Chapter I: THE ORDINARY GERMINATION occurs by the spore emitting a germ-tube,

which immediately developes into a mycelium. In spores with a double wall it is only the inner membrane which forms the germ-tube. In swarmspores a single wall is formed after the withdrawal of the cilia, and this, by direct elongation, becomes the germ-tube. The protoplasm accumulated in the spore enters the hypha, which, in pure water, can only grow as long as the reserve nourishment lasts.

=2.= GERMINATION WITH PROMYCELIUM differs only by the circumstance that the hypha developed from the germ-tube has a very limited growth, and hence it does not immediately develope into a mycelium, but produces conidia (Rust-and Brand-Fungi). This promycelium must only be regarded as an advanced development of a conidiophore or basidium.

=3.= THE YEAST-FORMATION of conidia consists in the production of outgrowths, very much constricted at their bases, from one or more places. Each of the conidia formed in this manner may again germinate in the same way. When sufficient nourishment is present, a branched chain of such conidia is formed, and these are finally detached from one another. Yeast-like buddings from the conidia are produced in various Fungi, _e.g. Ascoidea_, _Protomyces_, Ustilagineæ, Ascomycetes, Tremellaceæ, etc. In the Ustilagineæ these conidia are an important element in the development. The budding conidia of _Exobasidium_ forms a “mould” on the nutritive solution. The yeast-like conidia are not to be confounded with the “Mucor-yeast” (comp. Mucoraceæ). For _Saccharomyces_ see Appendix to the Fungi, page 176.

In a compound spore (_i.e._ when a mass of spores are associated together) each spore germinates on its own account. There are sometimes, however, certain among them which do not germinate, but yield their contents to those which do.

The _length of time_ for which conidia can retain their power of germination is shortest (being only a few weeks) in those having thin walls and containing a large supply of water (Peronosporaceæ, Uredinaceæ). In many spores a resting period is absolutely necessary before they are able to germinate (resting spores). It has been observed in some spores and conidia, that the faculty of germinating may be preserved for several years if the conditions necessary for germination remain absent (Ustilagineæ, _Eurotium_, _Penicillium_).

The optimum, minimum and maximum temperatures required for the germination of the spores has been decided in the case of a good many Fungi. A large portion of the most common Fungi have their optimum at 20°C., minimum at 1–2°C, maximum at 40°C. In the case of pathogenic Fungi the optimum is adapted to the temperature of the blood. Fungi living in manure, whose spores are often adapted to germinate in the alimentary canals of warm-blooded animals, have an optimum corresponding to the temperature of these animals, but with a little margin.

=Systematic Division.=--The lowest class of the Fungi is that of the PHYCOMYCETES, which have an unicellular mycelium, sexual and asexual reproduction, and have doubtless sprung from sporangia-bearing, lower Green Algæ. From the Phycomycetes (and certainly from the Zygomycetes) spring two well defined branches, each with numerous distinct species; to the one branch belong the HEMIASCI and the ASCOMYCETES, to the other the HEMIBASIDII and the BASIDIOMYCETES. Ascomycetes and Basidiomycetes may be united under the title of MYCOMYCETES or HIGHER FUNGI. The Hemiasci and the Hemibasidii constitute the class of MESOMYCETES. The Hemiasci are an intermediate form between Zygomycetes and Ascomycetes; the Hemibasidii a similar group between the Zygomycetes and Basidiomycetes. Mesomycetes and Mycomycetes have only asexual reproduction; sexual reproduction is wanting. Their mycelium is multicellular.

Up to the present time about 39,000 species have been described.

Review of the divisions of the Fungi:--

Class I.--=Phycomycetes (Algal-Fungi).=

Sub-Class 1. =Zygomycetes.=
Sub-Class 2. =Oomycetes.=
Family 1. ENTOMOPHTHORALES.
Family 2. CHYTRIDIALES.
Family 3. MYCOSIPHONALES.

Class II. =Mesomycetes.=

Sub-Class 1. =Hemiasci.=
Sub-Class 2. =Hemibasidii (Brand-Fungi).=

Class III.--=Mycomycetes (Higher Fungi).=

Sub-Class 1. =Ascomycetes.=
Series 1. =Exoasci.=
Series 2. =Carpoasci.=
Family 1. GYMNOASCALES. }
Family 2. PERISPORIALES. } Angiocarpic Exoasci.
Family 3. PYRENOMYCETES. }
Family 4. HYSTERIALES. } Hemiangiocarpic Exoasci.
Family 5. DISCOMYCETES.}
Family 6. HELVELLALES. Gymnocarpic (?) Exoasci.

Additional: ASCOLICHENES. Lichen-forming Ascomycetes.

Sub-Class 2. =Basidiomycetes.=
Series 1.--Protobasidiomycetes. Partly gymnocarpic, partly
angiocarpic.
Series 2. Autobasidiomycetes.
Family 1. DACRYOMYCETES. Gymnocarpic.
Family 2. HYMENOMYCETES. Partly gymnocarpic, partly
hemiangiocarpic.
Family 3. PHALLOIDEÆ. Hemiangiocarpic.
Family 4. GASTEROMYCETES. Angiocarpic.

Additional: BASIDIOLICHENES. Lichen-forming Basidiomycetes.

Additional to the Fungi: FUNGI IMPERFECTI. Incompletely known
(_Saccharomyces_, _Oidium_-forms, etc.).

Class 1. =Phycomycetes (Algal-Fungi).=[12]

This group resembles _Vaucheria_ and the other Siphoneæ among the Algæ.

ORGANS OF NUTRITION. The mycelium is formed of a single cell, often thread-like and abundantly branched (Fig. 78). Vegetative propagation by chlamydospores and oidia. Asexual reproduction by endospores (sometimes _swarmspores_) and conidia. Sexual reproduction by conjugation of two hyphæ as in the Conjugatæ, or by fertilisation of an egg-cell in an oogonium. On this account the class of the Phycomycetes is divided into two sub-classes: ZYGOMYCETES and OOMYCETES.

Sub-Class I. =Zygomycetes.=

Sexual reproduction takes place by zygospores, which function as resting-spores, and arise in consequence of _conjugation_ (Fig. 81); in the majority of species these are rarely found, and only under special conditions. The most common method of reproduction is by endospores, by acrogenous conidia, by chlamydospores, or by oidia. _Swarmspores are wanting._ Parasites and saprophytes (order 6 and 7). The zygospores are generally produced when the formation of sporangia has ceased; _e.g._ by the suppression of the sporangial-hyphæ (_Mucor mucedo_), or by the diminution of oxygen; _Pilobolus crystallinus_ forms zygospores, when the sporangia are infected with saprophytic _Piptocephalis_ or _Pleotrachelus_.

=A.= Asexual reproduction only by sporangia.

Order 1. =Mucoraceæ.= The spherical sporangia contain many spores. The zygospore is formed between two unicellular branches (gametes).

The unicellular mycelium (Fig. 78) of the Mucoraceæ branches abundantly, and lives, generally, as a saprophyte on all sorts of dead organic remains. Some of these Fungi are known to be capable of producing _alcoholic fermentation_, in common with the Saccharomyces. This applies especially to _Chlamydomucor racemosus_ (_Mucor racemosus_), when grown in a saccharine solution, and deprived of oxygen; the mycelium, under such conditions, becomes divided by transverse walls into a large number of small cells. Many of these swell out into spherical or club-shaped cells, and when detached from one another become chlamydospores, which abstrict new cells of similar nature (Fig. 79). These chlamydospores were formerly erroneously termed “mucor-yeast,” but they must not be confounded with the yeast-conidia (page 94). They are shortened hyphæ, and are not conidia of definite size, shape, and point of budding. Oidia are also found in _Chlamydomucor_.

