Brown : Timber Rot 
9 
boundary line about an enlarged cavity filled with isolated or 
loosely bound white fibers (Fig. 12). The wood between the 
cavities retains its original color and is, to all appearances, as 
sound as ever. In age the white contents and lining of the pockets 
may disappear and the wood presents the appearance of Figure 9.® 
In order to trace the progress of the decay in the wood, the 
following methods were employed. Diseased wood was cut into 
blocks of convenient size, which were then boiled to fix the hyphae. 
The air remaining in the tissues was exhausted with an air pump 
and the blocks were finally imbedded in celloidin in the usual man- 
ner. Sections 10 microns thin were used.® 
A microscopical examination of the wood reveals the action 
of the fungus to better advantage. In the infected areas the 
8 Another type of decay was observed in the wood near the surface of the 
logs which exhibited in the deeper-lying tissues the characteristic decay 
already described. For a distance of several millimeters inward from the 
surface, the tissue had turned dark-brownish-black. Whether this decay was 
caused by the same fungus as that in the deeper-lying tissues was not deter- 
mined. A species of Dasycypha was frequently found accompanying the 
Hymenochaete and this may have been responsible for the second type of 
decay. 
8 In preparing sections for microscopic study both temporary and per- 
manent mounts were made. The first were employed to observe through mi- 
chrochemical reactions the chemical changes in the wood brought about by 
the fungus. Among the lignin tests which were used may be enumerated the 
HCl-phloroglucin reaction, the KClOs-HCl-phenol reaction, aniline sulphate and 
H,SO,, and thallium sulphate in equal mixtures of water and alcohol . 19 The 
cellulose tests included chlor-zinc-iodide, sulphuric acid, I-KI and iodine fol- 
lowed by sulphuric acid. 
The sections used for permanent mounts were stained in several different 
ways, viz. : Delafield’s haematoxylin and aniline safranin, Haidenhain’s haema- 
toxylin and safranin, Haidenhain’s haematoxylin and methyl green, 20 per 
cent. aq. tannic acid and methyl violet, ruthenium red and methyl green. The 
last two stains enumerated gave the best results with the preference in favor 
of the methyl violet. 
In staining with methyl violet, the material was first treated with a twenty 
per cent, aqueous solution of tannic acid for twelve hours. It was then quickly 
rinsed with water and transferred directly to a one per cent, solution of 
methyl violet for three minutes. The excess stain was removed with 95 per 
cent, alcohol and the material was finally cleared in clove oil. Only the 
hyphae in the tissues retained the stain. 
The method pursued with ruthenium red and methyl violet was that 
recommended by Eisen-*. It has also been described in a recent paper by 
Learn® and does not require further explanation here because no deviations 
were made from the prescribed formula. 
