of the family _Hymenomycetes_, in which the hymenium is exposed, and
is, in fact, the most noticeable feature in the family from which its
name is derived. The pileus or cap bears on its under surface
radiating plates or gills, consisting of the hymenium, over which are
thickly scattered the basidia, each surmounted by four spicules, and
on each spicule a spore. When mature, these spores fall freely upon
the ground beneath, imparting to it the general colour of the spores.
But it must be observed that the hymenium takes the form of
gill-plates in only one order of _Hymenomycetes_, namely, the
_Agaricini_; and here, as in _Cantharellus_, the hymenium is sometimes
spread over prominent veins rather than gills. Still further
divergence is manifest in the _Polyporei_, in which order the hymenium
lines the inner surface of pores or tubes, which are normally on the
under side of the pileus. Both these orders include an immense number
of species, the former more or less fleshy, the latter more or less
tough and leathery. There are still other forms and orders in this
family, as the _Hydnei_, in which the hymenium clothes the surface of
prickles or spines, and the _Auricularini_, in which the hymenium is
entirely or almost even. In the two remaining orders, there is a
still further divergence from the mushroom form. In the one called
_Clavariei_, the entire fungus is either simply cylindrical or
club-shaped, or it is very much branched and ramified. Whatever form
the fungus assumes, the hymenium covers the whole exposed surface. In
the _Tremellini_, a peculiar structure prevails, which at first seems
to agree but little with the preceding. The whole plant is gelatinous
when fresh, lobed and convolute, often brain-like, and varying in
size, according to species, from that of a pin's head to that of a
man's head. Threads and sporophores are imbedded in the gelatinous
substance,[C] so that the fertile threads are in reality not compacted
into a true hymenium. With this introduction we may state that the
technical characters of the family are thus expressed:--
_Hymenium free, mostly naked, or, if enclosed at first, soon
exposed; spores naked, mostly quaternate, on distinct spicules_ =
HYMENOMYCETES.
[Illustration: FIG. 37.--_Agaricus nudus._]
In this family some mycologists believe that fungi attain the highest
form of development of which they are capable, whilst others contend
that the fructification of the _Ascomycetes_ is more perfect, and that
some of the noblest species, such as the pileate forms, are entitled
to the first rank. The morel is a familiar example. Whatever may be
said on this point, it is incontrovertible that the noblest and most
attractive, as well as the largest, forms are classed under the
_Hymenomycetes_.
In _Gasteromycetes_, the second family, a true hymenium is also
present, but instead of being exposed it is for a long time enclosed
in an outer peridium or sac, until the spores are fully matured, or
the fungus is beginning to decay. The common puff-ball (_Lycoperdon_)
is well known, and will illustrate the principal feature of the
family. Externally there is a tough coat or peridium, which is at
first pale, but ultimately becomes brown. Internally is at first a
cream-coloured, then greenish, cellular mass, consisting of the
sinuated hymenium and young spores, which at length, and when the
spores are fully matured become brownish and dusty, the hymenium
being broken up into threads, and the spores become free. In earlier
stages, and before the hymenium is ruptured, the spores have been
found to harmonize with those of _Hymenomycetes_ in their mode of
production, since basidia are present surmounted each by four
spicules, and each spicule normally surmounted by a spore.[D] Here is,
therefore, a cellular hymenium bearing quaternary spores, but,
instead of being exposed, this hymenium is wholly enclosed within
an external sac or peridium, which is not ruptured until the
spores are fully matured, and the hymenium is resolved into
threads, together forming a pulverulent mass. It must, however, be
borne in mind, that in only some of the orders composing this
family is the hymenium thus evanescent, in others being more or less
permanent, and this has led naturally enough to the recognition of
two sub-families, in one of which the hymenium is more or less
permanent, thus following the Hymenomycetous type; and in the
other, the hymenium is evanescent, and the dusty mass of spores tends
more towards the _Coniomycetes_, this being characterized as the
coniospermous (or dusty-spored) sub-family.
The first sub-family includes, first of all, the _Hypogæi_, or
subterranean species. And here again it becomes necessary to remind
the reader that all subterranean fungi are not included in this
order, inasmuch as some, of which the truffle is an example, are
sporidiiferous, developing their sporidia in asci. To these allusion
must hereafter be made. In the _Hypogæi_, the hymenium is permanent and
convoluted, leaving numerous minute irregular cavities, in which the
spores are produced on sporophores. When specimens are very old and
decaying, the interior may become pulverulent or deliquescent. The
structure of subterranean fungi attracted the attention of Messrs.