The Mucoraceæ, in addition to the chlamydospores and oidia, have a more normal and ordinary method of reproduction; viz., by _spores_ which are formed without any sexual act. _Mucor_ has round sporangia; from the mycelium one or more long branches, sometimes several centimetres in length, grow vertically into the air; the apex swells (Figs. 78, 80) into a sphere which soon becomes separated from its stalk by a transverse wall; in the interior of this sphere (sporangium) a number of spores are formed which eventually are set free by the rupture of the wall. The transverse wall protrudes into the sporangium and forms the well-known columella (Fig. 80 _d_, _e_). The formation of spores takes place in various ways among the different genera.

SEXUAL REPRODUCTION by conjugation takes place in the following manner. The ends of two hyphæ meet (Fig. 81) and become more or less club-shaped; the ends of each of these are cut off by a cell-wall, and two new small cells (Fig. 81 _A_) are thus formed, these coalesce and give rise to a new cell which becomes the very thick-walled zygote (zygospore), and germinates after period of rest, producing a new hypha, which bears a sporangium (Fig. 81 _E_).

_Mucor mucedo_, Pin-mould, resembles somewhat in appearance _Penicillium crustaceum_ and is found growing upon various organic materials (bread, jam, dung, etc.).

_Pilobolus_ (Figs. 83, 84) grows on manure. Its sporangium (Fig. 84 _a″_) is formed during the night and by a peculiar mechanism (page 92) is shot away from the plant in the course of the day. This generally takes place in the summer, between eight and ten a.m. The sporangium is shot away to a height which may be 300 times greater than that of the plant itself, and by its stickiness it becomes attached to portions of plants, etc., which are in the vicinity. If these are eaten by animals, the spores pass into the alimentary canal and are later on, sometimes even in a germinating condition, passed out with the excrement, in which they form new mycelia.

_Phycomyces nitens_ (“Oil-mould”) is the largest of the Mould Fungi; its sporangiophores may attain the height of 10–30 c.m.

Order 2. =Rhizopaceæ.= _Rhizopus nigricans_ (_Mucor stolonifer_) which lives on decaying fruits containing sugar, on bread, etc., has, at the base of the sporangiophores, tufts of rhizoids, _i.e._ hyphæ, which function as organs of attachment. From these, “runners” are produced which in a similar manner develope sporangiophores and rhizoids.

Order 3. =Thamnidiaceæ.= On the same sporangiophore, in addition to a large, terminal, many-spored sporangium, many smaller, lateral sporangia are formed with a few spores. Thamnidium.

=B.= Asexual reproduction by sporangia and conidia.

Order 4. =Choanephoraceæ.= _Choanephora_ with creeping endophytic mycelium, and perpendicular sporangiophores.

Order 5. =Mortierellaceæ.= _Mortierella polycephala_ produces on the same mycelium conidia and sporangiophores. _M. rostafinskii_ has a long stalked sporangiophore, which is surrounded at its base by a covering of numerous felted hyphæ.

=C.= Asexual reproduction only by conidia.

Order 6. =Chætocladiaceæ.= The conidia are abstricted singly and acrogenously. _Chætocladium_ is a parasite on the larger Mucoraceæ.

Order 7. =Piptocephalidaceæ.= The conidia are formed acrogenously and in a series, by transverse divisions. The zygospore arises at the summit of the conjugating hyphæ, which are curved so as to resemble a pair of tongs. _Piptocephalis_ and _Syncephalis_ live parasitically on the larger Mucoraceæ.

Sub-Class 2. =Oomycetes.=

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.

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.

Family 1. =Entomophthorales.=

The mycelium is richly branched. The family is a transitional step to the conidia-bearing Zygomycetes, since the oospores of many members of this family arise, and are formed, like zygospores.

Order 1. =Entomophthoraceæ.= Mycelium abundantly developed. This most frequently lives parasitically in living insects, causing their death. The conidiophores forming the conidial-layer project from the skin, and abstrict a proportionately large conidium which is ejected with considerable force, and by this means transferred to other insects. These become infected by the entrance of the germ-tube into their bodies. The spherical, brown resting-spores develope inside the bodies of insects and germinate by emitting a germ-tube.

GENERA: _Empusa_ has a good many species which are parasitic
on flies, moths, grasshoppers, plant-lice. The conidia emit a
germ-tube which pierces the skin of the insect; a number of
secondary conidia are then produced inside its body, by division
or by gemmation similar to that taking place in yeast, each
of which grows and becomes a long unbranched hypha, and these
eventually fill up the body of the animal, causing distension
and death. Each of these hyphæ projects through the skin,
and abstricts a conidium, which is ejected by a squirting
contrivance. The best known species is _E. muscæ_ (Fig. 85),
which makes its appearance epidemically towards autumn on the
common house-fly, and shows itself by the dead flies which are
found on the windows and walls attached by their probosces,
distended wings, and legs. They have swollen abdomen, broad
white belts of hyphæ between the abdominal rings, and are
surrounded by a circle of whitish dust formed by the ejected
conidia.--_Entomophthora_ sends out, at definite places, from
the mycelium hidden in the insect’s body, bundles of hyphæ,
which serve the purpose of holding fast the dead insects, the
ramifications attaching themselves to the substratum: the
conidiophores are branched, the conidia are ejected by the
divisional walls between the hyphæ and the conidia dividing into
two layers, those which terminate the hyphæ suddenly expanding
and throwing the conidia into the air. _E. radicans_ makes its
appearance epidemically on caterpillars.

=B.= Asexual reproduction by zoospores or conidia.

Family 2. =Chytridiales.=

In this family the mycelium is very sparsely developed or is wanting. The entire plant consists principally or entirely of a single zoosporangium whose zoospores have generally one cilium. The resting-spores arise either directly from the zoosporangium, which, instead of forming zoospores, surrounds itself by a thick cell-wall; or they are formed by the conjugation of two cells (in which case they are spoken of as oospores). Microscopic Fungi, parasitic on water plants (especially Algæ) or small aquatic animals, seldom on land plants.

Order 1. =Olpidiaceæ.= Without mycelium. Swarmspores and resting-spores.

In the _Olpidieæ_, the swarmspores, probably, most frequently
form themselves into a plasmodium (naked mass of protoplasm)
which may become a single zoosporangium or a resting sporangium.
_Olpidium trifolii_ occurs in _Trifolium repens_.--In the
_Synchytrieæ_ the plasmodium emerging from the swarmspores
breaks up either at once, or after a period of rest, into
smaller plasmodia, each of which will become a zoosporangium.
_Synchytrium anemones_ is found on _Anemone nemorosa_; _S.
mercurialis_ on _Mercurialis perennis_; _S. aureum_ on many
plants, particularly _Lysimachia nummularia_.

Order 2. =Rhizidiaceæ.= Mycelium present. Zoospores and resting-spores.

_Chytridium_ (Fig. 86). _Obelidium_ (Fig. 87) is bicellular; the
one cell is the mycelium, the other the zoosporangium; found
on insects. The species of _Cladochytrium_ are intercellular
parasites on marsh plants. _Physoderma._

Order 3. =Zygochytriaceæ.= Mycelium present. Zoospores and oospores. The latter are the product of the conjugation of two cells (Fig. 88).

_Polyphagus euglenæ_ on _Euglena viridis_. _Urophlyctis pulposa_
on species of _Chenopodium_.

