i35 
Xylem of Woody Stems . 
to boiling water the power of extracting certain substances from the xylem 
which give the so-called lignin reactions, and the extractive power would 
be greatly increased under Singer’s conditions owing to the very long 
process of boiling to which his material was subjected. I have shown 
further that this delignification of the xylem may be accomplished by 
cold water. The relationship of the substance extracted by water to the 
hadromal which has been extracted by Czapek by means of a boiling 
solution of zinc chloride needs to be determined. 
Czapek (’99) has isolated a delignifying enzyme, but the details given 
of his experiment are not very complete. He employed the mycelium 
of Pleurotus pulmonarius and Merulius lacrymans | obtained from wood 
decaying under the influence of these Fungi, presumably not pure cultures. 
From these a watery extract was obtained and to the filtrate a small 
quantity of wood-filings added, together with chloroform, and incubated at 
a8°C. The alcoholic-extract, tested with phloroglucin, after three days 
showed no reaction ; after eight days a positive but weak reaction ; and 
after fourteen days the reaction was tolerably strong, while the wood 
was coloured strongly violet with chlor-zinc-iodine. 
In considering these experiments it would be useful to know from 
what tree the wood-filings were made, and again whether the wood-filings 
were examined previous to being subjected to the Fungus-extract, in 
order to determine whether any cellulose was present. The subsequent 
blue colour given by chlor-zinc-iodine cannot be accepted as evidence 
that the wood-filings had been delignified by the action of the Fungus- 
extract. Water alone extracts substances from wood which react to 
phloroglucin, and chloroform is not efficient in preventing the growth of 
Bacteria which would inevitably complicate the experiment. Positive 
evidence in favour of the hadromase is given by the fact that the Fungus- 
extract lost its wood-destroying properties when boiled, and that a white 
precipitate was thrown down by alcohol which had the same destructive 
action upon lignified cell-walls. It does not, however, afford absolute 
proof that the hadromase is a product solely of the Fungus, as, unless 
pure cultures were used under the strictest precautions to exclude Bac- 
teria, the problem is complicated by the probable development of these 
organisms, which I have shown also possess the power of destroying lignin 
compounds. 
The important papers by Marshall Ward upon the biology of Stereum 
hirsutum , and by Bififen upon the biology of Bulgaria polymorpha , which 
treat of the action of these Fungi upon the xylem, afford strong evidence 
in favour of a delignifying enzyme, these authors describing a gradually 
progressive delignifying action of the Fungus. 
In the examination of his cultures of Stereum hirsutum upon Aesculus 
wood, with the reagents for differentiating lignified membranes from those 
