606 BULLETIN 347 
logs or tree parts outside the affected regions: (1) ascospores will ger- 
minate after having been kept dry for two and one half years; (2) conidia 
will germinate after having been kept dry for at least a year; (3) mycelium 
retains its vitality after having been kept dry for at least ten months; 
(4) perithecia, after having been kept dry for seven months, will again 
eject spores on being moistened. 
Peeled timber may serve to carry the fungus; for the mycelium, which 
penetrates at times to the fifth annular ring of the wood, will under moist 
conditions produce superficial pycnidia and spore horns on the surface 
of the wood. 
There are chances, of course, that even a strict quarantine on nursery 
stock or chestnut products will not eliminate all the means of introduction 
into a new territory. The fungus, in the form of either mycelium or 
spores, may be carried on or in other plant parts or by birds, wind, or 
other uncontrollable agents. 
Eradication measures 
There are two kinds of conditions under which eradication measures 
may be carried out, namely, arboricultural conditions and forestry con- 
ditions. In the case of orchard and ornamental trees the principles of 
sanitation and tree surgery have been advanced for the control of the 
canker. But even as early as 1908 Murrill says these means are without 
avail. Vast sums of money were expended by individuals in order to 
save such trees in cities and on private grounds in the regions first affected. 
Failure attended all attempts. This was largely due to four reasons: 
(1) the work was done by commercial tree surgeons who had had no 
special training; (2) it is impossible to find and remove all affected parts 
of a diseased tree, especially incipient infections and cankers under rough 
bark; (3) reinfection is constantly possible; and (4), a reason not the 
least in the majority of cases, the fact that the mycelium entered deeply 
into the wood was ignored, and the cankers renewed growth by the 
mycelium growing from the wood back into the bark. The last-named 
fact has been brought out by experiments conducted by Collins 
(x912 a) and by members of the staff of the Pennsylvania Commission 
(r912 b:2). : 
The removal of dead and dying trees and of all refuse from the surgical 
operations is necessary. Also all wounds must be protected immediately 
by an enduring covering (Fig. 97, page 5098). Ample suggestions in 
regard to surgical methods are given by Metcalf and Collins (1911: 18-20), 
Collins (19124), Pennsylvania Chestnut Tree Blight Commission 
(1912 b), and others. A later report (Pennsylvania Chestnut Tree 
