150 College of Forestry 
quently are coated with a thin layer of this compound, so 
that their walls look brown and show several contour lines. 
The accumulation of this brown product signifies the first 
step in the decomposition of wood, and numerous investi- 
gations have shown that wherever there is any sign of decom- 
position this product appears immediately. Its formation 
appears to be associated with starch-containing cells, and for 
this reason it 1s most conspicuously developed in the pith- 
ray and wood parenchyma cells, these cells in the living wood 
having been largely concerned in the storage and conduction 
of food in the wood. 
In the later stages of the decay the brown decomposition 
products appear to become further changed and more resistant 
to the action of chemical reagents. In this more resistant 
condition the brown decomposition product is mostly insolu- 
ble in alkalies and apparently can be brought into solution 
only by the use of powerful oxidizing agents, such as nitric 
acid or a mixture of hydrochloric acid and potassium 
chlorate. Such powerful reagents must necessarily change 
the nature of the substance under consideration. In a pre- 
vious paper the writer (1917°) has reported the results of 
the analysis of the infiltrated substance giving rise to the 
black zones formed in wood decayed by Polyporus parga- 
menus. As much of the results as deal with the present 
problem will be included in this discussion. The subject 
for experimentation was a log of pignut hickory [Hzcoria 
glabra (Mill.) Britton] exhibiting an advanced sap-rot 
resulting from the decay caused by Polyporus pargamenus. 
The thick corky bark of the log had proved to be very resist- 
ant to decay and remained of normal hardness. The thick 
sap-wood underlying the bark was almost completely 
destroyed save for a few isolated, small resistant areas of 
wood which were surrounded by conspicuous, thick, black 
zones, due to the accumulation of decomposition products at 
this point. A number of these resistant areas of the sap- 
wood were removed and scraped free of the surrounding com- 
pletely decayed sapwood, which was of pith-like consistency 
(Plate XX VII), and used for chemical analysis. The heart- 
