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and not from the effect of a direct and immediate injury, which 
killed the leaves by drying them out in a short space of time, com- 
pletely defoliating and killingthe trees, as in the Red Belt. 
The Red Belt injury occurred while there was a deep snow in 
most of the forests affected, and the younger parts of small pines 
and firs were injured only above the snow, the older parts covered 
with snow remaining green and healthy. Оп the other hand 
young trees suffering from acute smelter injury die in a reverse 
order, the lower limbs, and the older leaves dying first, the upper 
limbs and younger leaves last, the snow affording no protection 
in summer. 
The less acute form of injury by smelter fumes usually known 
as chronic injury, causes a much slower defoliation of coniferous 
trees than the acute form. In lodgepole pines and firs, the 
leaves gradually lose their bright green color and become chlo- 
rotic, usually with a reddish tinge. All gradations between this 
appearance in typical chronic injury and the brightly reddened 
needles the acute form are found. In both forms the older 
needles are killed first, but in the chronic form, death takes 
place more slowly than in the acute. 
In the less acute forms of Red Belt injury few terminal buds 
or twigs were hurt and only the leaves were affected. The leaves 
were reddened where the tips were killed, and in many instances 
the trees were nearly defoliated by the death of the needles in 
1909. New green leaves, however, were put forth from the 
terminal buds of the less severely injured trees; some of these 
were chlorotic in appearance. Slightly injured trees lost only 
a portion of the foliage and recovered their growth at once. 
A third form of smelter injury has been inaptly named invisible 
injury in Germany. This consists in a gradual and premature 
defoliation of the trees accompanied by a slight chlorosis and 
change of appearance in the leaves. This form checks the growth 
of the trees, and often at a later date assumes chronic form. 
In all the forms of smelter injury in the smelter zone about 
Anaconda the general effect has been to form decreased annual 
wood rings year by year as the defoliation becomes more com- 
plete, until the width of a ring is often so slight that a powerful 
