section of stroma; G. ascus and
paraphyses.]

It is not uncommon for the conidia of the _Sphaeria_ to partake of the
characteristics of a mould, and then the perithecia are developed
amongst the conidial threads. A recently recorded instance of this
relates to _Sphaeria Epochnii_, B. and Br.,[L] the conidia form of
which was long known before the _Sphaeria_ related to it was
discovered, under the name of _Epochnium fungorum_. The _Epochnium_
forms a thin stratum, which overruns various species of _Corticium_.
The conidia are at first uniseptate. The perithecia of the _Sphaeria_
are at first pale bottle-green, crowded in the centre of the
_Epochnium_, then black green granulated, sometimes depressed at the
summit, with a minute pore. The sporidia are strongly constricted in
the centre, at first uniseptate, with two nuclei in each division.

Another _Sphaeria_ in which the association is undoubted is the
_Sphaeria aquila_, Fr.,[M] which is almost always found nestling in a
woolly brown subiculum, for the most part composed of barren brown
jointed threads. These threads, however, produce, under favourable
conditions, mostly before the perfection of the perithecia, minute
subglobose conidia, and in this state constitute what formerly bore
the name of _Sporotrichum fuscum_, Link., but now recognized as the
conidia of _Sphaeria aquila_.

In _Sphaeria nidulans_, Schw., a North American species, we have more
than once found the dark brown subiculum bearing large triseptate
conidia, having all the characters of the genus _Helminthosporium_. In
_Sphaeria pilosa_, P., Messrs. Berkeley and Broome have observed oblong
conidia, rather irregular in outline, terminating the hairs of the
perithecium.[N] The same authors have also figured the curious
pentagonal conidia springing from flexuous threads accompanying
_Sphaeria felina_, Fckl.,[O] and also the threads resembling those of a
_Cladotrichum_ with the angular conidia of _Sphaeria cupulifera_, B.
and Br.[P] A most remarkable example is also given by the Brothers
Tulasne in _Pleospora polytricha_, in which the conidia-bearing
threads not only surround, but grow upon the perithecia, and are
crowned by fascicles of septate conidia.[Q]

Instances of this kind have now become so numerous that only a few can
be cited as examples of the rest. It is not at all improbable that the
majority of what are now classed together as species under the genus
of black moulds, _Helminthosporium_, w