388 
LON A. HAWKINS 
Upon pentoses and compounds of pentose sugars it has been shown 
that the amount of furfurol-yielding material in the apple is decreased 
when the apple is rotted by this fungus. This decrease is brought 
about by the action of the fungus on the compounds in the apple 
which contain pentoses. These compounds are broken down and the 
furfurol-yielding material at least is used by the fungus. In this 
process the alcohol-soluble furfurol-yielding material is increased, 
which would seem to indicate that the pentose sugars are split off 
from the compounds in which they exist in the fruit. 
The fungus is able to utilize either glucose, xylose, arabinose, 
arabin or xylan as a sole source of carbon. The three sugars are most 
efficiently utilized, xylose perhaps the best. The fungus grows better 
on xylan than on arabin. 
The filtered extract of the fungus mycelium is able to act on xylan 
under aseptic conditions with the formation of alcohol-soluble sub- 
stance which reduces Fehling's solution, forms furfurol when boiled 
with HCl and possesses other properties of xylose. This ability of 
the extract is lost on boiling. The breaking down of the xylan takes 
place gradually and the alcohol-soluble furfurol-yielding material is 
found to increase the longer the extract acts upon the xylan, the rate 
being much more rapid, however, during the early part of the action. 
A crystalline compound was obtained from the alcohol-soluble 
portion of the preparation of xylan which had been acted on by the 
extract of the fungus mycelium. This compound was apparently 
xylose. It is evident then that there is a xylanase present in the 
extract of fungus mycelium which hydrolyzes xylan to xylose. 
Office of Plant Physiological and Fermentation Investigations, 
Bureau of Plant Industry, 
U. S. Department of Agriculture 
