The Biology of Polyporus Pargamenus Fries — 183 
The majority of the fire-killed trees had sent up a good 
coppice growth but even this new growth will be subjected 
constantly to infection and as soon as any injuries occur to 
any of these new trees they will, without fail, be attacked by 
this sap-rotting fungus. The majority of the standing timber 
on this tract is too small to serve for anything but fence posts 
and cordwood, but even the possibility of profitable returns 
from these sources has been neglected by the owner. Thus 
will the infected timber remain standing for a number of 
years and continue to be a place of propagation and source 
of new infections, thereby endangering all other hardwood 
timber for miles around. 
Control of the Sap-rot Caused by Polyporus Pargamenus 
In forest pathology we have to deal with trees under two 
cultural types: Tirst, the trees in the forest; second, shade, 
park, and ornamental trees. When we come to consider the 
question of commercial control, which is the principal aim 
and end of forest pathology, we can see that we have two 
very different lines of attack, which are governed entirely by 
commercial considerations. A shade or ornamental tree has 
great individual value and is under constant observat#on, or 
at least it should be. In this case we can employ in the pre- 
vention of disease the methods of control that have been 
evolved with such remarkable success in tree surgery practice. 
When we consider diseases of the forest, however, commer- 
cial conditions are quite different. It is no longer possible 
to give the individual tree a large amount of attention. We 
must consider the forest en masse. This being the case, it is 
apparent that there is indicated for forest pathology a line of 
evolution quite distinct from that which characterizes the 
appheation of forest pathology in arboricultural practice. 
For the present this development will be comparable to what 
a physician would term “ preventive medicine,” as in the case 
of animal or human disease when we consider the species 
en masse. In the protection of forests the control of wood- 
destroying fungi therefore must be a matter of prevention 
