Bui. 957, U. S. Dept. of Agriculture 
Trunk and Branches of Pinus strobus, Showing Bark Infections of 
Blister Rust Eaten by Squirrels. 
Photographed by W. H. Snell. 
Fig. 1.— An infected branch which was evidently a young infection that had not yet formed 
secia. Fig. 2.— Infected bark of living tree. Here may be seen the blister-bearing central 
area at the base of the branches in place, while the outer, surrounding, pycmal zone has 
been eaten away. Fig. 3.— Infected bark of living tree. The eaten parts were where pycnia 
were forming. 
