Chapter VII: Appendix: To the Ascomycetes

Family 7. =Ascolichenes (Lichen-forming Ascomycetes).=

The Lichens were formerly classed among the Thallophyta as a group quite distinct from the Algæ and Fungi. Investigations during the last twenty-five years, however, have conclusively proved that the Lichens are Fungi which reproduce in the same manner as the Ascomycetes, or, more rarely, the Basidiomycetes, and have entered into a peculiar _symbiotic relation with Algæ_, especially the Cyanophyceæ and Protococcoideæ, with which they associate, and without which they would be unable to exist. The Fungus forms the largest portion of the Lichen, enclosing the Alga with which it may be said to be commensal. The Fungus especially produces reproductive bodies and absorbs the inorganic nourishment through the rhizoids, whilst the Alga supplies it with the organic materials. In consequence of this the Lichens, in contradistinction to other Fungi, need light for the development of their nutritive organs, and are therefore, in any case internally, of a more or less greenish colour. The form and condition of the thallus is unusual among the Fungi, and they can grow upon rocks and in other places where no dead organic matter, such as would be required by other Fungi, is obtainable.

Two cellular forms are therefore to be found in each Lichen:

1. The cells which belong to the Fungus. These are generally septate, branched _hyphæ_ without any trace of chlorophyll. In the thallus of the majority of Lichens there may be found a medullary layer (Fig. 131 _m_) of loosely-woven hyphæ, between which there are large air chambers; and an _external layer_ (cortex) (Fig. 131 _o_, _u_) formed of closely-woven hyphæ without any intercellular spaces. In some Lichens (Collemaceæ) the hyphæ wind about in the thallus, being equally distributed throughout, without forming any decided strata. These Lichens moreover become gelatinous when exposed to moisture (Fig. 132), on account of the swelling of the walls of the Algæ. The hyphæ contain protoplasm with drops of oil, but never starch; their walls easily swell when exposed to damp after having been dried, and in some (_e.g._ _Cetraria islandica_) they become gelatinous when cooked. Certain strata of hyphæ become blue on treatment with iodine alone, from which it is inferred that the wall is allied, in its chemical nature, to starch.

2. The enclosed Algæ, termed “gonidia.” Some belonging to the Cyanophyceæ, Protococcoideæ, (especially _Pleurococcus_) and Chroococcaceæ, are spherical and are found isolated, or in irregular _groups_ of cells (Fig. 131 _g_); some belonging to _Nostoc_ (Fig. 132 _g_), Lyngbyaceæ, etc., are placed in cell-rows. Each Lichen, as a rule, has only one definite Algal-form for its gonidium.

The gonidia either lie together in a certain stratum between the cortex and the medullary layer (Fig. 131 _g_), or are scattered irregularly throughout the entire thallus (Fig. 132). The thallus is in the first instance termed “heteromerous,” in the second instance, “homoiomerous.” The Fungal-hyphæ embrace the gonidia and apply themselves closely to, or even penetrate them, and hence it has been difficult to decide whether the one cellular form does or does not develop from the other (Figs. 134, 135).

This theory regarding the symbiosis of Fungi and Algæ to form
a Lichen is termed the Schwendenerian theory, after the first
scientist who advanced it with any weight. It had been already
indicated by De Bary, and further arguments in its support have
at a later time been adduced by Bornet, Stahl, Treub, Frank,
Bonnier, Alfr. Möller and others.

The thallus of the Lichen appears mainly under three forms:--

1. The CRUSTACEOUS, which adheres firmly to the substratum (bark, stone) throughout its entire surface, without being raised into any free patches or lobes. It has, in many instances, no definite outline, and hyphal-branches from it often penetrate deeply into the substratum. It grows at the circumference and sometimes dies away in the centre (Figs. 138, 139, 140).

2. The FOLIACEOUS. This also lies flat upon the substratum, but is not firmly attached to and has a definite outline. It grows at the margin, and raises itself a little by free outgrowths and lobes (Fig. 141). The rhizoid-strands spring out from its whitish under surface (Fig. 131, _r_).

3. The FRUTICOSE, which is attached to its substratum at a small point from which it projects freely, either erect or pendulous. It is more or less tufted, in the form of a bush (Figs. 142, 143). These three thallus-forms gradually pass over by many intermediate forms into one another.

The Lichens, like other Ascomycetes, have very variously constructed ascospores (Fig. 137), which are enclosed in asci (Fig. 136), usually surrounded by paraphyses attached together. Furthermore they possess pycnidia (Fig. 141) containing numerous microconidia. These were formerly considered as organs of fructification, and were termed “spermatia,” and the pycnidia, “spermogonia.” Alfr. Möller proved, in 1887, that the microconidia are able to germinate and produce a mycelium with new conidia, just as in other Ascomycetes.

VEGETATIVE REPRODUCTION takes place by _soredia_, which to the naked eye appear as whitish powder on the surface of the thallus. They are small round bodies, formed by one or a group of gonidia, which are surrounded by a mass of felted hyphæ. After the rupture of the cortex they are set free, and readily carried by the wind to other places, where under favourable circumstances they establish a new thallus.

GEOGRAPHICAL DISTRIBUTION. The Lichens are the most hardy plants, and are the first to appear on hitherto bare rocks which they gradually disintegrate, and hence prepare the way for the growth of other plants. They are to be found from the Polar regions to the Equator; from the highest snow-free mountain-peaks down to the level of the sea; on the stems of trees; on rocks, soil, some even on inundated places; on stones in woodland streams, and on beaches; but they are never found upon rotten organic remains. Some grow gregariously in enormous masses, and form wide-stretching carpets, _e.g._ Reindeer Moss (_Cladonia rangiferina_), species of _Cetraria_ and other fruticose Lichens.

USES. On account of the cell-wall being composed of Lichenstarch (Lichenin), the Iceland-Lichen and Manna-Lichen (_Lecanora esculenta_) are used as food; the latter grows on stones, in the deserts of Asia and North Africa, and is often torn loose in large masses and carried away by the wind. The Reindeer-Lichen is not only the principal food of the reindeer, but it is also used in the manufacture of Danish brandy. _Cetraria islandica_ (Lichen islandicus) is OFFICINAL. Colouring materials (lacmus, orseille, persio) are made from several species, especially from _Roccella tinctoria_ (from the rocky coasts of the Mediterranean). _Parmelia saxatilis_ and particularly _Lecanora tartarea_ are used for colouring purposes in the Northern countries.

About 2,000 species of Lichens have been described. If we disregard the Basidiolichenes, which will be considered on page 176, the remaining Lichens (Ascolichenes) may be divided into the two following orders according to the structure of the fruit-bodies:--

Order 1. =Pyrenolichenes.= The ascocarps (apothecia) are spherical or flask-shaped, as in the Pyrenomycetes, more rarely linear (_Graphis_).

According to the nature of the thallus, these Lichens may be
divided into:--

_a._ Thallus homoiomerous, but not gelatinous, branching
according to the mode of growth of the Algæ: _Ephebe_ (Fig.
133), with Algæ of the genus _Stigonema_.

_b._ Thallus homoiomerous, gelatinous: _Lichina_.

_c._ Thallus heteromerous, crustaceous: _Verrucaria_,
_Pyrenula_; _Graphis_ (Fig. 139), which may be considered as
Hysteriaceæ with gonidia; several species of _Graphis_ are
common on bark.

_d._ Thallus heteromerous, foliaceous: _Endocarpon_.

_e._ Thallus heteromerous, fruticose: _Sphærophorus_.

Order 2. =Discolichenes.= These, as in the Discomycetes, have open apothecia, which, as a rule, are cupular, more rarely hemispherical (_Cladonia_).