Tulasne, and led to the production of a splendid monograph on the
subject.[E] Another order belonging to this sub-family is the
_Phalloidei_, in which the volva or peridium is ruptured whilst the
plant is still immature, and the hymenium when mature becomes
deliquescent. Not only are some members of this order most singular in
appearance, but they possess an odour so foetid as to be unapproached in
this property by any other vegetable production.[F] In this order, the
inner stratum of the investing volva is gelatinous. When still young,
and previous to the rupture of the volva, the hymenium presents sinuous
cavities in which the spores are produced on spicules, after the
manner of _Hymenomycetes_.[G] _Nidulariacei_ is a somewhat aberrant
order, presenting a peculiar structure. The peridium consists of two or
three coats, and bursts at the apex, either irregularly or in a
stellate manner, or by the separation of a little lid. Within the
cavity are contained one or more secondary receptacles, which are
either free or attached by elastic threads to the common receptacle.
Ultimately the secondary receptacles are hollow, and spores are
produced in the interior, borne on spicules.[H] The appearance in some
genera as of a little bird's-nest containing eggs has furnished the
name to the order.
The second sub-family contains the coniospermous puff-balls, and
includes two orders, in which the most readily distinguishable
feature is the cellular condition of the entire plant, in its earlier
stages, in the _Trichogastres_, and the gelatinous condition of
the early state of the _Myxogastres_. Both are ultimately resolved
internally into a dusty mass of threads and spores. In the former,
the peridium is either single or double, occasionally borne on a
stem, but usually sessile. In _Geaster_, the "starry puff-balls," the
outer peridium divides into several lobes, which fall back in a
stellate manner, and expose the inner peridium, like a ball in the
centre. In _Polysaccum_, the interior is divided into numerous
cells, filled with secondary peridia. The mode of spore-production
has already been alluded to in our remarks on _Lycoperdon_. All
the species are large, as compared with those of the following
sub-family, and one species of _Lycoperdon_ attains an enormous
size. One specimen recorded in the "Gardener's Chronicle" was
three feet four inches in circumference, and weighed nearly ten
pounds. In the _Myxogastres_, the early stage has been the subject of
much controversy. The gelatinous condition presents phenomena so
unlike anything previously recorded in plants, that one learned
professor[I] did not hesitate to propose their exclusion from the
vegetable, and recognition in the animal, kingdom as associates of
the Gregarines. When mature, the spores and threads so much resemble
those of the _Trichogastres_, and the little plants themselves are
so veritably miniature puff-balls, that the theory of their animal
nature did not meet with a ready acceptance, and is now virtually
abandoned. The characters of the family we have thus briefly reviewed
are tersely stated, as--
_Hymenium more or less permanently concealed, consisting in most cases
of closely-packed cells, of which the fertile ones bear naked spores
on distinct spicules, exposed only by the rupture or decay of the
investing coat or peridium_ = GASTEROMYCETES.
[Illustration: FIG. 38.--_Scleroderma vulgare_, Fr.]
[Illustration: FIG. 39.--_Ceuthospora phacidioides_ (Greville).]
We come now to the second section of the _Sporifera_, in which no
definite hymenium is present. And here we find also two families, in
one of which the dusty spores are the prominent feature, and hence
termed _Coniomycetes_; the other, in which the threads are most
noticeable, is _Hyphomycetes_. In the former of these, the reproductive
system seems to preponderate so much over the vegetative, that the
fungus appears to be all spores. The mycelium is often nearly
obsolete, and the short pedicels so evanescent, that a rusty or sooty
powder represents the mature fungus, infesting the green parts of
living plants. This is more especially true of one or two orders. It
will be most convenient to recognize two artificial sub-families for
the purpose of illustration, in one of which the species are developed
on living, and in the other on dead, plants. We will commence with the
latter, recognizing first those which are developed beneath the
cuticle, and then those which are superficial. Of the sub-cuticular,
two orders may be named as the representatives of this group in
Britain, these are the _Sphæronemei_, in which the spores are contained
in a more or less perfect perithecium, and the _Melanconiei_, in which
there is manifestly none. The first of these is analogous to the
_Sphæriacei_ of _Ascomycetous_ fungi, and probably consists largely of
spermogonia of known species of _Sphæria_, the relations of which have
not hitherto been traced. The spores are produced on slender threads
springing from the inner wall of the perithecium, and, when mature, are
expelled from an orifice at the apex. This is the normal condition, to
which there are some exceptions. In the _Melanconiei_, there is no
true perithecium, but the spores are produced in like manner upon a kind
of stroma or cushion formed from the mycelium, and, when mature, are
expelled through a rupture of the cuticle beneath which they are
generated, often issuing in long gelatinous tendrils. Here, again,
the majority of what were formerly regarded as distinct species have
been found, or suspected, to be forms of higher fungi. The _Torulacei_
represent the superficial fungi of this family, and these consist of a
more or less developed mycelium, which gives rise to fertile threads,
which, by constriction and division, mature into moniliform chains
of spores. The species mostly appear as blackish velvety patches or
stains on the stems of herbaceous plants and on old weathered wood.
