Sexual reproduction is oogamous with the formation of brown,
thick-walled _oospores_ which germinate after a period of rest.
Asexual reproduction by conidia and _swarmspores_. Parasites, seldom
saprophytes.
The oospores are large spores which are formed from the egg-cell
(oosphere) of the _oogonium_ (oosporangium, Fig. 89, 95). A branch of
the mycelium attaches itself to the oogonium and forms at its apex
the so-called “_antheridium_” (pollinodium[13]): this sends one or
more slender prolongations (fertilising tubes) through the wall of the
oogonium to the egg-cell.
[Illustration: FIG. 85.--_Empusa muscæ_ (Fly-mould). I. A fly
killed by the fungus, surrounded by a white layer of conidia. II.
The conidiophores (_t_) projecting from the body of the fly. Some
of the conidia, a few of which have developed secondary conidia,
are attached to the hairs (mag. 80 times). III. A perfect hypha.
IV. A hypha in the act of ejecting a conidium (_c_), enveloped
in a sticky slime (_g_). V. A conidium which has developed a
secondary conidium (_sc_). VI. A branched hypha produced by
cultivation. VII. A secondary conidium which has produced a small
mycelium (_m_). VIII. A conidium germinating on the fly’s body.
IX. Mycelium. X. Conidia germinating like yeast in the fatty
tissue of the fly. (III.-VII. and IX. magnified 300 times; VIII.
and X. magnified 500 times.)]
A fertilisation, a passage of the contents of the antheridium
to the egg-cell, has as yet only been observed in _Pythium_;
in _Phytophthora_ only one small mass of protoplasm passes
through the fertilising tube to the egg-cell; in _Peronospora_
and the Saprolegniaceæ no protoplasm can be observed to pass
through the fertilising tube, so that in these instances
_parthenogenesis_ takes place; _Saprolegnia thuretii_, etc.,
have generally even no antheridia, but nevertheless form normal
oospores. Fertilisation of the egg-cell by means of self-motile
_spermatozoids_ is only found in _Monoblepharis sphærica_.
=A.= Asexual reproduction by conidia only.