28 
lens is necessary to measure its diameter. In such extreme cases 
little or no autumn wood is produced in the rings. This tapering 
in growth in the wood rings is most pronounced in acute smelter 
injury, and the date of the first injury is often graphically shown 
by the first lessened annual ring, especially in young conifers. 
On the other hand, coniferous trees injured in the Red Belt 
regions, entirely out of the Smelter Zone, do not as a rule show a 
gradual decrease in the annual increment for the past 5 to IO 
years, as is shown by trees in the regions of acute and chronic 
injury in the Smelter Zone. In the most acute Red Belt injury, 
trees died suddenly after years of rapid and steady growth; in 
less acute forms where the trees recovered, there was little or no 
growth in 1909, followed by increasing growth or increment in 
the wood for 1910 and тогтт. 
The forested area in which the trees were killed by Red Belt 
injury was small when compared to the total area of the forests 
affected. 
In Deerlodge National Forest, in the Smelter TIME no greater 
percentage of the forest has suffered from Red Belt injury than 
has occurred in adjacent forests, in fact, according to the data 
collected by the writer, there is less of this i injury. 
The amount of damage in the same area in the Deerlodge 
National Forest due to wood-rotting fungi is no more than that 
in adjacent forests. Old and mature Douglas firs and pines are 
diseased occasionally with heart rots caused by Polyporus 
Schweinitzii and Trametes pini. On the other hand certain rusts, 
as Peridermium elatinum, P. coloradense, and species of Phrag- 
midium, Melampsora, and Roestelia are almost entirely absent 
from the Smelter Zone around Anaconda, although often present 
in abundance in adjacent forests beyond this zone. 
A great difference in the ability of conifers to withstand the 
effects of smelter fumes has been noted. The species in the 
Smelter Zone named in order of susceptibility to injury are as 
follows: 
I. Abies lasiocarpa (Hook.) Nutt. (Alpine fir). 
2. Pseudotsuga taxifolia (Lam.) Britt. (Douglas fir). 
3. Pinus contorta Loud. (lodgepole pine). 