According to the nature of the thallus, these Lichens may be
divided into:--

_a._ Thallus homoiomerous, but not gelatinous, branching
according to the mode of growth of the Algæ: _Cœnogonium_.

_b._ Thallus homoiomerous, gelatinous: _Collema_ (Fig. 132),
with Algæ of the genus _Nostoc_; _Leptogium_.

_c._ Thallus heteromerous, crustaceous: _Pertusaria_ (Fig.
140), _Lecidea_, with apothecia open from the beginning;
_Lecanora_, with apothecia, which in the beginning are closed,
later on open, but with a rim formed by the thallus (Fig. 138);
_Bæomyces_, whose apothecia are borne on a stem formed by the
thallus.

_d._ Thallus heteromerous, foliaceous: _Parmelia_ (_P.
saxatilis_; _P. parietina_, Wall-Lichen, Fig. 141, is yellow,
very frequent on tree-stems, stone-walls, tiles); _Physcia_ (_P.
ciliaris_, frequent on tree-stems); _Sticta_ (_S. pulmonacea_,
Lung-Lichen, on tree-stems); _Peltigera_, especially on the Moss
among trees; _Umbilicaria_, on rocks.

_e._ Thallus heteromerous, fruticose: _Cetraria_ (_C.
islandica_), “Iceland Moss,” with an olive-brown, flat,
furrowed, fringed thallus, on heaths; _C. nivalis_, white, in
the Polar regions; _Evernia_, _Ramalina_, _Usnea_ (_U. barbata_,
Beard-Lichen, Fig. 143); _Roccella_, _Stereocaulon_, _Cladonia_,
of which the genus _C. rangiferina_, Reindeer-Moss (Fig. 142) is
important; _Cladonia_ has two kinds of thallus, one scaly and
leaf-like, the other erect, which bears the apothecia and may be
fruticose (Fig. 142), or cupular (Fig. 144); they grow in soil
in forests and on heaths.

Sub-Class 2. =Basidiomycetes.=

This sub-class embraces the most highly developed Fungi, with large “fruit-bodies,” which in ordinary language we shortly term Funguses, Toadstools, or Mushrooms.

They have no sporangia, but reproduce only by means of basidiospores, conidia, chlamydospores and oidia. The chief characteristic of this sub-class is the _basidium_ (Fig. 145), _i.e._ the conidiophore, which has a distinctive form, and bears a definite number (generally 4) of characteristically shaped conidia (basidiospores, Fig. 145 _c_, _d_, _e_).

The summit of each basidium is produced generally into four conical points (_sterigmata_, Fig. 145 _b_), from each of which a basidiospore is abstricted. The basidia may be classified into three principal groups, each of which accompanies a distinctive conidiophore: 1, the long, filamentous, _transversely divided_ basidia, with lateral sterigmata and spores, found in the Uredinaceæ (Figs. 146 _D_, 153), Auriculariaceæ (Fig. 160 _B_), and Pilacraceæ; 2, the spherical, _longitudinally divided_ basidia of the Tremellaceæ (Figs. 160 _C d_; 161 iii. iv.); and 3, the ovoid, or cylindrical, _undivided_ basidia of the Autobasidiomycetes (Figs. 145, 163, etc.); the two last have apical sterigmata and spores.

The first two groups are the septate basidia (_protobasidia_),
of the _Protobasidiomycetes_; while the unseptate basidia
(autobasidia) of the _Autobasidiomycetes_ are the third group.
On the formation of the basidiospores, the nucleus of the
basidium divides into four nuclei, each of which is transferred
to a spore.

In addition to the basidia, _simple conidiophores_ are also found. In the Protobasidiomycetes, the simple conidia are very generally found as accessory methods of reproduction in conjunction with the basidiospores; but less frequently in the Autobasidiomycetes, _e.g._ among the Dacryomycetes, Tomentellaceæ, _Heterobasidion annosum_.

The simple conidiophores vary in size, and in the number and
shape of the conidia; they, however, resemble the basidia,
and are doubtless an early stage in the development of the
definitely formed basidia.

Finally, well-defined _chlamydospores_, formed in various ways, appear in the Basidiomycetes as supplementary reproductive bodies (compare p. 90). Among the Protobasidiomycetes, chlamydospores are at present only found among the Uredinaceæ, but in various forms; in the majority of families of the Autobasidiomycetes _oidia_ frequently occur (Fig. 162), but genuine chlamydospores seldom.

In the same species several of the known forms of reproduction may be distinguished.

The _mycelium_ is generally composed of white, branched strands, consisting of numerous felted hyphæ; in some, sclerotia are found.--The great majority are saprophytes; some (particularly all the Uredinaceæ), are parasites.

DIVISIONS OF THE BASIDIOMYCETES.

Series 1. PROTOBASIDIOMYCETES: partly gymnocarpic, partly
angiocarpic.
„ 2. AUTOBASIDIOMYCETES.
Family 1. DACRYOMYCETES: gymnocarpic.
„ 2. HYMENOMYCETES: partly gymnocarpic, partly
hemiangiocarpic.
„ 3. PHALLOIDEÆ: hemiangiocarpic.
„ 4. GASTEROMYCETES: angiocarpic.
Appended. BASIDIOLICHENES: Lichen-forming basidiomycetes.

Series I. =Protobasidiomycetes.=

To this series belong the lowest of the Basidiomycetes. The _basidia_ appear in two principal forms (1 and 2 on page 144) and are _divided_ into four cells, either transversely or longitudinally, each division forming a sterigma which abstricts a basidiospore. The first three orders, Uredinaceæ, Auriculariaceæ, and Tremellaceæ have _gymnocarpic_ fruit-bodies, while those of the Pilacraceæ, on the contrary, are _angiocarpic_.

Order 1. =Uredinaceæ (Rusts).= All the Rust-Fungi are parasites, their mycelium living in the interior of the stems and leaves of their hosts, causing red, brown, or black spots--hence their name--and malformations, sometimes of considerable size.

The Rust-Fungi are gymnocarpic and destitute of a hymenium; for these reasons they are regarded as the simplest order of the Basidiomycetes. They are entirely parasitic, and their filamentous, branched mycelium ramifies in the intercellular spaces of its host, and often protrudes haustoria into the cells. The mycelium is perennial should it enter a woody tissue; it may also hibernate in the rhizomes of perennial herbs and permeate the shoots springing from them, but in the majority of the Rust-Fungi the mycelium has a very limited growth. The chief means of reproduction of the Rust-Fungi are the _chlamydospores_, which in the more highly developed species occur in three forms, namely, the teleuto-, æcidio-, and uredo-spores. The spores, in the host, are formed immediately beneath its epidermis, which is ruptured on the ripening of the spores, with the production of “rust,” brown, red, or black spots. Those chlamydospores which produce basidia are termed _teleutospores_. The spore on germination produces a _transversely divided basidium_, “promycelium,” on which basidiospores, “sporidia,” generally four in number, are produced on lateral sterigmata. This basidio-fructification is _gymnocarpic_; the basidia neither form a hymenium nor a fruit-body (only _Cronartium_ and _Gymnosporangium_ have a slight indication of a basidio-fructification).

Many Rust-Fungi, in addition to basidiospores, have small, _unicellular conidia_, “spermatia,” which are borne in conidiocarps, “_spermogonia_.”

The ~TELEUTOSPORES~ (_Winter-spores_) may be either unicellular or multicellular; in the majority of cases they are enclosed in a hard outer cell-wall, the exospore, which in some cases is very strongly developed; they have also a long or short stalk, the remains of the spore-bearing hypha. Each cell of the teleutospore has _one germ-pore_ (a thin portion of the wall, for the protrusion of the germ-tube; in _Phragmidium_ and _Gymnosporangium_ there are, however, several germ-pores). The colour of the teleutospores is generally much darker than that of the uredospores, and it is by these that the majority of the Rust-Fungi _hibernate_.

