fungus whilst still living; whilst in the case of
buried caterpillars, such as the New Zealand or British _Hepialus_, it
is difficult to decide. Whether in life or death in these instances,
it is clear that the silk-worm disease _Muscardine_ attacks the living
insect, and causes death. In the case of the _Guepes vegetantes_, the
wasp is said to fly about with the fungus partially developed.

In all fungi we may recognize a vegetative and a reproductive system:
sometimes the first only becomes developed, and then the fungus is
imperfect, and sometimes the latter is far more prominent than the
former. There is usually an agglomeration of delicate threads,
either jointed or not, which are somewhat analogous to the roots of
higher plants. These delicate threads permeate the tissues of
plants attacked by parasitic fungi, or they run over dead leaves
forming whitened patches, formerly bearing the name of _Himantia_,
but really the mycelium of some species of _Marasmius_. If checked
or disturbed, the process stops here, and only a mycelium of
interwoven threads is produced. In this condition the mycelium of one
species so much resembles that of another, that no accurate
determination can be made. If the process goes on, this mycelium gives
rise to the stem and cap of an agaricoid fungus, completing the
vegetative system. This in turn gives origin to a spore-bearing
surface, and ultimately the fruit is formed, and then the fungus is
complete; no fungus can be regarded as perfect or complete without
its reproductive system being developed. In some this is very
simple, in others it is as complex. In many of the moulds we have
miniature representatives of higher plants in the mycelium or
roots, stem, branches, and at length capsules bearing sporidia, which
correspond to seeds. It is true that leaves are absent, but these are
sometimes compensated by lateral processes or abortive branchlets.
A tuft of mould is in miniature a forest of trees. Although such a
definition may be deemed more poetic than accurate, more figurative
than literal, yet few could believe in the marvellous beauty of a
tuft of mould if they never saw it as exhibited under the microscope.
In such a condition no doubt could be entertained of its vegetable
character. But there is a lower phase in which these plants are
sometimes encountered; they may consist only of single cells, or
strings of cells, or threads of simple structure floating in
fluids. In such condi