ity to
them on the same host. In _AEcidium_, _Roestelia_, &c., spermogonia are
produced plentifully on or near the same spots on which the
fructification appears, either simultaneously or at a later period.[A] The
relation of _Cytispora_ to _Valsa_ was suspected by Fries very many
years ago, and, as since demonstrated, with very good reason. All
attempts, however, to establish anything like sexual reproduction in
the higher forms of _Hymenomycetes_ have at present been unsuccessful; and
the same may be said of the _Gasteromycetes_; but in _Ascomycetes_ and
_Physomycetes_ instances abound.

We know not whether any importance is to be attached to the views of
M. A. S. Oersted,[B] which have not since been confirmed, but which
have been cited with some approval by Professor de Bary, as to a trace
of sexual organs in _Hymenomycetes_. He is supposed to have seen in
_Agaricus variabilis_, P., oocysts or elongated reniform cells, which
spring up like rudimentary branches of the filaments of the mycelium,
and enclose an abundant protoplasm, if not even a nucleus. At the base
of these oocysts appear the presumed antheridia, that is to say, one
or two slender filaments, which generally turn their extremities
towards the oocysts, and which more rarely are applied to them. Then,
without ulteriorily undergoing any appreciable modifications, the
fertile cell or oocyst becomes enveloped in a network of filaments of
mycelium which proceed from the one which bears it, and this tissue
forms the rudiments of the cap. The reality of some kind of
fecundation in this circumstance, and the mode of the phenomena, if
there is one, are for the present equally uncertain. If M. Oersted's
opinion is confirmed, naturally the whole of the cap will be the
product of fecundation. Probably Karsten (Bonplandia, 1862, p. 62) saw
something similar in _Agaricus campestris_, but his account is
obscure.

[Illustration: FIG. 95.--Zygospore of _Mucor phycomyces_.]

In _Phycomyces_ the organs of reproduction have been subjected to
close examination by Van Tieghem,[C] and although he failed to
discover chlamydospores in this, he describes them in other Mucors. In
this species, besides the regular sexual development, by means of
sporangia, there is a so-called sexual reproduction by means of
zygospores, which takes place in this wise. The threads which
conjugate to form the zygospores are slender and erect on the surface
of the substratum. Two of these threads