Much interest attaches to the other sub-family of _Coniomycetes_, in which
the species are produced for the most part on living plants. So much
has been discovered during recent years of the polymorphism which
subsists amongst the species in this section, that any detailed
classification can only be regarded as provisional. Hence we shall
proceed here upon the supposition that we are dealing with autonomous
species. In the first place, we must recognize a small section in which
a kind of cellular peridium is present. This is the _Æcidiacei_, or order
of "cluster cups." The majority of species are very beautiful objects
under the microscope; the peridia are distinctly cellular, and white or
pallid, produced beneath the cuticle, through which they burst, and,
rupturing at the apex, in one genus in a stellate manner, so that the
teeth, becoming reflexed, resemble delicate fringed cups, with the
orange, golden, brown, or whitish spores or pseudospores nestling in the
interior.[J] These pseudospores are at first produced in chains, but
ultimately separate. In many cases these cups are either accompanied or
preceded by spermogonia. In two other orders there is no peridium. In the
_Cæomacei_, the pseudospores are more or less globose or ovate, sometimes
laterally compressed and simple; and in _Pucciniæi_, they are elongated,
often subfusiform and septate. In both, the pseudospores are produced
in tufts or clusters _direct from the mycelium. The Cæomacei_ might
again be subdivided into _Ustilagines_[K] and _Uredines_.[L] In the
former, the pseudospores are mostly dingy brown or blackish, and in the
latter more brightly coloured, often yellowish. The _Ustilagines_
include the smuts and bunt of corn-plants, the _Uredines_ include the
red rusts of wheat and grasses. In some of the species included in the
latter, two forms of fruit are found. In _Melampsora_, the summer
pseudospores are yellow, globose, and were formerly classed as a species
of _Lecythea_, whilst the winter pseudospores are brownish, elongated,
wedge-shaped by compression, and compact. The _Pucciniæi_[M] differ
primarily in the septate pseudospores, which in one genus (_Puccinia_) are
uniseptate; in _Triphragmium_, they are biseptate; in _Phragmidium_,
multiseptate; and in _Xenodochus_, moniliform, breaking up into
distinct articulations. It is probable that, in all of these, as is
known to be the case in most, the septate pseudospores are preceded or
accompanied by simple pseudospores, to which they are mysteriously
related. There is still another, somewhat singular, group usually
associated with the _Pucciniæi_, in which the septate pseudospores are
immersed in gelatin, so that in many features the species seem to
approach the _Tremellini_. This group includes two or three genera, the
type of which will be found in _Podisoma_.[N] These fungi are parasitic on
living junipers in Britain and North America, appearing year after year
upon the same gouty swellings of the branches, in clavate or horn-shaped
gelatinous processes of a yellowish or orange colour. Anomalous as it
may at first sight appear to include these tremelloid forms with the
dust-like fungi, their relations will on closer examination be more fully
appreciated, when the form of pseudospores, mode of germination, and
other features are taken into consideration, especially when compared with
_Podisoma Ellisii_, already alluded to. This family is technically
characterized as,--
_Distinct hymenium none. Pseudospores either solitary or concatenate,
produced on the tips of generally short threads, which are either
naked or contained in a perithecium, rarely compacted into a
gelatinous mass, at length producing minute spores_ = CONIOMYCETES.
