56 MISSOURI BOTANICAL GARDEN. 
heart wood. In general it may be said that from 45 to 60 
per cent of wood is cellulose. Besides all this, pure cul- 
tures of several of the more common of the wood rotting 
fungi have been grown upon blocks of wood, which so far 
as could be determined, had no unlignified cellulose in the 
cell walls, and delignification has resulted while similar 
control blocks have shown no such delignification. 
EFFECT OF STERILIZATION UPON WOOD BLOCKS, 
When it is considered for how long a time the thin micro- 
scopic sections of the various woods were submitted to boiling 
at extreme temperatures before any decided effect could be 
detected one can hardly say that the effect of boiling at 100 
degrees Centigrade for the time necessary for sterilization can 
be appreciable in cell walls in the interior of relatively large 
blocks of wood such as are commonly utilized for cultures 
of the wood rotting fungi. It seems that the effect upon 
the lignin of a block of wood which the investigator is sure 
has no unlignified cellulose originally, is so slight that it 
may be neglected. This is still more true when we remem- 
ber that simple soaking has a more or less solvent effect 
upon the lignin in any method of culture work. There 
can be no doubt that when finely divided wood is soaked in 
water or is boiled, lignin is extracted in sufficient quantity 
for lignin reactions to be obtained in the filtrate from the 
extracted material. But this is very different from the 
detection of that extraction by micro-chemical examina- 
tion of the treated walls themselves; for it must be con- 
fessed that micro-chemistry furnishes methods which are 
far from accurate for quantitative analysis. . 
In testing the action of fungi upon wood we must keep 
in mind the solvent action of boiling and of continual 
soaking in water and not be too hasty in drawing conclusions 
from meager results ‘which might be confused with such 
action of boiling or soaking. Control tubes of wet wood 
