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The Biology of Polyporus Pargamenus Fries 151 
wood of the log, to all purposes, was sound and comparatively 
free from decay. It was evident that the fungus had sub- 
sisted upon the sapwood of the log for a period of years and 
that it had died out upon the completion of the decay of the 
sapwood. 
Radial sections (10 microns), made of peripheral portions 
of these resistant zones of wood, exhibited an abundant 
accumulation of the brown decomposition products. The 
walls of the woody elements traversed by the peripheral 
black zone were browned; the pith-ray cells contained abun- 
dant brown drops, and the lumina of many of the cells were 
occluded by accumulations of the brown decomposition 
product. Farther within the resistant zones of wood, the 
cell-walls were free from the brown coloration, but practi- 
eally all of the pith-rays contained abundant brown drops 
of humic products within their cells. All stages in the forma- 
tion of this decomposition product were present from 
recently formed droplets to those which had coalesced to 
form gum-like masses which completely occluded the cell 
lumina. (Plate XXVIII, Figs. 1 and 2.) The wood evi- 
dently was in the first stage of decay, that is, it had been 
penetrated by fungal hyphe, but its disintegration had not 
commenced. 
A series of radial sections were cut from the material 
described and employed to determine microchemically the 
solubility of these decomposition products. The solubility 
tests were made by exposing ten micron sections to the action 
of the reagent (without heating) in watch glasses, mean- 
while making observations with the microscope. If the 
numerous globules of the humic products, which were readily 
visible in the pith-ray cells under the low power of the micro- 
scope, did not dissolve after a reasonable length of time a 
small quantity of the reagent and sections were transferred 
to a test tube, heated to the boiling point, emptied out into 
a watch glass, and again examined under the microscope. 
The globules of humie products were found to be insoluble 
in water, concentrated ammonium hydroxide, 10 per cent 
solution of sodium hydroxide, 10 per cent solution of potas- 