In _Gymnosporangium_, two kinds of teleutospores are found
(distinguished by their size and thickness of exospore). In many
species of _Puccinia_, the form of the teleutospores varies
very much, so that in the same layer spores have been observed
with the characteristic form of other, allied genera.--The
teleutospores of _Endophyllum_ resemble æcidiospores, since they
are united in chains, whose cells are easily separated, and are
produced in the interior of a “peridium.” The multicellular
teleutospores of _Coleosporium_ function as basidia, and from
each cell immediately produce basidiospores.--The teleutospores
of _Coleosporium_ and _Chrysomyxa_, differ from other
teleutospores in the absence of exospore and germ-pore.

The ÆCIDOSPORES (_Spring-spores_) are produced in chains which are generally enclosed in an _envelope_ of hyphæ, the _peridium_; the _peridium_ enclosing the spores being termed the _æcidium_. The æcidiospores are unicellular, and generally of an orange colour; they are often separated by intermediate cells which wither and so assist in the distribution of the spores. The exospore is made up of minute, radially arranged rods. _Generally germination_ proceeds _immediately_, the æcidiospore producing a germ-tube, which developes into a mycelium bearing either uredo- or teleutospores.

The æcidia of many Rust-Fungi were formerly considered as
distinct genera. The æcidia of _Phragmidium_, _Triphragmium_,
and _Melampsora_, in which the _peridium is wanting_, were in
part considered as _Cæoma_. The æcidia with fimbriate edge,
or those of _Gymnosporangium_ with longitudinal lattice-like
splits, were considered as “_Rœstelia_” (Lattice-Rust); large,
sac-shaped æcidia on the Coniferæ were known as _Peridermium_.

The ~UREDOSPORES~ (_Summer-spores_) are unicellular and arise singly, seldom in chains (_Coleosporium_). Their colourless, warty exospore bears, _in the equatorial plane_, 2–8 _germ-pores_. In the majority, _germination_ proceeds _immediately_, and a mycelium is produced which at first gives rise to uredospores and afterwards to teleutospores.

The uredospore-formations of _Melampsorella_ and _Cronartium_
are enclosed in an _envelope_, and hence resemble
æcidia.--Between the uredospores sterile, unicellular hyphæ
(paraphyses) may be found.

The _spermogonia_ are spherical or pear-shaped _conidiocarps_, generally embedded in the substratum, and are produced before the æcidia, before or simultaneously with the uredospores, or before the teleutospores. The conidia, as far as observations go, do not generally germinate under ordinary conditions.

Among the Rust-Fungi some species are found which only form basidiospores and teleutospores (_Puccinia malvacearum_, _Chrysomyxa abietis_). Other species have in addition uredospores; others spermogonia and uredospores; others spermogonia and æcidia; others spermogonia, uredospores and æcidia. Those species in which all the methods of reproduction are not developed must not be considered as incomplete forms.

As a rule the mycelium, which is produced from the basidiospores, developes æcidia; in the species, however, without æcidia, it developes the uredo-form, and when the uredospores are also absent, the teleutospore-form. It has been established in some species of _Puccinia_ and _Uromyces_ that the formation of æcidia can be suppressed, and it is not a necessary part of the cycle of development of the species.

The majority of Rust-Fungi hibernate in the teleutospore-form.
Many species are able to hibernate in the uredospore-form
(_Coleosporium senecionis_). Others pass the winter in the
æcidio-form, and develope æcidia on new hosts (_Uromyces pisi_,
on _Euphorbia cyparissias_; _Phragmidium subcorticium_, on
_Rosa_; _Æcidium elatinum_, on _Abies alba_). In _Chrysomyxa
abietis_, the mycelium, developed from the basidiospores,
survives the winter.

Among the Rust-Fungi, with several forms of reproduction, there are about sixty whose development can only be completed by an _alternation of hosts_, that is, on one host only uredo-and teleutospores are produced, while the further development of the germinating basidiospores, and the formation of the æcidia and spermogonia from its mycelium, can only take place on a second quite distinct and definite host (_heterœcious_ or _metoxenous_ Fungi). Those Fungi which have all their forms of reproduction on the same host are termed _autœcious_ or _autoxenous_. It is not, however, always necessary that the heterœcious Rust-Fungi should regularly change their hosts; for example, _Puccinia graminis_ can hibernate in the uredo-form on the wild Grasses, and in the spring can distribute itself again in the same form.

As a consequence of the alternation of hosts the various forms
of development were considered as independent genera (_Uredo_,
_Æcidium_, _Rœstelia_, _Cæoma_, _Peridermium_), until De Bary
and Oersted established, about the same time (1865), the mutual
connection of some forms, and paved the way for the right
conception of these Fungi.

As an example of one of the most highly developed species, _Puccinia graminis_, the “Rust of Wheat,” holds a prominent position. Its uredospores and teleutospores are produced (Fig. 146) on Grasses (on cereals, especially Wheat, Rye, Oats, and many wild Grasses), while the æcidia and spermogonia are confined to the Berberidaceæ. The teleutospores, developed on the Grasses, hibernate on the dried portions of their host, and in the succeeding year each of the two cells of the teleutospore may develop a _basidium_ with four basidiospores (Fig. 146 _D_, _c_). The basidiospores are distributed by the wind, germinate quickly, and only proceed to further development on _Berberis_ or _Mahonia_. The germ-tube _bores through the epidermis_ of the Barberry-leaf, and forms a mycelium in its interior, its presence being indicated by reddish-yellow spots on the leaf. After 6–10 days the flask-shaped _spermogonia_ appear (Fig. 147 _B_; _C_, _a_; conidia in Fig. 147 _D_) and a few days later the cup-shaped _æcidia_ (Fig. 147 _A_; _C_, _c_, _d_, _e_). The former are generally on the _upper_, and the latter on the _under side_ of the leaf. The orange-coloured æcidiospores scatter like dust, and germinate only on Grasses; the germination takes place in about two days when placed on any green part of a Grass. The germ-tube enters the Grass-leaf through a stoma; a mycelium is developed in the leaf, giving rise to a small, oval, rust-coloured spot (Fig. 146 _A_); in about 6–9 days the epidermis is ruptured over the red spot, and numerous reddish-yellow _uredospores_, formed on the mycelium, are set free. The uredospores (Fig. 146 _B_) are scattered by the wind, and can germinate should they fall on the green portions of other Grasses: they then emit 2–4 germ-tubes through the equatorially-placed germ-pores. The germ-tubes enter a leaf through a stoma, a new mycelium is then developed, and in about eight days a fresh production of uredospores takes place, which germinate as before. The uredospore-mycelium very soon produces, in addition, the brown _teleutospores_, which give a brown colour to the rust-coloured spots, the familiar uredospores on the cereals being quite suppressed towards the close of the summer (Fig. 146 _C, D_). The “Rust of Wheat” hibernates on some wild Grasses in the uredospore-form.