Family 3. =Mycosiphonales.=

The mycelium is bladder-like or branched. Zoospores. Sexual reproduction by oospores, which are produced in oogonia. The latter are fertilised, in some forms, by the antheridium.

Order 1. =Ancylistaceæ.= The entire bladder-like mycelium
is used for the construction of zoosporangia, oogonia, or
antheridia. _Lagenedium_ is parasitic on _Spirogyra_, etc.

Order 2. =Peronosporaceæ.= Almost entirely _parasites_. The unicellular, often very long and abundantly branched mycelium lives in the intercellular spaces of living plants, especially in the green portions, and these are more or less destroyed and deformed in consequence. Special small branches (_suction-organs_, “_haustoria_”) are pushed into the cells in order to abstract nourishment from them. Both oospores and conidia germinate either immediately, or they develope into sporangia with swarmspores, having always two cilia. Only one oospore is formed in each oogonium; its contents (Fig. 89) divide into a centrally placed egg-cell and the “periplasm” surrounding it; this is of a paler colour and on the maturity of the oospore forms its thick, brown, external covering.

_The Potato-fungus_ (_Phytophthora infestans_) is of great interest. Its thallus winters in the Potato-tuber; other organs for passing the winter, such as oospores, are not known. When the tuber germinates, the Fungus-hyphæ penetrate the young shoot and keep pace with the aerial growth and development of the plant. The conidiophores emerge through the stomata, especially on the under side of the leaves; they branch like a tree (Fig. 90), and appear to the naked eye as a fine mould on the surface of the plant. The disease soon makes itself known by the brown colouring of those parts of the plant which are attacked, and by their withering. An ovoid conidium arises at first by the formation of a dividing wall at the apex of each branch of the conidiophore (Fig. 90 _c c_), and immediately underneath it another is formed, which pushes the first to one side, and so on. These conidia sometimes germinate directly, and form a mycelium, but most frequently their protoplasm divides into many small masses, each of which becomes a pear-shaped zoospore provided with two cilia (Fig. 91). Water is required for their germination, and when the ripe conidia are placed in a drop of water the swarm-cells are formed in the course of about five hours. They swarm about in rain and dewdrops in the Potato-fields, and are carried with the water to the Potato-plants and to the tubers in the soil. The wind also very easily conveys the conidia to healthy Potato-fields and infects them. The enormous quantity of conidia and swarm-cells that may be formed in the course of a summer explains the rapid spreading of the disease; and the preceding makes it clear why wet summers are favourable to its existence. When the swarm-cells germinate, they round off, and then surround themselves with a cell-wall which grows out into the germ-tube, and _pierces through the epidermis_ of the host-plant (Fig. 92). Having entered the host, a new mycelium is formed. The potato disease, since 1845, has been rampant in Europe; it has, no doubt, been introduced from America, which, it must be remembered, is the home of the Potato-plant.

The conidia exhibit various characters which are employed for
the separation of the genera. _Pythium_ is the most simple
form. The contents of the terminally-formed conidia emerge as
a spherical mass and divide into swarmspores. _P. de Baryanum_
lives in the seedlings of many different Flowering-plants,
which it completely destroys.--_Phytophthora_ is distinguished
by the circumstance that the sparsely-branched conidiophores
bear, sympodially, chains of conidia. Besides the Potato-fungus
(see above), _Ph. fagi_ belongs to this group; it developes
oospores very abundantly, and does great harm to seedlings of
the Beech, Sycamore, and Pine trees.--_Peronospora_ generally
has conidiophores which are repeatedly forked, and bear a
conidium on each of the most extreme ramifications. Many do
great harm to their host-plants. _P. viticola_, on Vines, and
_P. nivea_, on umbelliferous plants, have swarmspores, which are
absent in the following species of this genus: _P. sparsa_, on
Roses; _P. gangliformis_, on composites; _P. alsinearum_, on
Stitchwort; _P. parasitica_, on cruciferous plants; _P. viciæ_,
on Vetches and Peas; _P. schachtii_, on Beets; _P. violacea_,
on the flowers of _Scabiosa_; _P. radii_, on the ray-florets of
_Matricaria_.--_Cystopus_ (_Albugo_) has the conidia developed
in chains, which form a cohesive white layer underneath the
epidermis of the host-plant. _Cystopus candidus_, on cruciferous
plants, especially Shepherd’s Purse and _Brassica_; the
germination commences on the cotyledons, and from this point the
mycelium developes together with the host-plant; _C. cubicus_,
on the leaves of Compositæ.

Order 3. =Saprolegniaceæ=, _Water-Fungi_ which live as saprophytes on organic remains lying in water, for instance, on dead flies (Fig. 93), worms, remains of plants; but they may also make their appearance on living animals, being frequently found, for example, on the young trout in rearing establishments.

The thallus is a single, long and branched cell. It has one portion which serves as root, and lives in the substratum, where it ramifies abundantly for the purpose of absorbing nourishment; and another portion projecting freely in the water, and sending out hyphæ on all sides (Fig. 93). The asexual reproduction takes place by swarmspores (Fig. 94), which are developed in large sporangia; these swarmspores generally possess two cilia, and on germination grow into new plants. The entire protoplasm in the oogonium is formed into one or more oospheres, without any surrounding “periplasm.” The oospheres may not be fertilised (p. 100), and then develope parthenogenetically.

Genera: _Saprolegnia_, whose swarmspores disperse immediately
after having left the sporangium. _S. ferax_ is the
cause of a disease in fish (“Salmon disease”) and in the
crayfish.--_Achlya_, whose swarmspores accumulate in a hollow
ball before the mouth of the sporangium.--_Leptomitus_ has
strongly indented hyphæ, causing a “linked” appearance.
_L. lacteus_ is frequent in the waste matter from sugar
factories.--_Monoblepharis_ deviates from the others by the
greater development of its fertilising process; the oosphere,
situated in an open oogonium, becoming fertilised by self-motile
spermatozoids, which are provided with a cilium at the posterior
end.

Class 2. =Mesomycetes.=

The Mesomycetes are intermediate forms between the Phycomycetes and the Higher Fungi. In the vegetative organs, and in the multicellular hyphæ, they resemble the Higher Fungi; the methods of reproduction, however, show the characters of the Phycomycetes, namely sporangia and conidiophores of varying size and with varying number of spores; definite and typically formed asci and basidia are not present. Sexual reproduction is wanting. The HEMIASCI are transitional between the Phycomycetes and the Ascomycetes, the HEMIBASIDII (Brand-Fungi) form the transition to the Basidiomycetes.

Sub-Class 1. =Hemiasci.=

The Hemiasci are Fungi with _sporangia_ which, _although resembling asci_, yet have _not_, however, _a definite form and a definite number of spores_. Besides endospores, conidia, chlamydospores and oidia are found.

Order 1. =Ascoideaceæ.= _Ascoidea rubescens_ forms irregular,
reddish-brown masses in the sap issuing from felled Beeches. It
has _free sporangia_, which resemble asci in their structure, in
the development and ejection, and in the definite shape and size
of the spores. The formation of the sporangia takes place when
the nutriment is nearly exhausted, and resembles that of the
conidia, since they are developed from the end of a hypha which
enlarges, and the swelling becomes separated by a transverse
wall. Within the sporangia numerous spores of a cap-like form
are developed, which are set free through an opening at the
apex. Sporangia are formed successively at the apex of the
same hypha, the second commencing to develope as the first is
dehiscing. Conidia and sporangia are not formed simultaneously;
the former may be considered as closed sporangia.

