— Graphs showing the effect of temper¬ 
ature on Jonathan-spot at the end of 4, 5 , 
6 , 7, 8, 10,12, and 14 weeks. The apples 
were of the same lot as those of figure 2 but 
were greener. They were stored in moist 
chambers with moist filter paper added. 
The experiment was started on October 6, 
1916. 
the head of “Apple-scald” (p. 300) 
showed that the amount of carbon 
dioxid in the free air of the boxes was 
little above normal, while that in the 
moist chambers was sufficiently high to 
have a distinctly depressive effect upon 
respiration. 
The effects of aeration and humidity 
upon Jonathan-spot are brought out 
in figures 6 and 8. In figure 6 curve A shows the amount of the disease 
developed in moist chambers to which wet filter paper had been added, 
and curve B the amount developed in the open containers. The air 
in the former case was practically saturated, while in the latter case 
that at io° had a relative humidity of 55 to 70 per cent and that at 25 0 
was probably still drier. The experiments recorded in figure 8 were 
more carefully controlled. Curve C shows the amount of Jonathan- 
