SOME FUNGI IN WOOD.
45
apparently it is not universally true, that spores of Merulius
lacrymans are unable to germinate on sound wood, although
they do so readily on wood which contains Coniophora cerebella.
Coniophora also produces rhizomorphs, but these differ from
those of the last two in their slenderness, and in the fact that
they become red or brown and finally nearly black in colour.
These three fungi are primarily destroyers of coniferous
timber although hardwoods are sometimes attacked: thus the
sapwood of oak is not uncommonly attacked by Merulius lacry-
mans, and even the heartwood is not immune. Cartwright and
Findlay [8] however, mention that there are several instances
of extensive damage in oak timber in this country due to Phellinus
cryptarum, Karst. Like Merulius lacrymans, Phellinus cryptarum
seems to be confined to buildings, although at present it is
unsafe to be dogmatic on this point. The fungus produces a
white stringy rot, and the wood in this condition is easily crushed.
Yellowish or reddish mats of mycelium may appear on the
surface of the wood, and from them a yellowish brown liquid is
secreted. Unlike Merulius lacrymans it appears to flourish only
under very moist conditions and fairly high temperatures, nor is
it able to produce strands and spread in the same manner. These
authors further state that decay may proceed within a beam
without becoming apparent until sporophores are produced.
Of the other dry rot fungi mentioned by Groom, Paxillus
panuoides Fr., is a not uncommon British species occasionally
found in cellars; it requires a good deal of moisture for its growth
and produces very fine, yellow rhizomorphs which darken with age.
Lenzites saepiaria (Wulf.) Fr., which does not form rhizomorphs,
is another destructive species which is said to be responsible in
North America for a quarter of the decay in railway sleepers
and telegraph poles, besides destroying a vast amount of
structural timber; it produces a cubical brown rot in both
heartwood and sapwood in coniferous timber, or sometimes,
because the spring wood is first attacked, a ring rot; seasoning-
cracks are the means by which the fungus obtains entry into
the wood. Lenzites abietina (Bull.) Fr., behaves in a similar
way, while L. betulinus (Linn.) Fr., produces a cubical brown rot
in felled and prepared hardwoods.
Apart from Paxillus and Lenzites mention may be made of
some other members of the Agaricaceae which attack wood.