Order 2. =Protomycetaceæ.= _Protomyces pachydermus_ causes
hard swellings on the stems and leaf-stalks of the Cichorieæ
(_Taraxacum_, etc.). These swellings consist of _chlamydospores_
(resting-spores), which germinate and become free, ascus-like
sporangia, with numerous small spores. In nutritive solutions
the chlamydospores form conidia with yeast-like buddings. _P.
macrosporus_ on _Ægopodium_, and other Umbelliferæ.

Order 3. =Thelebolaceæ.= _Thelebolus stercoreus_, is found
on the dung of deer, hares, and rabbits, and has _closed
sporangia_, which resemble asci in their shape and regular
construction, and in the ejection of spores. The covering
encloses only one sporangium, even where the sporangia arise
close together.

This order, by reason of the covering of the sporangia, forms the transition from the Hemiasci to the Carpoasci, while the two first supply an intermediate step to the Exoasci.

Sub-Class 2. =Hemibasidii, Brand-Fungi.=

The Brand-Fungi (also known as USTILAGINEÆ) are Fungi with _basidia-like conidiophores_, which, however, have not yet advanced to a definite form or number of conidia. They are true parasites, whose mycelium spreads itself in the intercellular spaces of Flowering plants. The mycelium is colourless, quickly perishable, has transverse walls at some distance from each other (Fig. 96), and sends out haustoria into the cells of the host-plant.

It most frequently happens that the germ-tube enters the host-plant at its most tender age, that is, during the germination of the seed; the mycelium then wanders about in the tissues of the shoot during its growth, until it reaches that part of the plant where the spores are to be formed. The spore-formation takes place in the same way in all those species whose brand-spores are developed in the floral parts of the host-plant. Many Brand-Fungi have, however, a more local occurrence, and the mycelium is restricted to a smaller area of the leaf or stem. Those organs of the host-plant in which the brand-spores are developed often become strongly hypertrophied. In perennial plants the mycelium winters very often in the rhizome.

The brand-spores are the winter resting-spores of the Brand-Fungi. They arise in the tissues of the host-plant, which is often destroyed, and become free through the rupture of the epidermis; they are thick-walled, generally brown or violet, and very often possess warts, spines, or reticulate markings. Fruit-bodies, that is enclosed organs of reproduction, are found in few genera (_Sphacelotheca_, _Graphiola_; _Doassansia_, Fig. 97). In _Tolyposporium_, _Tuburcinia_, _Thecaphora_ (Fig. 102), etc., the brand-spores are united into a _ball of spores_. On germination the brand-spores behave as _chlamydospores_, namely, as the fundament of conidiophores, by emitting a short germ-tube, _i.e._ a conidiophore (“promycelium”). The USTILAGINACEÆ (Fig. 99, 2) have a short _transversely divided_ conidiophore, with _laterally_ developed conidia (comp. the basidia of the Protobasidiomycetes). The conidiophores of the TILLETIACEÆ are undivided (unicellular promycelia), and bear the conidia terminally, and so resemble the basidia of the Autobasidiomycetes.

In _Tilletia_, _Entyloma_, _Neovossia_, _Tuburcinia_, the
brand-spores germinate and form basidia-like conidiophores with
spindle-shaped conidia; their mycelium, on the other hand,
produces later only single, sickle-shaped conidia, so that
two kinds of conidia are found, as in a few Basidiomycetes.
In some species, _e.g. Ustilago hordei_, the brand-spores
only germinate vegetatively and form a mycelium. In nutritive
solutions (solutions of dung, etc.) where they live as
_saprophytes_, the brand-spores of many species emit germ-tubes,
and on these, _yeast-like conidia_ are produced by repeated
budding, which grow into mycelia only when the nutritive
solution is exhausted. These conidia have not the power of
producing alcoholic fermentation. The very numerous conidia,
which are found in the dung of herbivorous animals, are probably
the yeast-conidia of Brand-Fungi. The brand-spores, which are
eaten by animals with the grain and hay, pass into the dung
and without doubt give rise to a very rich multiplication of
yeast-conidia.

The conidia (also called “sporidia”) of many species unite
generally into an H-form (Figs. 97, 4; 100 h; 101, 4). This
union in pairs does not, however, take place with a view to
germination, there is no fusion of nuclei, and therefore in this
“fusion” there is no sexual act.

Order 1. =Ustilaginaceæ.= Conidiophores with transverse walls
and lateral conidia.--_Ustilago_ (Fig. 99) generally developes
its spores in the floral organs of its host-plant, the ovary or
anthers, where they arise from hyphæ, and form a slimy mass
which when mature becomes a black dust.

To this order belong _U. avenæ_, parasitic on Oats, _U. hordei_
and _U. nuda_ (_U. jenseni_), on Barley; these are the usual
cause of “Smut” on cereals. _U. hypodytes_ on straw of _Elymus_
and _Agropyrum_. _U. filiformis_ in the leaves of _Glyceria_.
_U. caricis_ transforms the fruits of various species of
_Carex_ into black, dusty balls. _U. violacea_ developes its
violet spore-powder in the anthers of the Caryophyllaceæ.
_U. tragopogonis_, transforms entire inflorescences of
_Tragopogon_ into a black-violet mass. Among the largest are _U.
grandis_, which causes the large swollen nodes in the stem of
_Phragmites_, and the Maize Blight, _U. maydis_, which produces
outgrowths about the size of a hand on the spadix of the Maize.

Order 2. =Tilletiaceæ.= Conidiophores undivided, generally
several conidia arise at their apices.--_Tilletia tritici_,
the _Stinkbrand on Wheat_ (Fig. 100). The mycelium lives in
Wheat-plants, producing its spores in the ovary after the whole
interior of this body has been destroyed by the mycelium, with
the exception of the external layer of the wall of the ovary,
which remains essentially unaltered and encloses the closely
packed, firm mass of spores (Fig. 100 _d_). The grains of Wheat
thus attacked are shorter and thicker than the sound ones,
and the ears show the presence of this Fungus by their erect
position, and the wide separation of the chaff (Fig. 100 _a_).
The unpleasant odour of the ovary prior to the ripening of the
spores, has given the name “Stinkbrand,” and, in like manner,
its hardness when it encloses the ripe spores, is the reason
of its being also called “Stonebrand.” On account of this
hardness, the diseased grains are readily harvested together
with the healthy ones, which become infected by the spores at
the threshing. _T. lævis_ (_T. fœtens_) also occurs on Wheat and
has smooth brand-spores.

_Entyloma_ (Fig. 96), a genus with numerous species, which
appear in spots on the leaves of the host-plant, and
_Tuburcinia_ (Fig. 98), which makes its appearance on the
Primulaceæ, produce white conidia-spots on the surface of the
host-plant. The first-named has single spores, the latter has
its spores closely massed together.--_Urocystis_ (Fig. 101)
has its spores surrounded by a number of small and lighter
coloured barren spores. _U. occulta_, Rye-stem Blight, forms
its spores in long streaks in the stems and leaves of the Rye,
and does considerable damage. _U. cepulæ_ on Onions. _U. violæ_
forms large dark-violet swellings in the leaf-stalk and stems
of Violets.--_Thecaphora_ (Fig. 102) appears in seedlings of
_Convolvulus_ and _Astragalus_.

As a means of protection against the Smut-Fungi which make their
appearance on the different cereals, a submersion of the grains
in a solution of blue vitriol (½%) for twelve hours, or better
still, submerging for five minutes in water heated to 53–55° _C_
(Jensen’s method) is employed.

