448 BOTANICAL GAZETTE [ DECEMBER 
branch. It will be observed that the loss during the first forty- 
eight hours was rapid in both cases, namely, 258" from the 
healthy branch and 30 from the diseased. At the end of this 
time both the healthy and the diseased leaves showed an evident 
lack of water. This lack, however, was more marked in the dis- 
eased leaves, the tips of many of which were shrunken above the 
diseased area. This lack of water had caused the stomata of 
both the healthy and the diseased leaves to close as far as possi- 
ble, thus cutting down the loss through them to a minimum. 
During the next forty-eight hours the healthy branch lost 4.5 
while the diseased lost 88". It was evident that from this time 
the leaves were able to obtain very little if any water from the 
stem. During the next three periods of forty-eight hours each 
the healthy branch lost 5, 4.5, and 2.58 respectively, while 
during the same periods the diseased:branch lost only 3.25, 
3, and 08", The leaves of the diseased branch were completely 
dry at the end of 186 hours, while the healthy plant was not 
yet dry at the end of 240 hours, but was still losing at the rate of 
1.58" per day. The more rapid drying out and death of the dis- 
eased leaves than of the healthy is therefore evident. Asa fur- 
ther evidence of this the following experiment may be cited: 
Six pairs of leaves, three of which were diseased and three 
healthy, were removed from the same branch and immediately 
cemented into a piece of cork to keep them from tipping oV¢™ 
Weighings were then made at given periods, with results as shown 
in the accompanying diagram, the broken lines representing the 
diseased and the unbroken the healthy leaves. It will be seen that 
the average loss for the healthy leaves for the first twenty-four 
hours was about 5™, while from the diseased leaves it was 16. 
This rate of loss continued nearly constant for the healthy leaves 
for 174 hours, while the loss from the diseased leaves kept gradually 
diminishing. At the end of 120 hours the healthy had lost about 
24™. and the diseased 32™8. The latter were now becoming quite 
dry, so that during the next twenty-four hours they lost an et 
age of only 3™8, while the healthy lost about II mg At the oe 
of this period (174 hours) the diseased leaves were air-dry, a0 
