14 BULLETIN 871, IT. S. DEPARTMENT OF AGRICULTURE. 
STRUCTURE OF THE DISEASED WOOD. 
The structure of the decayed wood in mature pockets was found 
to be practically as described by Von Schrenk (26, p. 70-71). In the 
very early stages of decay (immature pockets), cracks in the cell walls 
such as he describes for old pockets, which were most common in the 
pits, were rather rare. It was also found that cracks often started 
from the holes in the cell walls made by the hyphae of the fungus. 
The color of the decayed wood varies from light to dark brown, de- 
pending on the state of decay. 
In some of the decayed wood examined the bordered pits gave 
much the same appearance as is often presented by starch grains in 
a plant cell which have been partially corroded by diastase. Further 
examinations showed this condition of the bordered pits to exist in 
badly decayed wood, in slightly decayed wood, in the straw-colored 
wood between the pockets, and in sound wood. Immediately upon 
treatment with xylol, and more slowly with oil of turpentine, the pits 
resumed their normal smooth appearance; consequently, the con- 
dition is the result of a deposit on the membrane of the pits, but as to 
the nature of the substance deposited or the cause of its deposition 
the writer is unable to give any information. At least, the fact that 
the deposit was found on the pits in sound wood proves that it is in 
no way a result of the action of the fungus. 
Badly decayed wood, slightly decayed wood, straw-colored and 
brownish colored wood between the pockets, and sound wood were 
treated with various reagents, the results in each case being practi- 
cally identical. Anilin sulphate colored the cell walls a brilliant 
yellow. A cherry to violet-red stain was produced by treatment 
with phloroglucin and hydrochloric acid. Chloriodid of zinc and 
alcoholic iodin with sulphuric acid both stained the walls a yellowish 
brown color. After treatment for 12 hours with Javelle water, the 
wood turned a yellowish brown upon the application of chloriodid of 
zinc, and a brilliant yellow with the addition of anilin sulphate. 
The above tests demonstrate that the lignin compounds in the cell 
walls are not changed, in so far as our present knowledge of the nature 
of so-called lignin enables us to judge. Therefore, it seems probable 
that the fungus extracts from the cell walls either the cellulose or 
some other compound yet unknown. 
THE MYCELIUM. 
Hyphas were very rare in the pockets of badly decayed wood or in 
the apparently sound wood immediately surrounding these. Proof of 
their having been quite commonly present, however, was afforded 
by the tiny holes in the cell walls of the decayed wood through which 
the hyphae had passed. In the slightly decayed wood and the wood 
