296 
STRUCTURE AND LIFE HISTORIES 
dollars. The mycelium of the fungus that causes it 
(Endothia parasitica} grows underneath the bark, and 
for this reason it is practically impossible to check it 
FIG. 218. Chestnut blight. Portion of a branch of an American chest- 
nut (Castanea dentata), which had been artificially inoculated with the 
spores of the chestnut-blight fungus, Endothia parasitica (Murr.) Anders. 
The white areas are infected spots. (After W. A. Murrill.) 
by spraying, as the bark protects the mycelium from all 
known spraying solutions. The fruiting pustules of the 
fungus form on the surface (Figs. 218 and 219). The 
