156 College of Forestry 
a relatively small amount of humic acid as represented by 
the humic substance soluble in alkali and precipitated from 
the alkaline solution by alcohol; second, a much larger quan- 
tity of humin as represented by the great majority of the 
brown decomposition product insoluble in alkali until after 
the digestion with a mixture of hydrochloric acid and potas- 
sium chlorate, by which it was transformed into soluble 
humie acid. The solubilities and other properties of the 
respective extracts from the sound wood in which all of the 
normal carbohydrate substance was present indicate that the 
humic substance originated from boiling the carbohydrate 
substance (minus the hemicellulose, xylan) with a _Strong 
solution of hydrochloric acid and potassium chlorate.” 
As much of the results of the writer’s previous work 
(1917°) upon the black zones formed by wood-destroying 
fungi as deals with the decomposition products formed by 
Polyporus pargamenus has been summarized as follows: 
(1) The brown decomposition products formed in the 
decay of dicotyledonous woods infiltrate the cell-walls to a 
greater or less extent, frequently becoming so abundant as 
fo form numerous brown drops within the lumina of the 
cells. Such deposits appear in the wood as blackish zones 
of varying thickness which occur at first between decayed 
and undecayed areas and later separate areas in, different 
stages of decay. 
(2) The blackish zones are not constant in position since 
the decomposition products which cause the discoloration 
move forward with the advance of the decay in any part of 
the stem and ultimately disappear upon its completion within 
that part. The continual occurrence of the blackish zones 
between decayed and undecayed wood is due to the fact that 
the decomposition products are destroyed by the advancing 
fungus together with the wood while new ones are formed 
2 Tt is well known that other carbohydrates may also yield humic 
bodies. For instance sugars on boiling with a number of mineral or 
organic acids artificially yield mixtures of humic acid and humin bodies, 
varying in proportion with the different sugars used. 
