a 
CANKER GROWTH ON ABIES BALSAMEA 29 
scription: ‘‘ Described from specimens in Phillip’s Elv. Brit., no. 
66. The size of the spores—5 x 2.5 #—as given by Phillips in 
Disc. Brit., is certainly too large. I have never found them above 
3 » long.” 
The spores of the specimens found in Hungary were 3 x 2.5 4; 
also smaller than the size given by Phillips in his description, but 
of same size as spores of specimens found in Minnesota. 
No European specimens of D. resinaria have been examined 
by the writer, but the descriptions of it correspond so closely with 
the Minnesota Dasyscypha, that there can be little doubt about the 
two being the same species. 
THE CANKER 
The characteristic smooth bark of Adies balsamea, becomes 
rough at the canker spot, by the formation of ridges and bark 
projections, soon after the infection has taken place. The outer 
bark (peridium and epidermis) does not become hypertrophied, but 
is broken through, and scales off, sooner than normally, on ac- 
count of the increased growth of the inner layers of the bark, 
which become hypertrophied. 
Primary Cortex (Mippie Bark) 
In the bark of the canker, the periderm as well as the primary 
cortex, and outer layers of the secondary cortex, are very soon 
cut off by the formation of a new phellogen layer. This causes 
the death of the cut-off layers of the bark which dry up sooner 
than in the normal. The resin-canals are also cut off and dis- 
turbed and their resin contents begin to diffuse into the surround- 
ing tissues, but mostly collect in the resin-vesicles or “blisters,” 
which are also formed sooner in the primary cortex of the 
canker than in the normal bark. The vesicles of the canker 
depart from the normal, especially in their size (figs. 7 and 
8), being either abnormally large or small. The resin of the 
canker vesicles is forced out by the increased pressure on the 
vesicle, by the shrinkage of the surrounding dead layers of the 
bark, cut off by the new phellogen. The resin thus forced out 
runs down the trunk of the tree, the more volatile substances 
evaporating, leaving the solid resin, which hardens and gives the 
