7 
The Bioiogy of Polyporus Pargamenus Fries 133 
unequally, the decayed wood appearing as light-colored areas 
while the less decayed wood lying between these areas still 
retains much of the normal color of the wood and appears 
on all three sections as a delicate network of lines. This net- 
work of less decayed wood usually is rather inconspicuous 
on the surface of dry wood but stands out quite prominently 
after the surface of the wood has been moistened. Even after 
moistening it sometimes still remains somewhat obscure in 
woods that possess very broad pith-rays, such as species of 
Quercus. In the course of time the elements within the 
individual centers for the spread of the decay become more 
or less completely disintegrated, while the thin zones of wood 
remaining between the decayed areas are still but litile 
decayed. In general, excluding hemlock, all parts of the 
annual ring are equally susceptible to the attacks of the 
fungus. In hemlock, however, the decay originates in the 
soft early wood of the growth ring, the hard late wood not 
being attacked until much later. 
As the solvent action of the fungus continues to progress 
the white, decayed areas continue to enlarge. Within the 
individual decayed areas the decay progresses mainly in a 
direction parallel to that of the woody elements. In the 
course of time the woody elements in these respective areas 
are reduced rapidly both in color and hardness until they 
become more or less pith-like. This method of decomposition 
results in the formation of innumerable pockets throughout 
the wood, these pockets being separated by thin, often almost 
membranous, layers of less decayed wood. In the interme- 
diate stage of the decay numerous white strands of mycelium, 
running both longitudinally and radially through the wood, 
often can be seen with the unaided eye. The presence of 
these strands of mycelium, however, seems to be dependent 
upon the activity of the fungal hyphze within the decayed 
wood. Ly the time the decay has progressed to this point 
the wood has lost all of its original characteristics of color, 
odor, hardness, and strength, and has become a_ bleached 
mass of pithy consistency. Standing trees frequently are 
broken- off long before they become decayed to this extent. 