Class 3. =Mycomycetes, Higher Fungi.=

The MYCOMYCETES are not entirely aquatic in habit; they have hyphæ with _transverse walls_, but _no sexual reproductive organs_. The asexual reproduction takes place in very different ways; by endospores (in asci), conidia, basidiospores, chlamydospores, and oidia. Swarmspores are never found.

Two chief methods of reproduction may be distinguished, and hence the class may be divided into two large sub-classes:--the ASCOMYCETES (with asci), and the BASIDIOMYCETES (with basidia).

Sub-Class 1. =Ascomycetes.=

The main characteristic which distinguishes the Ascomycetes is the _ascus_; a name given to a sporangium of a definite shape and size, and containing a definite number of spores. The shape is generally club-like or spherical, the number of spores 8 (in some 2, 4, 16 or more), see Figs. 103, 105, 108, 110, 113, 116, 120, 121, 123, 129.

In the lowest forms, the EXOASCI, the ascus springs directly from the mycelium without the formation of a fruit-body (_i.e._ ascocarp). In the higher forms, which contain many species, the CARPOASCI, the asci are united and form ascocarps which may be more or less enclosed (angiocarpic, hemiangiocarpic, and probably gymnocarpic).

The hyphæ of the _Mycelium_ in some remain free, in others they are felted together and form thick strands or flat, cushion-like bodies (compare in particular the stromata of the Pyrenomycetes). Some species form _sclerotia_ (Figs. 116, 128).

Asexual reproduction by means of _conidia_ is known in many species as the principal means of reproduction, and the one which affords the most rapid means of distribution. The conidia may be produced on conidiophores (Fig. 109), in conidial-layers (Fig. 122), and often in conidiocarps (pycnidia, Figs. 120 _d_, _e_; 123 _a_; 124 _b._). These last occur partly as the so-called “spermogonia” (that is, pycnidia with microconidia). The conidiophores never approach the basidia.

In many species the ascospores germinate and form conidia
immediately (_Nectria cinnabarina_, _Sclerotinia_, _Taphrina_,
etc.), sometimes while they are still in the ascus and before
their ejection (_Taphrina_, Fig. 105 _a_). In many instances
the conidia by means of continued budding can, for a longer
or shorter time, produce yeast-conidia, _e.g. Taphrina_. In
many other cases the conidia arise from the germ-tubes of the
ascospores, or at any part of the mycelium. The unripe asci
of _Taphrina_, when placed in water, develop conidia at their
apices. The _Sclerotinia_-species produce numerous conidia
whose germination has never been observed. The formation of
conidia and asci sometimes takes place on the same fruit-body.
In _Heterosphæria patella_ the conidia and asci are developed
successively in the same fruit-body; in the ascocarps of
_Dermatea frangula_ and _Sclerotinia sclerotiorum_ the formation
of conidia may take place. The ascocarps frequently arise
from the conidial-layers (_Nectria cinnabarina_, etc.). This
relationship of the two forms of reproduction to each other
may be explained by considering that both have descended
phylogenetically from sporangia.

Sometimes _chlamydospores_ and _oidia_ also appear in the Ascomycetes; on germination, however, they do not, as in _Protomyces_, form sporangia, and on this account cannot be distinctly distinguished from conidia.

The asci are morphologically the highest form of reproduction and are always found at the close of the development of these Fungi; the accessory forms of reproduction are first developed, but a well-defined alternation of generations does not occur.

In the Ascomycetes there are more than 11,000 described species,
which can be classed as follows:--

Series 1. EXOASCI. Only one order.
„ 2. CARPOASCI.
Family 1. _Gymnoascales_, }
„ 2. _Perisporiales_, } Angiocarpic Carpoasci.
„ 3. _Pyrenomycetes_, }
„ 4. _Hysteriales_, } Hemiangiocarpic Carpoasci.
„ 5. _Discomycetes_,}
„ 6. _Helvellales_, Gymnocarpic (?) Carpoasci.
Additional _Ascolichenes_: Lichen-forming Ascomycetes.

Series 1. =Exoasci.=

Ascomycetes with FREE ASCI; sometimes also conidia, chlamydospores and oidia. One order.

Order. =Taphrinaceæ.= Of the genera belonging to this order, _Taphrina_, _Endomyces_, and _Ascocorticium_, the first is most important.

_Endomyces decipiens_ is a parasite in the fruit-body of
_Armillaria mellea_; _E. magnusii_ lives in the gelatinous,
fermenting exudations of Oak-trees; _Ascocorticium albidum_
is found under the bark of the Fir-tree. _Endomyces_ has
chlamydospores and oidia.

The species of _Taphrina_ are parasites, whose free asci may be found in great numbers, generally closely pressed together, on the parts of plants which they have attacked. The asci are developed directly from the ascogenous cells of a fertile, generally sub-cuticular, hypha, which arises from the sterile mycelium. The latter arises from the germinating ascospore, and may hibernate in the tissues of its host, particularly in the winter buds, and then with the commencement of the next period of vegetation it continues its growth side by side with that of its host. The hyphæ ramify in the intercellular spaces or beneath the cuticle, but have no haustoria. The ascospores (Fig. 105 _A_) and unripe asci may produce conidia.

Very remarkable appearances, and swellings of the attacked
tissues, are produced when the mycelium is perennial; for
example, the “Witches’-brooms” and “Pockets.” The hard, hollow,
stoneless plums, known as “Pocket” or “Bladder” Plums, are
produced by considerable changes in the tissues of the fruit;
these are caused particularly by _T. pruni_ on several species
of _Prunus_. The “Witches’-brooms,” on the contrary, are
deformations of entire twigs or branches, and often attain
a very large size. They occur on _Alnus incana_, caused by
_T. epiphylla_; on _Carpinus betulus_, by _T. carpini_; on
Cherry-trees, by _T. cerasi_; on Plum-trees, by _T. insititiæ_;
on Birches, by _T. turgida_ and _T. betulina_. _T. deformans_
attacks the leaves of the Peach, and causes them to curl.

When a perennial mycelium is wanting, the infection is confined
as a rule to white or yellow spots on the leaves, _e.g._ the
commonest, _T. sadebeckii_, on _Alnus glutinosa_, and _T. aurea_
on species of _Populus_. _T. alni incanæ_ (Fig. 106) causes
considerable hypertrophies on the pistillate catkins of the
Alder, which may be compared to the “pockets” of _Prunus_.

Series 2. =Carpoasci.=

The Carpoasci are Ascomycetes, whose asci are enclosed in fruit-bodies, _i.e. ascocarps_. The accessory means of reproduction are free conidiophores (Fig. 109), conidial-layers (Fig. 122), conidiocarps (Fig. 120 _D_, _E_, etc.), chlamydospores and oidia.

For the different methods of distributing the ascospores, see p. 92.

Of the six families of the Carpoasci, the first three--_Gymnoascales_, _Perisporiales_, and _Pyrenomycetes_--are ANGIOCARPIC (that is, the ascocarp remains closed throughout its existence, and does not dehisce when ripe); the fourth and fifth families (_Hysteriales_ and _Discomycetes_), on the other hand, are HEMIANGIOCARPIC (the ascocarp, here also called an _apothecium_, is closed in the early stages, but opens at the commencement of ripening and exposes a hymenium of crowded asci); the family of _Helvellales_ has probably GYMNOCARPIC (or hemiangiocarpic) fruit-bodies.

Family 1. =Gymnoascales.=

The ascocarps are surrounded by a _spongy and incomplete envelope_. One order, poor in species.

Order =Gymnoascaceæ=.--The ascocarps are borne sometimes
solitarily, or sometimes coiled together. _Gymnoascus reessii_
forms small bodies about 1 mm. in diameter on old horse-dung,
which at first are white and afterwards orange-red.--_Ctenomyces
serratus_ lives on the old feathers in birds’ nests.

