y often old and decaying
individuals belonging to species of _Boletus_ will be found
filled, and their entire substance internally replaced, by the
threads and multitudinous spores of a golden yellow parasite, to
which the name of _Sepedonium chrysospermum_ has been given.
According to Tulasne, this is merely a condition of a sphaeriaceous
fungus belonging to his genus _Hypomyces_.[I]

The same observers also first demonstrated that _Trichoderma viride_,
P., was but the conidia-bearing stage of _Hypocrea rufa_, P., another
sphaeriaceous fungus. The ascigerous stroma of the latter is indeed
frequently associated in a very close manner with the cushions of the
pretended _Trichoderma_, or in other cases the same stroma will give
rise to a different apparatus of conidia, of which the principal
elements are acicular filaments, which are short, upright, and almost
simple, and which give rise to small oval conidia which are solitary
on the tips of the threads. Therefore this _Hypocrea_ will possess two
different kinds of conidia, as is the case in many species of
_Hypomyces_.

A most familiar instance of dualism will be found in _Nectria
cinnabarina_, of which the conidia form is one of the most common of
fungi, forming little reddish nodules on all kinds of dead twigs.[J]

[Illustration: FIG. 104.--Twig with _Tubercularia_ on the upper portion,
_Nectria_ on the lower.]

Almost any small currant twig which has been lying on the ground in a
damp situation will afford an opportunity of studying this phenomenon.
The whole surface of the twig will be covered from end to end with
little bright pink prominences, bursting through the bark at regular
distances, scarcely a quarter of an inch apart. Towards one end of the
twig probably the prominences will be of a deeper, richer colour, like
powdered cinnabar. The naked eye is sufficient to detect some
difference between the two kinds of pustules, and where the two merge
into each other specks of cinnabar will be visible on the pink
projections. By removing the bark it will be seen that the pink bodies
have a sort of paler stem, which spreads above into a somewhat globose
head, covered with a delicate mealy bloom. At the base it penetrates
to the inner bark, and from it the threads of mycelium branch in all
directions, confined, however, to the bark, and not entering the woody
tissues beneath. The head, placed under examination, will be found to
consist of delicate parallel threads