The Biology of Polyporus Pargamenus Fries 45 
a few pileate sporophores were found on adjacent parts of 
the same trunk. When the sporophores grow out from the 
lower sides of fallen stems they invariably are more or less 
resupinate. Those forming on the under sides of fallen 
stems become effused over the surface of them and develop 
into resupinate sporophores when the stems lie immediately 
upon the ground. If the lower surface of the stem 1s sup- 
ported just off the ground the sporophores tend to become 
more or less pileate in time. Those sporophores which 
develop between the immediate lower surface and the central 
peripheral portion of fallen stems are effused at first but the 
subsequent growth assumes a pileate form. 
Development of the Sporophore.— In trees having thin 
bark with numerous lenticels, such as the yellow birch, the 
mycelium invariably grows out of the lenticels. The myce- 
hum, after growing out of the lenticels as little white tufts, 
quickly develops into small nodular masses which, when no 
larger than 1/16 of an inch broad, begin to differentiate 
into little pilei each with its hymenial surface developing 
downward. The development of the pores and production 
of spores begins at this point and continues until the sporo- 
phore has attained maturity. 
In other trees having a thicker and fissured bark, such as 
the oaks or maples, the mycelium develops out of the fissures 
in the bark, frequently filling them first with a white, felty 
mass. Certain portions of this felty layer of mycelium 
develop into small nodular masses which quickly elongate 
into pilei as previously described. On trees and fallen 
trunks from which large numbers of sphorophores are devel- 
oping the whole surface frequently becomes covered with a 
felty layer of mycehum out of which new sporophores 
develop from time to time. The young sporophores are 
shallowly poroid at first but normally the pores become 
lacerate early. Occasionally mature sporophore es are found 
in which the hymenium has a perfectly poroid configuration 
even at maturity but such cases are of comparatively rare 
occurrence, 