Family 2. =Perisporiales.=

The ascocarps are surrounded by a _complete envelope_ without any opening: the fruit-bodies are cleistocarpic; the spores are only liberated after the disintegration of the fruit-bodies. Paraphyses are wanting. The two first orders have in addition the means of reproduction by conidia.

Order 1. =Erysiphaceæ, Mildews.= The Fungi belonging to this order are epiphytic parasites, whose mycelium, somewhat resembling a cobweb, may be seen on the leaves and other green portions of plants (see Figs. 107, 108). The hyphæ ramify in all directions upon the surface of their host, and emit haustoria which penetrate the epidermal cells, and thus derive the necessary nutriment. The Mildew-Fungi thus belong to the obligate parasites, and during their growth dwarf and destroy the portions of their host on which they live. The reproduction takes place in the first instance by abstriction of conidio-chains from the end of special branches (Fig. 108 _c_, a hypha is seen in the act of detaching a conidium). The conidia may germinate immediately, and thus quickly reproduce their species. When present in large numbers they appear as a white meal covering the surface of the plant on which the fungus is found. Later on appear the dark brown, spheroid ascocarps (Fig. 108 _a_) which, although small, are generally just visible to the naked eye as black specks.

A characteristic feature of the Mildew-Fungi is the thin, pseudo-parenchymatous covering of the ascocarp, enclosing _one_ (_Podosphæra_ and _Sphærotheca_; compare _Thelebolus_ among the Hemiasci) or _a few_ asci (Fig. 108 _c_), which do not form any hymenium, but are irregularly placed. The cells of the ascocarp-envelope are often prolonged into hair-like appendages. The ascocarps are developed from the mycelium at places where two hyphæ cross each other (Fig. 107). At these places two short and erect hyphæ are produced side by side. The one from the lower hypha (Fig. 107 _c_) assumes an ellipsoidal shape, and is known as the _archicarp_ or _ascogone_, while the other (“_pollinodium_”) arches over the ascogone. From the latter one ascus may be at once developed (_Sphærotheca_, etc.), or after its division several asci may be produced, each developed from one division. The sterile hypha (termed “pollinodium,” since it was formerly, but erroneously, supposed to fertilise the ascogone) produces a number of branches, and forms the pseudo-parenchymatous envelope of one cell in thickness, enclosing the asci.

Many plants, both cultivated and wild, are attacked by various species of Mildew. A common means of prevention against their attacks is to dust the diseased parts with sulphur.

_Sphærotheca pannosa_ occurs on the leaves of Roses, and on the
fruit of Peaches and Apricots. _S. castagnei_ on _Humulus_,
_Cucumis_, etc.--_Erysiphe tuckeri_ grows on the leaves and
fruit of the Vine; it spins its hyphæ over the bunches of
grapes, curtails their growth, and causes them to burst, and
to become decayed and rotten (Grape-disease). The Fungus was
first noticed in England in 1845, and later was found in
all countries where grapes are grown. It is only known in
the conidial form (“Oidium tuckeri”). Many other species of
_Erysiphe_ are found on herbaceous plants.--_Microsphæra_ has
appendages which are repeatedly forked at their extremities.
_M. grossulariæ_ on _Ribes grossularia_.--_Uncinula_ has
appendages with spirally-coiled extremities; on _Salix_ and
_Acer_.--_Phyllactinia_ has a circle of bristle-like appendages
with dilated bases. _P. guttata_ on _Corylus_, _Fraxinus_,
_Fagus_, etc.

Order 2. =Perisporiaceæ=, Moulds and Mildews. A group of Fungi widely distributed and found in all situations. Usually they have a well-developed surface mycelium, and small, round, seldom conspicuous ascocarps, containing ovoid, pulley-like spores. They are partly saprophytic, partly parasitic, in the latter condition having a brown mycelium.

_Eurotium glaucum_ (= _E. herbariorum_, Figs. 109, 110) and _E. repens_ live on dead organic matter, preserved fruits, etc. The conidial forms of both species are known as “Moulds” (Fig. 109), and formerly were described under the name “_Aspergillus glaucus_.” The conidia for some time remain attached to each other in chains (Fig. 109 _a_); they are abstricted from sterigmata arranged radially on the spherical, swollen end of the conidiophore. The small yellow or brownish ascocarps are frequently found in herbaria, especially when the specimens have been insufficiently dried. _Aspergillus fumigatus_ and others are pathogenic, causing mycosis in warm-blooded animals.

_Penicillium crustaceum_ (_P. glaucum_, Figs. 111, 112) is an exceedingly common “Mould.” Its mycelium appears very frequently on any organic matter which is permitted to remain untouched, and soon covers it with a dense mass of blue-green conidiophores. These branch at their summits and bear flask-shaped cells from which the conidia are abstricted. The ascocarps which, both in size and colour, resemble grains of sand, have only been obtained in luxuriant cultivation with a limited supply of oxygen.

_Capnodium salicinum_ (_Fumago salicina_, _Cladosporium
fumago_), a common Mildew, forms dark overgrowths on the leaves
and branches of various shrubs (Poplars, Elms, Willows) and on
Hops. The conidia appear in various forms, as on conidiophores,
in conidiocarps with large multicellular conidia, and in
conidiocarps with small unicellular conidia; in nutritive
solutions yeast-like conidia are also developed.--_Apiosporium
pinophilum_ produces mildew on the leaves of _Abies alba_ and
_Picea excelsa_. (The conidial-forms were formerly described as
“_Antennaria pinophila_”).

Order 3. =Tuberaceæ, Truffles.= The Fungi belonging to this order are entirely subterranean. The mycelium is filamentous, and partly parasitic upon the roots of plants, especially trees, in its neighbourhood; it is then known as _Mycorhiza_. The fruit-body is relatively large, in some cases about the size of a hen’s egg. Internally it is traversed by a number of winding passages (Fig. 113 _a_), the walls of which are coated with the asci. The asci (_b_) contain only a small number of spores, and these are set free by the putrefaction of the fruit-body. Conidia are unknown.

_Tuber melanosporum_, _T. brumale_, _T. æstivum_, and other
species are edible. _Terfezia leonis_ and _Choiromyces
mæandriformis_ are also edible. The Truffles are always found in
woods and under trees, and disappear when these are destroyed.
France and Italy produce the best and the largest number of
Truffles, which are hunted by specially trained dogs and pigs.

In _Elaphomyces_ (Stag-Truffle) the fruit-body has a corky
external layer, and is inedible. Some of the species are found
in this country. _E. granulatus_ is parasitic on the roots of
the Fir.

Family 3. =Pyrenomycetes.=

In this family the hymenium is enclosed in small fruit-bodies, _perithecia_ (Fig. 120 _b_), which appear to the naked eye as small dots. In shape they resemble a globe or a flask with a narrow mouth, through which the spores are ejected (peronocarpic ascocarps). Different kinds of reproduction--conidia, pycnidia (chiefly with microconidia), chlamydospores, and perithecia--are found in the same species. The various stages in the life-history of these Fungi are so dissimilar, that formally they were considered to be different genera. Ergot furnishes a very good example.

This family may be subdivided into 3 sub-families.

Sub-Family 1. =Hypocreales.=

The perithecia are _pale, fleshy, brightly coloured_, and generally aggregated on a stroma. Conidia and chlamydospores occur very frequently. Only one order.

