nty with which disintegration is being carried on.
The gardener casts on one side, in a pile as rubbish, twigs and
cuttings from his trees, which are useless to him, but which have
all derived much from the soil on which they flourished. Shortly
fungi make their appearance in species almost innumerable, sending
their subtle threads of mycelium deep into the tissues of the
woody substance, and the whole mass teems with new life. In this
metamorphosis as the fungi flourish so the twigs decay, for the new
life is supported at the expense of the old, and together the
destroyers and their victims return as useful constituents to the
soil from whence they were derived, and form fresh pabulum for a
succeeding season of green leaves and sweet flowers. In woods and
forests we can even more readily appreciate the good offices of
fungi in accelerating the decay of fallen leaves and twigs which
surround the base of the parent trees. In such places Nature is left
absolutely to her own resources, and what man would accomplish in
his carefully attended gardens and shrubberies must here be done
without his aid. What we call decay is merely change; change of
form, change of relationship, change of composition; and all these
changes are effected by various combined agencies--water, air,
light, heat, these furnishing new and suitable conditions for the
development of a new race of vegetables. These, by their vigorous
growth, continue what water and oxygen, stimulated by light and
heat, had begun, and as they flourish for a brief season on the fallen
glories of the past summer, make preparation for the coming spring.

Unfortunately this destructive power of fungi over vegetable tissues
is too often exemplified in a manner which man does not approve. The
dry rot is a name which has been given to the ravages of more than one
species of fungus which flourishes at the expense of the timber it
destroys. One of these forms of dry rot fungus is _Merulius
lacrymans_, which is sometimes spoken of as if it were the only one,
though perhaps the most destructive in houses. Another is _Polyporus
hybridus_, which attacks oak-built vessels;[X] and these are not the
only ones which are capable of mischief. It appears that the dry rot
fungus acts indirectly on the wood, whose cells are saturated with its
juice, and in consequence lose their lignine and cellulose, though
their walls suffer no corrosion. The different forms of decay in wood
are accompanied