The last family of the sporifera is _Hyphomycetes_, in which the
threads are conspicuously developed. These are what are more
commonly called "moulds," including some of the most elegant and
delicate of microscopic forms. It is true of many of these, as well
as of the _Coniomycetes_, that they are only conidial forms of
higher fungi; but there will remain a very large number of species
which, as far as present knowledge extends, must be accepted as
autonomous. In this family, we may again recognize three subdivisions,
in one of which the threads are more or less compacted into a common
stem, in another the threads are free, and in the third the threads
can scarcely be distinguished from the mycelium. It is this latter
group which unites the _Hyphomycetes_ with the _Coniomycetes_, the
affinities being increased by the great profusion with which the
spores are developed. The first group, in which the fertile threads
are united so as to form a compound stem, consists of two small
orders, the _Isariacei_ and the _Stilbacei_, in the former of which
the spores are dry, and in the latter somewhat gelatinous. Many of
the species closely imitate forms met with in the _Hymenomycetes_,
such as _Clavaria_; and, in the genus _Isaria_, it is almost beyond
doubt that the species found on dead insects, moths, spiders,
flies, ants, &c., are merely the conidiophores of species of
_Torrubia_.[O]
The second group is by far the largest, most typical, and attractive
in this family. It contains the black moulds and white moulds,
technically known as the _Dematiei_ and the _Mucedines_. In the first,
the threads are more or less corticated, that is, the stem has a
distinct investing membrane, which peels off like a bark; and the
threads, often also the spores, are dark-coloured, as if charred or
scorched. In many cases, the spores are highly developed, large,
multiseptate, and nucleate, and seldom are spores and threads
colourless or of bright tints. In the _Mucedines_, on the contrary,
the threads are never coated, seldom dingy, mostly white or of pure
colours, and the spores have less a tendency to extra development or
multiplex septation. In some genera, as in _Peronospora_ for
instance,[P] a secondary fruit is produced in the form of resting
spores from the mycelium; and these generate zoospores as well as the
primary spores, similar to those common in _Algæ_. This latter genus
is very destructive to growing plants, one species being the chief
agent in the potato disease, and another no less destructive to crops
of onions. The vine disease is produced by a species of _Oidium_,
which is also classed with _Mucedines_, but which is really the
conidiiferous form of _Erysiphe_. In other genera, the majority of
species are developed on decaying plants, so that, with the exception
of the two genera mentioned, the _Hyphomycetes_ exert a much less
baneful influence on vegetation than the _Coniomycetes_. The last
section, including the _Sepedoniei_, has been already cited as
remarkable for the suppression of the threads, which are scarcely to
be distinguished from the mycelium; the spores are profuse, nestling
on the floccose mycelium; whilst in the _Trichodermacei_, the spores
are invested by the threads, as if enclosed in a sort of false
peridium. A summary of the characters of the family may therefore be
thus briefly expressed:--
_Filamentous; fertile threads naked, for the most part free or loosely
compacted, simple or branched, bearing the spores at their apices,
rarely more closely packed, so as to form a distinct common stem_ =
HYPHOMYCETES.
[Illustration: FIG. 40.--_Rhopalomyces candidus._]
Having thus disposed of the _Sporifera_, we must advert to the two
families of _Sporidiifera_. As more closely related to the _Hyphomycetes_,
the first of these to be noticed is the _Physomycetes_, in which there
is no proper hymenium, and the threads proceeding from the mycelium bear
vesicles containing an indefinite number of sporidia. The fertile threads
are either free or only slightly felted. In the order _Antennariei_, the
threads are black and moniliform, more or less felted, bearing irregular
sporangia. A common fungus named _Zasmidium cellare_, found in cellars,
and incrusting old wine bottles, as with a blackened felt, belongs to
this order. The larger and more highly-developed order, _Mucorini_,
differs in the threads, which are simple or branched, being free, erect,
and bearing the sporangia at the tips of the thread, or branches. Some of
the species bear great external resemblance to _Mucedines_ until the
fruit is examined, when the fructifying heads, commonly globose or ovate,
are found to be delicate transparent vesicles, enclosing a large number
of minute sporidia; when mature, the sporangia burst and the sporidia
are set free. In some species, it has long been known that a sort of
conjugation takes place between opposite threads, which results in the
formation of a sporangium.[Q] None of these species are destructive to
vegetation, appearing only upon decaying, and not upon living, plants.
A state approaching putrescence seems to be essential to their vigorous
development. The following characters may be compared with those of
the family preceding it:--
_Filamentous, threads free or only slightly felted, bearing vesicles,
which contain indefinite sporidia_ = PHYSOMYCETES.