Order. =Hypocreaceæ.= In this order the majority are parasites upon Flowering-plants (_Nectria_, _Polystigma_, _Epichloë_, _Claviceps_); but some are parasites upon Fungi (_Hypomyces_, _Melanospora_), or upon insects (_Cordyceps_).

The most important member of this order is the ERGOT (_Claviceps purpurea_, Figs. 114, 115, 116). This Fungus is found in the flowers of many species of Grasses, especially the Rye, attacking and destroying the ovaries. In the FIRST or CONIDIAL STAGE of the attack, the ovaries are found covered with a white, irregularly folded mycelium (Fig. 114 _m_, Fig. 115), formed of numerous hyphæ woven together and penetrating the wall of the ovary. From these a number of hyphæ (Fig. 114 _a_) project into the air and abstrict from their apices the conidia (_b_) which serve as reproductive organs. The mycelium also secretes a sticky, stinking fluid (honey-dew) in which the conidia are embedded in great numbers. The honey-dew exudes from the bases of the glumes, and is greedily sought by flies, which thus carry the conidia to other ovaries. In this manner fresh ears are infected, which might escape were the conidia only distributed by the wind. This stage formerly was regarded as an independent Fungus, known as _Sphacelia segetum_ (Fig. 115). On germination, the conidia produce either a new mycelium (Fig. 114 _d_, _c_), or new conidia. The SECOND or SCLEROTIUM STAGE is the one in which the Fungus passes the winter. The mycelium penetrates deeper and deeper into the attacked ovaries, their tissues are destroyed and replaced by the hyphæ, which gradually become more and more felted together. A firm, pseudo-parenchymatous mass of hyphæ is thus formed at the base of the loosely-woven _Sphacelia_, which is in part transformed into the hard sclerotium, and the remainder thrown off. A dark, hard, poisonous body, longer than the natural grain, is thus formed; these bodies are known as Ergots, and were formerly considered to be a distinct species,--_Sclerotium clavus_ (“Secale cornutum,” Ergot, Fig. 116 _A_, _c_). The THIRD STAGE, described as _Claviceps purpurea_, is developed in the following spring from the germinating sclerotium, which produces dark-red stromata with short stalks. In the stroma numerous perithecia with asci and ascospores are produced. The latter may infect young flowers of the cereals, in which the disease is then developed as before.

Several species of the genus _Nectria_, with blood-red
perithecia, are found as dangerous parasites, especially _N.
ditissima_, which causes “Canker” in the Beech, Ash, and Apple,
etc.; _N. cucurbitula_, which appears on Pine-trees, and _N.
cinnabarina_ (Fig. 117), whose conidial form was formerly named
_Tubercularia vulgaris_.--_Polystigma rubrum_ forms shining
red spots on the green leaves of _Prunus_-species.--_Epichloë
typhina_ is parasitic on the sheaths of Grasses, on which it
first forms a white conidial-layer, later on a yellow layer of
perithecia.--_Cordyceps_ (Chrysalis Fungus, Figs. 118, 119)
lives in and destroys insects, and after compassing their death
produces the club-formed, generally yellow, stromata, one part
of which bears conidia (_Isaria_) and another perithecia. _C.
militaris_ (Fig. 118) on the chrysalides and caterpillars of
moths, is the most common.

The so-called _Botrytis bassiana_, which produces the disease
known by the name of “Muscardine,” in silkworms, is probably a
conidial form belonging to _Cordyceps_.

Sub-Family 2. =Sphæriales.=

To this sub-family belong the majority of the Pyrenomycetes. The perithecia are of a _firm consistence_ (tough, leathery, woody or carbonaceous), and of a _dark_ colour. Their _covering_ is _quite distinct from the stroma_ when this structure is present. The stromata are sometimes very large, and may be either cushion-like, crustaceous, upright and club-like, or branched bodies. In general, small, inconspicuous Fungi, living on dead vegetable matter, sometimes parasites. Free conidiophores and conidiocarps are known in many species, and in several, chlamydospore-like forms of reproduction. Orders 3–18 constitute the Sphæriaceæ of older systematists.

Order 1. =Sordariaceæ.=--Fungi living on dung with fragile perithecia, either aerial or buried in the substratum. The dark brown or black spores have either a mucilaginous envelope (_Sordaria_, etc.) or mucilaginous appendages (_Podospora_), by means of which their expulsion and distribution are promoted.

Order 2. =Chætomiaceæ.= Perithecia fragile, free, bearing on the summit a tuft of hairs. _Chætomium_, on decaying vegetable matter.

Orders 3–7. _Perithecia scattered or aggregated, situated from the commencement on the surface of the substratum. Stroma wanting._

Order 3. =Trichosphæriaceæ.= _Trichosphæria parasitica_ (Fig. 121), on _Abies alba_; _Herpotrichia nigra_ on _Picea excelsa_ and _Pinus montana_.

Order 4. =Melanommaceæ.= _Rosellinia quercina_ lives in the roots of 1–3-year-old Oaks, and destroys the plants.

Order 5. =Ceratostomaceæ.=

Order 6. =Amphisphæriaceæ.= _Strickeria obducens_ (Fig. 120) has brick-like spores, and lives aggregated on the hard branches of _Fraxinus_.

Order 7. =Lophiostomaceæ.=

Order 8. =Cucurbitariaceæ.= Perithecia tufted, _at first embedded, then breaking through_, often situated upon an indistinct _stroma_.

Orders 9–13. _The perithecia remain embedded, and are only liberated by the casting off of the covering layers of the substratum. Stroma wanting._

Order 9. =Sphærellaceæ.= The species of _Sphærella_ have colourless, bicellular spores. They live upon the leaves of many plants, and develope spherical perithecia upon the fallen leaves.

Order 10. =Pleosporaceæ.= The conidial-forms of _Pleospora herbarum_ and _P. vulgaris_ form a black covering on various plants, known as “smuts.”--_Venturia ditricha_ occurs on the underside of dry Birch leaves, and perhaps to this belongs the conidial-form, _Fusicladium pirinum_, which causes the “Rust spots” on Apples and Pears.

Order 11. =Massariaceæ.=

Order 12. =Clypeosphæriaceæ.=

Order 13. =Gnomoniaceæ.= Perithecia, with peak-like aperture. _Gnomonia erythrostoma_ in the leaves of _Prunus avium_, which turn brown and do not fall in autumn.

Orders 14–18. _Stroma generally well developed. The perithecia are embedded in the stroma, but when this is rudimentary, in the substratum._

Order 14. =Valsaceæ.= _Valsa._

Order 15. =Diatrypaceæ.= _Diatrype._

Order 16. =Melanconidaceæ.=

Order 17. =Melogrammataceæ.=

Order 18. =Xylariaceæ.= This order is the most highly developed of the Sphæriales. The _stroma_ arises on the _surface of the substratum_, which is generally dead or decorticated wood; it is well-developed, crustaceous, hemispherical or upright. In the younger conditions it is covered with a layer of conidia, and later on it bears the _perithecia_, arranged in a layer immediately _beneath its surface_. The ascospores are of a dark colour. Often also there are free conidiophores.

_Hypoxylon_ and _Ustulina_ have a cushion-like
or crustaceous stroma.--_Xylaria_ has a club-shaped
or branched stroma, often several centimetres high. _X.
hypoxylon_ (Fig. 122) and _X. polymorpha_ occur on old
tree stumps.--_Poronia_ grows on old horse dung, and has a
conical stroma.

Sub-Family 3. =Dothideales.=

The _perithecia_ are always embedded in a _black stroma_, and are _not distinctly separated_ from it. The accessory forms of reproduction are: conidiophores, conidiocarps, and yeast-like conidia. The majority are parasites. One order.

