Effect of Soil Conditions 61 
more readily than others. These latter, like the Swamp Oak, 
Bald Cypress and Alder, especially when they have once 
adapted themselves to swampy life are at a great disadvan- 
tage if the conditions are suddenly changed. It is, there- 
fore, possible that in newly planted trees any ailment is 
merely due to change from one set of conditions to another, 
to which the tree is not as yet adapted. Thus a tree moved 
from a shady position to one of more intense light will suffer 
for a time until the foliage is adapted to the new environ- 
ment. 
In passing it is interesting to note that even a physically 
moist or wet soil may be physiologically dry, that is to say, 
the water may not be available to the rootlets. This is 
the case in swamps where the water is saturated with humic 
acids from the decay of vegetable matter, these acids having 
a greater attraction for the water than the rootlets can exer- 
cise. Here we see quite frequently the disease called sfag- 
head, which consists in the drying of the top due to deficient 
water-supply at the root. 
It is, therefore, necessary to be cautious in the attempt to 
diagnose and correct water conditions. 
The death of the top, top dryness or staghead, is gradual, 
the lower branches remaining green, their annual shoots, 
however, becoming shorter. It is a result of drouthy con- 
ditions at the root, which may be caused in various ways, 
other than the one just cited. In forests and parks, by cut- 
ting out or burning the undergrowth and by severe trim- 
ming, ihe sun is given access to the ground. As a consequence 
the decomposition of the litter and humus which covers 
the soil proceeds more rapidly, while at the same time on 
account of the increased light supply the foliage becomes 
more active. Stimulated by the increased food elaboration, 
all the benefited trees at first grow more vigorously and their 
