6 NEW YORK STATE MUSEUM 
the central part of the State and about Albany resulted in an ex- 
planation of the damage. 
July was ushered in by about ten days of unusually hot weather, 
following a considerable period of drought, with high temperatures 
prevailing on some days. While the week of July 6th was a little 
cooler, the drought continued, and in fact the precipitation for the 
entire summer was far below normal. On July 12th and 13th there 
occurred a strong, hot and dry west and southwest wind, which 
continued with greater or less strength for several days. 
The maple is well known as a very shallow rooted tree and the 
effect of the dry wind upon transpiration in the leaves is very 
marked in the case of any tree. It is apparent that the period of 
drought preceding the early part of July had reduced the available 
water of the soil to a minimum, so that the factors favoring trans- 
piration (that is, dry, hot winds) which followed, greatly exceeded 
the power of the trees to absorb water from the soil which was 
actually deficient in moisture. Such a condition of affairs was 
particularly active in the case of maples along streets, highways, 
in parks or other situations where the soil was not protected from 
drying out by litter or undergrowth. 
The leaves of the maple being unable to maintain the high rate of 
transpiration necessary under such conditions, were susceptible to 
the chemical activity of the sun’s rays, causing the bronzing effect, 
a chemical change of the cell contents, somewhat analogous to what 
takes place normally in autumn when the leaves turn to shades of | 
red or yellow. In many cases this state was followed by withering 
and death of the leaves, as sufficient moisture was not available to 
revive the leaves and to maintain their turgidity, which alone keeps 
them under ordinary conditions from collapsing. 
That the dry weather and dry winds mentioned were responsible 
for the widespread damage seems probable also from the fact that 
the trees in situations of permanently damp soil, as in deep wood- 
lands, suffered little or not at all; and of the trees affected, the 
greatest damage seems to have been on the side exposed most 
directly to the wind. Elms, having deeper-going roots, did not 
suffer so much as the maples, although considerable damage to their 
foliage was noticed in the case of some trees growing in dry soils. 
The leaves of the elm also possess a thicker epidermis and are 
better adapted by structure to withstand the factors like wind and 
heat which favor excessive transpiration and its subsequent damage. 
The injury to maple and elm foliage thus noted is not likely to 