GENERA. _Puccinia_ (Fig. 146, 147) has bicellular teleutospores,
each having a germ-pore, and the æcidia when present have an
indented peridium; some species, as exceptions, have 1–3-celled
teleutospores. Many species are HETERŒCIOUS, for example, _P.
graminis_, described above; _P. rubigo_, which also infests
various Grasses, but whose æcidia appear on _Anchusa_; the
masses of teleutospores are small; they contain paraphyses, and
are for a long time covered by the epidermis. _P. coronata_, on
Oats and Rye Grass; its æcidia on _Rhamnus_; the teleutospores
are surmounted by a crown--“coronate processes.” _P.
phragmitis_, on Reeds; æcidia on species of _Rumex_ and _Rheum_.
_P. moliniæ_, on _Molinia cœrulea_; the æcidia on Orchids.
_P. poarum_, on Meadow-Grass; æcidia on _Tussilago_. Various
Puccinias growing on species of _Carex_ have their æcidia on
_Urtica_, _Lysimachia_, _Cirsium_, _Pedicularis_, etc.--Of
those AUTŒCIOUS species, which have all their generations on the
same host, may be noted:--_P. galii_, _P. menthæ_, _P. violæ_,
_P. epilobii_, _P. asparagi_, which grow on the hosts from
which they have taken their specific names.--As representative
of a group which have spermogonia, uredo-and teleutospores on
the same host, but on different individuals, _P. suaveolens_,
on the Field-Thistle, may be mentioned. The spermogonia have
a strong odour.--A peculiar group (_Leptopuccinia_) has only
teleutospores, which germinate immediately, and whilst still
attached to their living host. To this group belong _P.
arenariæ_, on a number of Caryophyllaceæ; and _P. malvacearum_,
on various Malvaceæ, introduced in 1873 from South America to
Europe, where it soon proved very destructive to Hollyhocks.

_Uromyces_ (Fig. 149) differs only from _Puccinia_ in always
having unicellular teleutospores. Among this genus both
heterœcious and autœcious species are found. To the first
group belong _U. pisi_, whose æcidia are found on _Euphorbia
cyparissias_, and _U. dactylidis_, whose æcidia appear on
_Ranunculus_; to the second group belong _U. betæ_, _U.
phaseoli_, _U. trifolii_.

_Triphragmium_ has teleutospores with three cells (one below and
two above), on _Spiræa ulmaria_.

_Phragmidium_ (Fig. 150) has teleutospores consisting of a
row of cells (3–10) arranged in a straight line; the upper
cell has one germ-pore and the others four germ-pores placed
equatorially. Both this and the preceding genus have large,
irregular æcidia without peridia, but often with bent, club-like
paraphyses (150 _b_ and _c_); they are all autœcious, and are
only found on the Rosaceæ.

_Endophyllum_ (see above, under teleutospores, p. 147) on
species of _Sempervivum_.

_Gymnosporangium_ (Figs. 152, 154) has bicellular teleutospores
collected in large, gelatinous masses formed by the swelling of
the long spore-stalks; in each cell 2–4 germ-pores are found.
Uredospores are wanting. All the species are heterœcious; the
teleutospores appear on _Juniperus_, the æcidia (_Rœstelia_)
on the Pomaceæ. _G. sabinæ_, on _Juniperus sabina_, _J.
virginiana_, etc., has the æcidia (“_Rœstelia cancellata_”)
on _Pyrus communis_ (Figs. 152, 148); _G. juniperinum_, on
_Juniperus communis_ with “_Rœstelia cornuta_” (Fig. 154 _a_)
on _Sorbus aucuparia_, _Aria nivea_ (_S. aria_) and _Malus
communis_; _G. clavariæforme_ on _Juniperus communis_, the
æcidium belonging to it (“_Rœstelia lacerata_”) on _Cratægus
oxyacantha_.

_Melampsora_ has prismatic teleutospores placed parallel to each
other and forming a crustaceous layer; in many species they
are divided longitudinally into several cells (Fig. 151). The
æcidia, without peridium, belonged to the old genus _Cæoma_.
_M. caprearum_, on Willows, has the æcidia (_Cæoma euonymi_) on
_Euonymus_. _M. hartigii_, on Osiers; the æcidium on _Ribes_.
_M. mixta_, on _Salix repens_ and Orchids. _M. pinitorqua_,
on leaves of the Aspen, æcidia on Pine branches (Pine shoot
fungus); _M. populina_ on _Populus monilifera_ and _nigra_; _M.
betulina_ (Fig. 153), on Birch leaves; _M. padi_ (Fig. 151),
on leaves of _Prunus padus_, developes teleutospores in the
epidermal cells; _M. lini_ is the cause of injury to the Flax;
_M. agrimoniæ_.

_Calyptospora gœppertiana_; teleutospores on _Vaccinium vitis
idæa_; spermogonia and æcidia on _Abies alba_ (Firneedle-Rust).

_Coleosporium_ (Fig. 155) forms its uredospores in
reddish-yellow chains; for the teleutospores, see page 147.
_C. senecionis_, on the Groundsel; its æcidium (_Peridermium
wolffii_) on Pine-leaves (Fig. 155 a). Other species on
_Sonchus_, _Petasites_, _Campanula_, _Rhinanthaceæ_.

_Chrysomyxa_ (Fig. 156) has bright red, branched
teleutospore-chains; each spore developes a 4-celled basidium.
_C. ledi_, on _Ledum palustre_; its æcidia on the leaves of the
Fir. _C. abietis_ (Fig. 156), without uredo-and æcidiospores;
teleutospores on the leaves of the Fir. In the first summer,
yellow bands are formed on the leaves, and in the following
spring the red cushions of spores.

_Cronartium_ (Figs. 157, 159) has unicellular teleutospores
united in numbers to form erect threads or columns; the
uredospores are enclosed in a “peridium”; _C. ribicola_ (Fig.
157), on leaves of Ribes (especially Black Currants); its
æcidia (_Peridermium strobi_, or _P. klebahni_) on the stems
and branches of _Pinus strobus_ (Fig. 159), on which it causes
great damage; _C. asclepiadeum_, on _Vincetoxicum officinale_;
its æcidia (_Peridermium cornui_) on the stems and branches of
_Pinus silvestris_.

To the Fungi of which the æcidium is known, whilst the remaining
forms are still undetermined, but which are without doubt
heterœcious, belong _Æcidium elatinum_, which produces the
enormous “witches’ brooms” and barrel-shaped swellings on stems
and branches of _Abies alba_; and _Æcidium strobilinum_ (Fig.
158), which attacks Fir-cones, causing all the scales to become
covered with clusters of æcidia opening by a lid. _Hemileia
vastatrix_ destroyed the coffee plantations in Asia.

Order 2. =Auriculariaceæ.= The _long, transversely divided_ basidia bear laterally 4 _long sterigmata_ with basidiospores (Fig. 160 _B_) and are united to form an _hymenium_ on the surface of the fruit-body. Parasites or saprophytes.

_Auricularia sambucina_ (_Auricula judæ_), Judas’-ear, has large
fruit-bodies, which may attain the size of several inches,
resembling an ear or a mussel shell. In the moist condition they
are flesh-coloured, tough and gelatinous, but when dried, become
hard, grey and wrinkled; the exterior is covered with short
hairs; while the internal surface bears the hymenium. Habitat:
stems and branches of old Elder-trees (_Sambucus_).

Order 3. =Tremellaceæ.= The _round, pear-shaped, longitudinally divided basidia_ bear 4 _elongated sterigmata_, situated apically, and 4 basidiospores (Fig. 160 _C_, _D_), and are united into the _hymenium_ on the surface of the fruit-body. The fruit-bodies are frequently gelatinous and quivering; similar fruit-bodies are also found in the Dacryomycetaceæ and Hydnaceæ. Simple conidiophores, which appear not infrequently in the basidiocarps, before the basidia, are known in many species. Saprophytes.

_Exidia_ has kidney-shaped, oblong basidiospores, and small,
hook-like conidia; _E. glandulosa_, _E. albida_, etc., on
wood.--_Craterocolla_ has conidiocarps; _C. cerasi_ on
Cherry-wood.--_Sebacina incrustans_; the yellow, fleshy, or
cartilaginous fruit-bodies are found in autumn covering the
ground in moist woods.--_Tremella_ has round basidiospores;
_T. mesenterica_ has irregularly-folded, quivering, orange
fruit-bodies, about one inch in breadth; _T. lutescens_ (Fig.
161) has orange-yellow conidial-and yellow basidial-layers; _T.
frondosa_ has fruit-bodies upwards of a foot in breadth.

