46 THE ESSEX NATURALIST.
Pholiota adiposa Fr., occurs on both coniferous and broad-
leaved trees, and is described by Eades [g] as producing a brown
mottled rot in the heartwood of coniferous trees, and especially
in the silver firs. Incipient stages are marked by a yellow
coloration, and in the advanced stages the wood is yellowish with
brownish streaks, while the growth rings become separated by
masses of whitish yellow or pale brown mycelium; the tree
finally becomes hollow.
Lentinus lepideus Fr., is an extremely destructive fungus on
worked coniferous timber, especially that in contact with the
ground: it attacks railway sleepers, spreading from one to
another through the soil, and it also occurs in timbers in houses
and is common in timber yards; it produces a brown cubical
rot. It is also noted by Hubert [20] as causing a top rot,
attacking the heartwood in pines. Lentinus tigrinus (Bull.) Fr.,
is another common species, also sometimes found on hardwood
railway sleepers.
Schizophyllum commune Fr., is a rare species in this country,
but is not infrequent in tropical woods. It occurs on dead timber
and worked woods, both coniferous and broadleaved, and pro-
duces a white rot; it cannot be regarded as a serious agent of
decay. Smith [30] mentions beer casks, water butts and wood
in greenhouses as some of the habitats.
Armillaria mellea (Vahl.) Fr., is one of the commonest British
fungi, and one of the most destructive; in fact, Hiley claims
that it is by far the most destructive British toadstool and that
more trees die in Europe as a result of its activities than from
any other parasite. Numbers of broad-leaved trees are attacked,
and the fungus also occurs commonly on conifers. Hiley [18]
has described the fungus and its effect on the tree in detail, so
that only a mere outline of the story need be given here. Below
ground the fungus consists of rhizomorphs which have the
appearance of black leather bootlaces, and which consist of
compact masses of hyphae, of which the cortical ones are different
from those more centrally placed. Entry of the rhizomorphs
into the tree is through roots, and they attack the tree to a
varying height, but not very far above ground level. The
rhizomorphs lie in the cambium or just outside it, and at their
apices send out sheets of mycelium, which are white and flaky;
hyphae from this mass attack both phloem and xylem, and passing