Order =Dothideaceæ=. _Phyllachora graminis_ produces scab-like
patches on the leaves of the Grasses.--_Scirrhia rimosa_ grows
on the leaf-sheathes of _Phragmites_.--_Rhopographus pteridis_
on _Pteridium aquilinum_.

Family 4. =Hysteriales.=

This family, like the following, has hemiangiocarpic ascocarps (_apothecia_). These are closed in the early stages, but when ripe _open_ in a _valvular manner_ by a _longitudinal fissure_; they are black, oblong, and often twisted. Some species are parasites, especially upon the Coniferæ.

Order 1. =Hysteriaceæ.= _Hysterium pulicare_ upon the ruptured bark of many trees.

Order 2. =Hypodermaceæ.= The species of _Lophodermium_ live upon the leaves of Conifers, and are the cause of their falling off (_blight_). _L. pinastri_ (Fig. 125), on the leaves of _Pinus_ and _Picea_; the leaves become red-brown and fall off; at first conidiocarps are formed, and later apothecia; _L. nervisequium_ (Fig. 123), on _Abies alba_; _L. macrosporum_ (Fig. 124), on _Picea excelsa_; _L. brachysporum_, on _Pinus strobus_.

Order 3. =Dichænaceæ.=

Order 4. =Acrospermaceæ.=

Family 5. =Discomycetes.=

The ascocarps (_apothecia_) are at first closed, and _only open_ at the time of their ripening, not valvularly, but more or less like a _saucer_ or _cup_, so that the hymenium lies exposed on their upper surface. In the first three sub-families, and generally also in the fourth, the apothecia are formed inside the substratum. The apothecia are, in contrast to the Pyrenomycetes, light and brightly coloured, and their size varies very much, and may be several centimetres in diameter. Paraphyses are often present between the asci; they often contain colouring matter, and give to the disc its characteristic colour. The tissue on which the asci are borne is known as the _hypothecium_. The shape and colour of the spores is not so varied as in the Pyrenomycetes. The accessory forms of reproduction are conidia (sometimes of two forms), chlamydospores, and oidia. The family is divided into 5 sub-families.

Sub-Family 1. =Phacidiales.=

The apothecia are developed in the interior of the substratum, which they break through, and in general dehisce apically. The envelope is tough and black. Hypothecium inconspicuous; hymenium flat.

Order 1. =Euphacidiaceæ.= _Phacidium abietinum_, on the leaves
of _Abies alba_.--_Rhytisma_; the pycnidia are found in the
summer on the green leaves, while the apothecia are developed
on the fallen leaves and dehisce in the following spring. _R.
acerinum_ causes black spots on the leaves of the Sycamore, and
_R. salicinum_ on Willows.

Order 2. =Pseudophacidiaceæ.=

Sub-Family 2. =Stictidales.=

The apothecia when ripe break through the substratum which forms a border round them. Hymenium generally saucer-shaped.

Order 1. =Stictidaceæ.= _Stictis._

Order 2. =Ostropaceæ.= _Ostropa._

Sub-Family 3. =Tryblidiales.=

The apothecia are embedded in the substratum in the early stages, and then are raised high above it. Hypothecium thick. Hymenium cup-shaped.

Order 1. =Tryblidiaceæ.= _Tryblidium._

Order 2. =Heterosphæriaceæ.= _Heterosphæria patella_
on the dead stalks of Umbellifers.

Sub-Family 4. =Dermateales.=

The apothecia in the early stages are embedded in the substratum and then break through it, or are from the first situated on the surface of the substratum. Hypothecium thick.

Order 1. =Cenangiaceæ.= _Cenangium._

Order 2. =Dermateaceæ.= _Dermatea._

Order 3. =Patellariaceæ.= _Patellea_,
_Biatorella_, _Patellaria_.

Order 4. =Caliciaceæ.= _Calicium_, _Coniocybe_, etc., on the
bark of trees.

Order 5. =Arthoniaceæ.= _Arthonia_ on the bark of several trees.
_Celidium stictarum_ on the apothecia of _Sticta pulmonaria_.

Order 6. =Bulgariaceæ.= Apothecia gelatinous under moist
conditions, and horny when dried.--_Calloria fusarioides_; the
red apothecia break out in the spring on the dried stalks of
_Urtica dioica_; a gelatinous reproductive form of the Fungus is
found before the apothecia, which consists of oidia (formerly
described as “_Dacryomyces urticæ_”).--_Bulgaria inquinans_ on
the living or fallen trucks of Oaks and Beeches.

Sub-Family 5. =Pezizales.=

_The apothecia are developed on the surface of the substratum and are waxy or fleshy_; at the commencement closed, and covered with a saucer- or cup-shaped, seldom flat, hymenium. The _hypothecium_ is generally well developed. This sub-family is the richest in species of the Discomycetes and contains forms of very different habit. They grow upon dead wood, upon the ground, and upon dung. A few are parasites.

Order 1. =Helotiaceæ.= Apothecia with waxy envelope of colourless, or yellowish prosenchymatous cells.--~_Chlorosplenium æruginosum_ is found on decaying wood (particularly Oak and Birch), to which it gives a green colour. _Sclerotinia_ has sclerotia which are developed upon the host-plant and from which, after a period of rest, the long, brown-stalked apothecia arise. _S. ciborioides_ (_S. trifoliorum_, Fig. 128) is parasitic on Clover; _S. sclerotiorum_, on _Daucus_-roots, _Phaseolus_, etc.; _S. baccarum_, on the berries of _Vaccinium myrtillus_; “_Botrytis cinerea_” is a common parasite and is probably the conidial form of _S. fuckeliania_ (Fig. 127).--_Helotium herbarum_ lives on dry plant stems.--_Dasyscypha willkommii_ (Fig. 129) produces Larch-canker on the bark of the Larch.~

Order 2. =Mollisiaceæ.= _Mollisia cinerea_, principally on
decaying wood.

Order 3. =Pezizaceæ.= This order contains the largest and morphologically the highest forms of the _Discomycetes_. Apothecia fleshy, and in the later conditions generally saucer-shaped.

_Peziza_, with sessile apothecia, growing on the ground;
_P. cochleata_ is brown, and coiled like a snail-shell; _P.
coccinea_ is scarlet; _P. aurantia_ occurs as an orange-coloured
expansion on the ground.

Order 4. =Ascobolaceæ.= Apothecia fleshy; in the later stages
flat or convex. The asci are, comparatively speaking, large,
and often contain a great number of spores which escape by the
casting off of a lid on the summit of the ascus. Generally
living on dung.--_Ascobolus furfuraceus_, etc.

Family 6. =Helvellales.=

These Fungi have the appearance of clubs, bells, or mushrooms, consisting of an upright _stalk_ bearing a _large and fleshy_ head, on the _exterior surface_ of which the _hymenium_ is spread. The ascocarps are probably gymnocarpic from the beginning, and on this account these plants are placed in a separate family. The development of the ascocarps is unknown. The _Morchella_ (Morell) grows on the ground; some species are edible. 1 order.

Order. =Helvellaceæ.= _Spathulea_ is yellow and club-shaped,
and forms “fairy rings” in woods.--_Geoglossum_ (Earth-tongue)
projects above the ground as a black tongue, or as a
club-shaped body. Several species are found in meadows and
on heaths.--_Helvella_ has a stalk, bearing an irregularly
folded head, on the external surface of which is the
hypothecium.--_Morchella_ (Morell, Fig. 130), the stalk bears on
its summit the conical or spherical head, the external surface
of which is reticulate and bears the asci.--_Mitrula. Verpa._