Order 4. =Pilacraceæ.= The _transversely divided basidia_ have _no sterigmata_, but sessile basidiospores, and fill up the cavity of a _closed_ (_angiocarpic_) _fruit-body_ as a gleba without a regular arrangement (hymenium wanting).

_Pilacre fagi_ on the old stems of the Copper-Beech; _P.
petersii_, on dried branches of the Hornbeam, has stalked,
capitate fruit-bodies.

Series 2. =Autobasidiomycetes.=

This second and larger part of the Basidiomycetes is characterised by its more highly differentiated, _undivided_, club-shaped, or cylindrical basidia, which generally bear 4 (seldom 2, 6, 8) apically-placed sterigmata and basidiospores (Fig. 145). The fruit-bodies are partly _gymnocarpic_ (in the first 3 orders and in some Agaricaceæ), partly _hemiangiocarpic_ (in orders 3–6 of the Hymenomycetes and in the Phalloideæ, the fruit-bodies in these orders are in the young conditions more or less angiocarpic, but later on generally open below and bear the hymenium on the under surface of the fruit-body), partly also _angiocarpic_ (in the Gasteromycetes).

Family 1. =Dacryomycetes.=

The _long, club-shaped basidia_ bear _two tapering sterigmata_, which develope remarkably large basidiospores (Fig. 162 II, XI) and form _gymnocarpic_ fruit-bodies with hymenium. 1 order:

Order 1. =Dacryomycetaceæ.= This order comprises 4 genera of which the first two develope the hymenium on the whole surface of the fruit-body, but the two last only on its apex.

_Dacryomyces_: the folded, gelatinous, _Tremella_-like
fruit-bodies break out in winter on dried wood (hedges) in
the form of red or yellow drops. _D. deliquescens_ is very
common (Fig. 121). The following genera have cartilaginous
fruit-bodies.--_Calocera_ (Fig. 162), with club-like, simple,
or branched, _Clavaria_-like, fruit-bodies; the orange coloured
fruit-bodies of _C. viscosa_ grow aggregated together on the
wood of Conifers.--_Guepinia_ resembles a _Peziza_, and has
the hymenium only on the hollow upper surface.--_Dacryomitra_
resembles a _Mitrula_ (Fig. 162).

Family 2. =Hymenomycetes.=

This family is very rich in species (more than 8000 have been described), and to it belong all the “Mushrooms” and “Toadstools.” The _fruit-bodies_ present very various forms; they are generally fleshy, very perishable, seldom leathery or corky, in the last case often perennial. The _basidia_ are more or less _cylindrical_ and bear _generally_ 4 (seldom 2, 6 or 8) _sterigmata and basidiospores_. The hymenium in the fully-formed fruit-bodies lies free on the surface: in orders 1 and 2 and a portion of order 6 it is from the commencement exposed, fruit-bodies _gymnocarpic_; orders 3–6 have _hemiangiocarpic_ fruit-bodies (p. 157). In the first order the basidia (or the hymenium) are developed immediately from the mycelium (Fig. 163); the fruit-bodies of orders 2 and 3 present a higher grade of development, and have between the mycelium and hymenium a special hyphal-tissue, a _stroma_, which is crustaceous, club-like, or coralloid, etc., and in general bears the hymenium on the largest part of the free, smooth surface. In the forms most highly developed (orders 4–6) a new tissue--the _hymenophore_--is introduced between the stroma and hymenium, which appears on the under side of the fruit-body in the form of warts, projections, tubes, folds or lamellæ (Figs. 166, 167, 174 _bc_). _Paraphyses_ are frequently found in the hymenium, among the basidia. In the Hymenomycetes few examples of _conidia_ can be recognised at first. More frequently _chlamydospores_ are found, particularly _oidia_. The _mycelium_ is richly branched, generally colourless, often perennial; it lives in humus or decaying wood, and is seldom parasitic. The hyphæ generally have clamp-connections and unite, sometimes, to form a rhizomorpha (Fig. 177) or sclerotia with coloured, pseudo-parenchymatous covering.

Order 1. =Tomentellaceæ.= To this order belong the simplest of the Hymenomycetes. The basidia (Fig. 145) arise free and irregularly from the mycelium; a _hymenium_ is _entirely absent_ or _very slightly formed_ (in _Corticium_ it attains its highest development); _fruit-bodies_ are _also wanting_.--In general they form flaky, membranous or leathery coverings on bark and wood. Some are parasites.

_Hypochnus_ without conidia.--_Tomentella_ with conidiophores;
growing on wood or earth.--_Exobasidium vaccinii_ (Fig. 163),
a parasite on _Vaccinium_, _Andromeda_, _Arctostaphylos_, and
_Rhododendron_, forms flaky-powdery, white or red coverings and
may cause hypertrophy of the parts attacked. _E. warmingii_ is
parasitic on _Saxifraga_; _E. lauri_ causes outgrowths on the
stem of _Laurus canariensis_ as long as a finger, which formerly
were regarded as aerial roots.--_Corticium_ forms membranous
to leathery layers or crusts; _C. quercinum_ on wood and bark,
particularly Oak, is flesh-coloured; _C. cæruleum_ has a blue
hymenium; _C. giganteum_ on the bark of fallen Pine-trees.

Order 2. =Clavariaceæ.= The hymenium is situated on a stroma, and either completely _covers the smooth surface_ of the more or less fleshy _gymnocarpic fruit-body_, or is confined to a tolerably well defined _upper portion_ of it (_Typhula_). Paraphyses absent. The vertical, white, yellow, or red fruit-bodies are roundish or club-like, undivided or richly branched (Fig. 125). Generally on the ground in woods, seldom on tree-stems, etc.

GENERA: _Clavaria_, generally large Fungi with thick, round
branches. _C. botrytis_ has a very thick, tubercular stem with
numerous short, flesh-coloured branches: it has an agreeable
taste. _C. coralloides_ has a brittle, richly-branched
fruit-body (Fig. 164); basidia with two large spores. _C.
pistillaris_ consists of a single, undivided club of a
yellowish-white colour.--_Sparassis_ has compressed, leaf-like,
curled branches; _S. crispa_ has fruit-bodies as large as
a white cabbage-head, with an agreeable taste.--_Typhula_
and _Pistillaria_ are small Fungi with filamentous stalks,
terminating in a small club. The fruit-bodies of the former
often arise from a small, spheroid sclerotium; the latter is
distinguished by the basidia bearing only two spores.

Order 3. =Thelephoraceæ.= The hymenium is placed on a stroma and _covers the smooth surface_ of the leathery _hemiangiocarpic fruit-body_, generally _on its under side_. The edge of the stroma, which bounds the hymenium, is sometimes especially developed (_Stereum_). Saprophytes.

GENERA: _Thelephora_. The fruit-bodies in this genus are brown,
very irregularly shaped, and often lobed. The spores too are
brown, but in the other genera colourless. The species are found
growing on barren soil. _T. laciniata_ (Fig. 165) has imbricate,
semicircular, dark-brown pileus, which is jagged at the edge
and upper surface. The fruit-bodies are very often raised above
the ground, and although this species is not a parasite, yet
it destroys young seedlings by growing above and smothering
them.--_Stereum_ has a stiffer fruit-body, with a distinct,
fibrous, intermediate layer. It grows on bark and wood,
projecting like a series of imbricate brackets. _S. hirsutum_
is yellow; its free edge is provided with a number of stiff
hairs, the upper surface being divided into a number of zones.
_S. purpureum_ has a red-violet hymenium which distinguishes
it from the previous species.--_Cyphella_ has a membranous
cup- or bell-shaped fruit-body, often borne on a stalk, the
concave surface being covered with the hymenium. They are small,
white Fungi, growing on Moss and dead stems.--_Solenia_ is
closely related to _Cyphella_; its fruit-bodies are smaller and
hairy; they are found clustered together forming a crust-like
covering on dead wood.--_Craterellus_ has a large, funnel-shaped
fruit-body, the hymenium covering the external surface.
_C. cornucopioides_ is shaped like a trumpet or a “horn of
plenty.” It is dark-grey, several inches in height, and grows
gregariously on the ground in forests. It is distinguished by
the basidia bearing only two sterigmata.

