The Biology of Polyporus Pargamenus Fries 147 
and lignin constituents from the wood indicates that the 
mycelium produces diastatic, proteolytic, and a number of 
eyto-hydrolytic enzymes, among which are pectinase, cellu- 
lase, and ligninase. Aside from the histological methods 
employed i in the study of the decay of these woods, no specific 
methods were employed for the detection of enzymes.” 
The Black Zones Formed in Decaying Wood.— Undoubt- 
edly the by-products most frequently met with in decaying 
wood are the extremely chemically resistant brown humie 
products which infiltrate portions of the wood, causing them 
to appear as brownish discolored areas, or w hich more often 
collect in narrow zones between the decayed and undecayed 
portions, causing the wood at this point to appear as a black- 
ish zone or line or varying thickness. (Plate XXVII.) As 
shown by the writer (1917? ) in an earlier publication dealing 
exclusively with the study of the black zones formed by 
wood-destroying fungi,”* these formations, limiting various 
stages of the decay, are characteristic features of the early 
stages of the decay of dicotyledonous woods by wood- 
destroying fungi. These zones may extend in any direction 
through the wood or bark, their courses being determined 
by the initial starting point of the fungus and its subsequent 
growth and advancement through the wood. Their occur- 
rence may be observed best on cross sections of a tree or log 
that is but partially decayed. Here they usually appear as 
irregular black or brownish-black lines of varying thickness, 
which occur between areas of wood in different stages of 
decay, either demarking decayed from undecayed wood or 
else demarking adjacent portions of wood that are in dif- 
ferent stages of deeay. Strictly speaking, the term “ lines ” 
should not be apphed to these formations unless done in 
0 In planning the ground to be covered by the present investigation it 
was not considered advisable to lay any particular stress on the quali - 
tative and quantitative determination of enzymes, since, although of 
fundamental importance, work of this kind is of such specialized nature 
‘that it falls more nearly within the domain of the physiological chemist, 
by whom it can best be done. 2 
*t Portions of this study dealt particularly with the black zones formed 
in wood decayed by Polyporus pargamenus. 