[Illustration: FIG. 41.--_Mucor caninus._]
In the last family, the _Ascomycetes_, we shall meet with a very great
variety of forms, all agreeing in producing sporidia contained in
certain cells called asci, which are produced from the hymenium. In
some of these, the asci are evanescent, but in the greater number are
permanent. In _Onygenei_, the receptacle is either club-shaped or
somewhat globose, and the peridium is filled with branched threads,
which produce asci of a very evanescent character, leaving the
pulverulent sporidia to fill the central cavity. The species are all
small, and singular for their habit of affecting animal substances,
otherwise they are of little importance. The _Perisporiacei_, on the
other hand, are very destructive of vegetation, being produced, in the
majority of cases, on the green parts of growing plants. To this order
the hop mildew, rose mildew, and pea mildew belong. The mycelium is
often very much developed, and in the case of the maple, pea, hop, and
some others, it covers the parts attacked with a thick white coating,
so that from a distance the leaves appear to have been whitewashed.
Seated on the mycelium, at the first as little orange points, are the
perithecia, which enlarge and become nearly black. In some species,
very elegant whitish appendages radiate from the sides of the
perithecia, the variations in which aid in the discrimination of
species. The perithecia contain pear-shaped asci, which spring from
the base and enclose a definite number of sporidia.[R] The asci
themselves are soon dissolved. Simultaneously with the development of
sporidia, other reproductive bodies are produced direct from the
mycelium, and in some species as many as five different kinds of
reproductive bodies have been traced. The features to be remembered in
_Perisporiacei_, as forming the basis of their classification, are,
that the asci are saccate, springing from the base of the perithecia,
and are soon absorbed. Also that the perithecia themselves are not
perforated at the apex.
The four remaining orders, though large, can be easily characterized.
In _Tuberacei_, all the species are subterranean, and the hymenium is
mostly sinuated. In _Elvellacei_, the substance is more or less
fleshy, and the hymenium is exposed. In _Phacidiacei_, the substance
is hard or leathery, and the hymenium is soon exposed. And in
_Sphæriacei_, although the substance is variable, the hymenium is
never exposed, being enclosed in perithecia with a distinct opening at
the apex, through which the mature spores escape. Each of these four
orders must be examined more in detail. The _Tuberacei_, or
subterranean _Ascomycetes_, are analogous to the _Hypogæi_ of the
_Gasteromycetes_. The truffle is a familiar and highly prized example.
There is a kind of outer peridium, and the interior consists of a
fleshy hymenium, more or less convoluted, sometimes sinuous and
confluent, so as to leave only minute elongated and irregular
cavities, and sometimes none at all, the two opposing faces of the
hymenium meeting and coalescing.[S] Certain privileged cells of the
hymenium swell, and ultimately become asci, enclosing a definite
number of sporidia. The sporidia in many cases are large, reticulated,
echinulate or verrucose, and mostly somewhat globose. In the genus
_Elaphomyces_, the asci are more than commonly diffluent.
The _Elvellacei_ are fleshy in substance, or somewhat waxy, sometimes
tremelloid. There is no peridium, but the hymenium is always exposed.
There is a great variety of forms, some being pileate, and others
cup-shaped, as there is also a great variation in size, from the
minute _Peziza_, small as a grain of sand, to the large _Helvella
gigas_, which equals in dimensions the head of a child. In the pileate
forms, the stroma is fleshy and highly developed; in the cup-shaped,
it is reduced to the external cells of the cup which enclose the
hymenium. The hymenium itself consists of elongated fertile cells, or
asci, mixed with linear thread-like barren cells, called paraphyses,
which are regarded by some authors as barren asci. These are placed
side by side in juxtaposition with the apex outwards. Each ascus
contains a definite number of sporidia, which are sometimes coloured.
When mature, the asci explode above, and the sporidia may be seen
escaping like a miniature cloud of smoke in the light of the mid-day
sun. The disc or surface of the hymenium is often brightly coloured in
the genus _Peziza_; tints of orange, red, and brown having the
predominance.
In _Phacidiacei_, the substance is hard and leathery, intermediate
between the fleshy _Elvellacei_ and the more horny of the _Sphæriacei_.
The perithecia are either orbicular or elongated, and the hymenium soon
becomes exposed. In some instances, there is a close affinity with
the _Elvellacei_, the exposed hymenium being similar in structure,
but in all the disc is at first closed. In orbicular forms, the
fissure takes place in a stellate manner from the centre, and the
teeth are reflexed. In the _Hysteriacei_, where the perithecia are
elongated, the fissure takes place throughout their length. As a
rule, the sporidia are more elongated, more commonly septate, and more
usually coloured, than in _Elvellacei_. Only a few solitary instances
occur of individual species that are parasitic on living plants.
[Illustration: FIG. 42.--_Sphæria aquila._]