Order 4. =Hydnaceæ.= The fruit-body is most frequently fleshy, and varies considerably in shape, the simplest forms being resupinate,[14] the higher ones umbrella-like. The _hymenophore_ is found on the free or downward-turned surface, and always takes the _form of soft emergences_ hanging vertically downwards. The emergencies may be thorn-, awl-, or wart-like. The species are found growing on the soil and on dead wood.

GENERA: _Hydnum_ has subulate, distinct emergences. _H.
repandum_ is yellow, the stalk being placed in the centre of the
pileus. It is an edible species, and often forms “fairy rings”
in woods. _H. auriscalpium_ (Fig. 166) is dark-brown, with stalk
placed at the edge of the pileus. It grows on old Fir-cones. _H.
erinaceus_ grows on old tree-trunks. The fruit-body is yellow
and very large--as big as a human head--with emergences as much
as an inch in length.--_Irpex_ has a leathery fruit-body, partly
resupinate, partly with free, projecting edge; the under side
bears tooth-like emergences which are arranged in rows, and
_Irpex_ thus forms a transition to the Agaricaceæ.--_Phlebia_
is entirely resupinate, with radially-arranged folds on the free
side, and pectinate border.

Order 5. =Polyporaceæ (Pore-Fungi).= An order very rich in species (about 2000 species are described). The fruit-body is of very different forms--resupinate, projecting like a bracket, hoof-like, or umbrella-shaped. In some it is fleshy and edible, in others leathery or corky, persisting for several years. The hymenophore is situated on the under side of the fruit-body, and consists of wide or narrow _tubes_ or _pores_, whose inner surface is clothed with the hymenium (Fig. 167). In some fruit-bodies large cavities are to be found, which have arisen as interstices between the labyrinthine curved and reticulate folds. Chlamydospores are known in some species. Conidia occur very rarely. Many species work considerable damage: some as parasites on trees, others by destroying timber.

GENERA. _Polyporus_ (Pore-Fungus). The tubes are narrow,
accurately fitted together, and forming a thick layer on the
under side of the fruit-body, appearing as a number of fine
holes. The fruit-body most frequently resembles a bracket, or
is hoof-shaped, with one side growing from a tree-trunk; it
is very often perennial, and a new layer of tubes arises in
each succeeding period of vegetation. Strata, corresponding
to the periodically interrupted growth, are thus formed in
storeys one above the other, and are visible on the upper
surface of the fruit-body, as well as in the interior, as a
series of concentric belts, sometimes as many as half a score
or more in number. _P. fomentarius_ (Touchwood) attacks
trees, especially the Beech. The spores germinate on wounds
from broken branches, and the hyphæ, following the course of
the medullary rays, find their way into the interior of the
tree, from whence the mycelium spreads upwards, downwards, and
peripherally, so that the wood becomes rotten (“white-rot”) and
thick felts of mycelium are formed in radial and tangential
directions. A dark line, caused by the youngest parts of the
hyphæ containing a brown juice, marks the boundary between
the rotten and the unattacked parts of the stem (Fig. 168);
at places where the mycelium extends to the bark, the cambium
becomes destroyed and further growth is arrested, so that
longitudinal furrows arise on the stem. It is at these places,
too, that the hoof-shaped, ash-coloured fruit-bodies are
developed, which may attain a circumference of upwards of 7
feet. The interior of the fruit-body consists of a dried-up,
loosely felted, red-brown mass of hyphæ, which has been used for
tinder and as a styptic (“Fungus chirurgorum”). _P. igniarius_
has a harder, dark-brown, more rounded fruit-body; it grows in
a similar manner, but especially attacks Oaks, Poplars, and
Plum-trees, the wood of which becomes rotten, and is called
touchwood. _P. pini_ (_Trametes pini_), (Fig. 170), a parasite
on the stems of _Pinus_, causes a kind of “red-rot” in the
stem. _P. sulphureus_ has a soft, cheesy, yellow fruit-body;
it produces “rot” in Oaks and Apple-trees. _P. officinalis_,
Larch-fungus (“Fungus Laricis” in Pharmocopœia), grows on
Larch-trees in the south-east of Europe. _P. versicolor_ has
thin, semicircular fruit-bodies, with zones of various colours
on the upper side; it is one of the most frequent species on
tree-stems. _P. frondosus_ grows on soil in woods, and consists
of numerous aggregated fruit-bodies, which become very large
and fleshy. This species is edible. _P. perennis_ also grows on
the soil in woods; it is very leathery, with central stalk, and
has concentric zones on the upper surface of the fruit-body.
_P. vaporarius_ destroys the wood of living Pines (_Pinus
silvestris_) and Firs (_Picea excelsa_), causing it to become
red-brown; in timber this Fungus causes “red-strip” followed by
a “dry-rot.” _P. squamosus_ destroys many Walnut-trees, and is
also very destructive to Limes and Elms. _P. fulvus_ causes a
“white-rot” in _Abies alba_.

_Heterobasidion annosum_ (_Polyporus annosus_, _Trametes
radiciperda_, Fig. 169) is characterized by its
_Aspergillus_-like conidiophores. It is a parasite on the
Pine, Fir, Birch, Beech, etc., and is the chief cause of a
root-disease (red-rot) in Pines and Firs; the fruit-bodies
develope a large number of basidiospores; they may be very large
and are found just beneath the surface of the soil (on living or
dead roots), and exposed to the air (on felled stems and roots,
in Scandinavia).

_Ptychogaster_ has cushion-like fruit-bodies, which consist
chiefly of chlamydospore-chains, formed of ellipsoidal spores,
which alternate with short hyphæ having transverse septa and
clamp-connections. The hymenial portion is limited to a small
group of tubes. _Pt. albus_ (_Oligorus ustilaginoides_) grows
on stumps of Conifers and forms irregular cushions, at first
white and later on brown, which consist almost entirely of
chlamydospores.

_Boletus_ (Fig. 171) has a fleshy fruit-body resembling a common
Mushroom, with central stalk. The layer of tubes is easily
detached from the pileus, and the tubes are easily separable
from one another. They grow on the ground in woods. Edible
species are: _B. edulis_, with thick, reticulate stalk; _B.
scaber_, with thin stalk and rough pileus; _B. luteus_, with a
ring on the stalk. _B. luridus_ is poisonous, its tubes have
red openings, and the flesh turns quickly blue when broken and
exposed to the air.

_Fistulina hepatica_ (Beef-steak Fungus), has a red, fleshy,
edible fruit-body, with red juice. The tubes are individually
distinct; conidia are also developed. Grows on old Oaks.

_Merulius lacrymans_ (“Dry-rot”) has a resupinate fruit-body
with white, cotton-like border, and the remaining portions
covered by reticulate, ramified veins of a rust-brown colour.
In favourable vegetative conditions it is fleshy and exudes
large drops of water--hence its specific name and also the name
“Tear Fungus.” The mycelium is at first colourless, and then
yellow-brown; when dry it is tough and leathery. It destroys
the timber in damp houses, extends far and wide over boards and
beams and even over the masonry, giving rise to a disagreeable
smell in the rooms in which it lodges. In woods the Fungus lives
on Pine-stems. It is brought from the forest on the logs of
timber, and is distributed from log to log by the mycelium and
the basidiospores. The living mycelium can be recognised by the
clamp-connections shooting out branches. The basidiospores are
often ejected a distance of a metre; they are elliptical (10–11µ
long and 5–6µ broad), and germinate easily on damp wood, or in
fruit-juice which has been neutralized with urine or alkaline
carbonates.

_Dædalea_ (Labyrinth Fungus), has bracket-like, corky
fruit-bodies with irregularly-folded plates or discs on the
under side. It forms a transition to the Agaricaceæ. _D.
quercina_ is frequent on Oak-stumps.

Order 6. =Agaricaceæ= (=Mushrooms=, =Toadstools=). _The hymenophore consists_ of knife-like plates (_lamellæ_, _gills_), which are situated on the under side of the umbrella-like pileus of the fruit-body, and radiate from the central stalk. Those which are first formed extend from the edge of the pileus to the stalk; those formed later reach only a longer or shorter portion of this distance, according to their age. In structure the lamellæ (Fig. 174) consist of a central mass of hyphæ, the _trama_, continuous with the hyphæ of the pileus; these terminate in a layer of shorter cells, the _subhymenial layer_, immediately beneath the hymenium which is composed of basidia and paraphyses. In a few species, but not in the majority, the lamellæ are branched, and in some they are decurrent. A few have the stalk placed excentrically, or it may be entirely absent.

In the early stages of its development the fruit-body is more or less enclosed in a hyphal tissue--the “veil” (_velum universale_, or _volva_). The veil at first completely encloses the young fruit-body, but is afterwards ruptured as the latter grows, part remaining at the base of the stalk as the “sheath” (_annulus inferus_), and part on the pileus as scales or warts. In the “Fly Mushroom” (_Amanita muscaria_) the remains of the veil are especially conspicuous as white patches on the bright red ground of the upper surface of the pileus, and as a sheath at the base of the stalk (Fig. 178 _v._). Another veil--the _velum partiale_--a hyphal tissue (Figs. 178 _a_; 173) stretches from the edge of the pileus to the stalk, and encloses the lamellæ. This veil is ruptured as the pileus expands, a portion attached to the stalk remaining as the “upper ring” (_annulus superus_) (Figs. 173, 178 _a_), or a part attached to the pileus hanging down as a fringe round its edge.--Some genera have no veil, the under side of the pileus being exposed from the first (_gymnocarpic_ Agaricaceæ). Those which have a veil (_hemiangiocarpic_ A.) afford a transition to the angiocarpic Gasteromycetes.

The mycelium mostly grows in soils rich in humus or dung, on decaying trees and similar objects. Many species, _e.g. Tricholoma personatum_ and _Marasmius oreades_, form the so-called “fairy rings.” The fruit-bodies in these species are confined to a larger or smaller surface on which they are very regularly arranged in a ring. The reason for this is found in the radial growth of the mycelium, so that the oldest portion, or the starting point, is found at the centre of the ring, and the younger ones, on which the fruit-bodies are formed, at the circumference. The older hyphæ gradually die, and at the same time, the radial growth continuing, the ring of fruit-bodies becomes larger and larger. The “fairy-rings” are marked not only by the fruit-bodies, but also by the more vigorous growth and darker colour of the grass upon these spots.

Some species are _parasites_. An example is presented by _Armillaria mellea_, a remarkable and very destructive Fungus in woods and forests (Figs. 176, 177). ~In addition to the filamentous, white mycelium, it has also black, or black-brown, horny, root-like mycelium-strands (rhizomorpha) which were formerly considered to belong to a special genus of Fungi described under the name “_Rhizomorpha_.” The mycelium lives parasitically on the Conifers and other trees, forcing its hyphæ into the bark and between the bark and wood, and thence penetrating into the wood so that the tree is very severely attacked. It may also live saprophytically, and clusters of fruit-bodies are often found on old stumps and stems, on old timber, and in the rich soil of woods. The rhizomorpha, living underground, can extend for considerable distances and infect the roots of neighbouring trees, and spreads in this way the diseases known as “Harzsticken” and “Bark-Canker,” which are very destructive to young trees.~

The chief characteristics by which the numerous genera are separated are the presence or the absence of the two kinds of veils, the nature of the fruit-body, the form, branching of the lamellæ, and their position and relation with respect to the stem, the shape of the pileus, the colour of the spores, etc., etc. A knowledge of the colour may be obtained by placing the pileus with the lamellæ turned downwards on a piece of white or coloured paper, so that the spores, as they fall off, are collected on the paper, and the arrangement of the lamellæ can then be clearly seen.

About 4,600 species belonging to this order have been described.

On account of the large number of species the order is divided
into several sections:

1. =Agaricinei=; fruit-body fleshy; lamellæ membranous,
knife-like, with sharp edge; basidia crowded together. The
FOLLOWING HAVE WHITE SPORES:--_Amanita_ (Fly Mushroom), with
volva, and generally also the upper ring on the stalk; many are
poisonous, such as _A. muscaria_ (Fig. 178) which has bright red
pileus with white spots, _A. pantherina_ and _A. phalloides_;
_A. cæsarea_ is edible.--_Lepiota procera_ (Parasol Fungus)
is one of the largest Mushrooms; it has a scaly pileus and
moveable ring (edible).--_Armillaria mellea_ has been mentioned
above (Figs. 176, 177).--_Tricholoma_, lamellæ indented near
the stalk; _T. gambosum_ (Pomona Fungus) belongs to the best
of edible Fungi; _T. personatum_ often forms fairy rings (see
above).--_Clitocybe_, lamella decurrent; _C. nebularis_ is
edible.--_Pleurotus_, stalk eccentric; _P. ostreatus_ (Oyster
Mushroom) grows in clusters on tree-stems (edible).--_Collybia_
and _Mycena_, species numerous, small.--SPORES ROSE-RED:
_Volvaria_ and _Hyporhodius_.--SPORES BROWN: _Cortinarius_,
with cobweb-like veil; _Pholiota_, membranous veil and ring;
_P. squarrosa_ in clusters on tree-stems; _P. mutabilis_, on
tree-stumps (edible).--SPORES VIOLET-PURPLE: _Hypholoma_,
_Psalliota_; to this section the common edible Mushroom (Fig.
172–174) belongs, with annulus and chocolate-coloured lamellæ;
it is cultivated for the sake of the fine flavour.--SPORES
BLACK: _Coprinarius_.

2. =Marasmiei.= Fruit-body tough, almost leathery, and
persistent; spores white. _Marasmius oreades_ forms large,
regular fairy-rings on pastures and commons; it is used as
seasoning in food.--_Panus stipticus_ with eccentrically-placed
stalk, in clusters on tree-stumps.--_Schizophyllum_ has the edge
of the lamellæ divided longitudinally, and the split portions
revolute.--_Lentinus_ affords a transition to _Dædalea_ among
the Polyporaceæ.

3. =Russulei.= Fruit-body fleshy and fragile, in which two
different systems of hyphæ may be distinguished; spores thorny,
white, or pale-yellow. Many are poisonous.--_Russula_ has
generally fragile and thick lamellæ reaching from stalk to edge
of pileus; pileus frequently red.--_Lactarius_ has white or
yellow milky juice, which often is very acid. _L. deliciosus_
has red-yellow milky juice, and is of a pleasant flavour. _L.
torminosus_ is poisonous.

4. =Hygrophorei.= Lamellæ thick and waxy, widely separated;
spores white. Many species of _Hygrophorus_ have
brightly-coloured pileus and grow among the grass on moors and
commons.--_Nyctalis_ is parasitic on larger Toadstools. It is
remarkable for its abundant formation of chlamydospores, whilst
the basidiospores are little developed.

5. =Coprinei.= Fruit-bodies very soft, quickly perishable;
lamellæ membranous and deliquescent. The basidia are separated
from each other by paraphyses. _Coprinus_ has coal-black spores,
grows on manure, and sometimes developes sclerotia.

6. =Paxillei.= Fruit-body fleshy; lamellæ easily detached from
the pileus and reticulately-joined near the stalk. They form a
connecting link between the Agaricaceæ and _Boletus_.

7. =Cantharellei.= Lamellæ reduced to dichotomously-divided
folds, decurrent on the stalk. _Cantharellus cibarius_ (Fig.
175) is yolk-yellow, and grows on the ground in woods (edible).
It is allied to _Craterellus_.

Family 3. =Phalloideæ.=

The fruit-bodies before they are ripe are spherical or ovoid, and enclosed by a _fleshy covering_, the peridium, which is _perforated at maturity_ and remains as a sheath (Fig. 179); the fruit-bodies are _hemiangiocarpic_.

Order 1. =Phallaceæ= (=Stink-horns=). The peridium has a complicated structure and is composed of three layers, the intermediate one being thick and gelatinous. The gleba (the tissue which bears the hymenium) is situated upon a peculiar receptacle which expands into a porous stalk and by its sudden distension, rupturing the peridium, elevates the gleba and hymenium above the peridium, which remains as a sheath. _The gleba becomes gelatinous and dissolves away as drops._ To this order belong many peculiar and often brightly coloured forms, which are natives of the Southern Hemisphere.

_Phallus impudicus_ (Stink-horn) (Fig. 179), has a fruit-body
which at first is white, heavy, and soft, and resembles a hen’s
egg in shape and size. The peridium is divided into three layers
(Fig. 179 _e_, _g_, _f_) of which the external and internal
are membranous, and the middle one very thick and gelatinous;
each of these has again a laminated structure. The peridium
when ruptured remains as a sheath (_k_) at the base of the
stalk. The receptacle at first is strongly compressed (_h_)
but afterwards expands into a long stalk (_l_) which bears the
conical gleba (_m_). Prior to the rupture of the peridium the
gleba consists of a greenish mass (_i_) which, when exposed,
emits a carrion-like stench serving to attract flies, by whose
agency the spores are distributed. It is found commonly in
hedgerows and in woods, growing on the ground. The much smaller
and less common _P. caninus_ is found on rotten tree-stumps.--In
_Clathrus cancellatus_ the receptacle expands into a bright red,
reticulate structure. A native of the South of Europe. _Colus_,
_Aseroë_, _Mitromyces_.

Order 2. =Sphærobolaceæ.= An intermediate layer of the
_peridium_ swells when ripe, becomes convex, and _ejects the
remaining_ spherical _portion of the fruit-body_ which contains
the spores. _Sphærobolus carpobolus_ has small, spherical
fruit-bodies which open in the form of a star.

Family 4. =Gasteromycetes.=

The fruit-body is _angiocarpic_, fleshy at first, and later generally more or less _hard_ and _continues closed after the_ spores _are ripe_. The tissue lying immediately inside the _peridium_ is termed the _gleba_; it is porous, containing a larger or smaller number of chambers lined with the hymenium, which is either a continuous layer of basidia or else it fills up the entire cavity. The basidia as a rule bear four spores, sometimes eight (_Geaster_), or two (_Hymenogaster_). The tissue of the walls (_trama_) consists often (_Lycoperdaceæ_) of two kinds of hyphæ, some thin and rich in protoplasm, divided by transverse septa and bearing the basidia; others thicker and thick-walled which do not dissolve like the former on the ripening of the spores, but continue to grow and form a woolly, elastic mass, the _capillitium_, which may be regarded as highly developed paraphyses. The peridium may be either single or double, and presents many variations in its structure and dehiscence. The mycelium is generally a number of string-like strands, living in soils rich in humus.

Order 1. =Tylostomaceæ.= Capillitium present. After the rupture
of the peridium the remaining part of the fruit-body is elevated
on a long _stalk_. _Tylostoma mammosum_, on heaths.

Order 2. =Lycoperdaceæ.= The fruit-body has a double peridium; the external one at length breaks into fragments (_Lycoperdon_, _Bovista_), or it has a compound structure of several layers (_Geaster_) and detaches itself as a continuous envelope from the inner layer, which is membranous and opens at its apex. The interior of the fruit-body consists either solely of the fertile gleba (_Bovista_, _Geaster_), or, in addition, of a sterile tissue at the base (_Lycoperdon_). A capillitium is also present.

_Lycoperdon_ (Puff-ball) has a sterile part at the base of the
fruit-body which often forms a thick stalk. The surface of the
peridium is generally covered with warts or projections. When
young this Fungus is edible, but when ripe it is dry, and used
for stopping the flow of blood. _L. giganteum_, which is often
found growing in meadows, attains a considerable size, its
diameter reaching as much as eighteen inches. _L. gemmatum_
(Fig. 180) is covered with pyramidal warts; in woods.--_Bovista_
has no sterile basal part; the external peridium is smooth, and
falls away in irregular patches. _B. plumbea_, on links near the
sea.--_Geaster_ (Earth-star) has an external peridium composed
of several layers, which when the fruit-body opens, split into
several stellate segments. These segments are very hygroscopic,
and in dry weather bend backwards and so raise the inner
peridium into the air. The inner peridium contains the spores
and capillitia. _G. coliformis_ has several apertures in the
inner peridium. The other species have only one regular aperture
at the apex. _G. striatus_ has a pedicellate inner peridium,
with conical, striped peristome. _G. fornicatus_ has an external
peridium split into four segments. This last and several other
species produce “mycorhiza” on the roots of Conifers.

Order 3. =Sclerodermataceæ.= _Capillitium_ wanting. The peridium is simple and thick, gleba with round, closed chambers, which are filled with basidia.

_Scleroderma_ has a corky peridium. The fruit-bodies commence
their development under ground. _S. vulgare_ (Fig. 181 V-VII),
has a hard, slaty-black gleba.

Order 4. =Nidulariaceæ= (=Nest-Fungi=). Small Fungi of which the fruit-body at first is spherical or cylindrical but upon maturity it becomes cupular or vase-like, and contains several lenticular “peridiola” lying like eggs in a nest. The peridiola are the chambers which contain the hymenium, covered by a thin layer of the gleba, all the remaining portion of the gleba becoming dissolved. On decaying wood.

_Nidularia_ has spherical fruit-bodies containing a
large number of lenticular peridiola, embedded in a slimy
mass.--_Crucibulum_ has fruit-bodies resembling crucibles
with discoid peridiola, each with a spirally-twisted
stalk.--_Cyathus_ has a fruit-body, which when open is
campanulate, with stratified peridium, and long-stalked,
lense-shaped peridiola.

Order 5. =Hymenogastraceæ.= Fruit-bodies tubercular, globose and subterranean, resembling very closely the Truffles, from which they can only be distinguished with certainty by microscopic means. The peridium is simple, capillitium wanting, and the gleba encloses a system of labyrinthine passages covered with a continuous hymenium. The fruit-bodies persist for some time, and form a fleshy mass, the spores being only set free by the decay of the fruit-body, or when it is eaten by animals. The majority are South European. _Hymenogaster_, _Melanogaster_, _Rhizopogon_ (Fig. 181 I-IV).

APPENDIX TO THE BASIDIOMYCETES:

Basidiolichenes (Lichen-forming Basidiomycetes).

Several Fungi belonging to the Basidiomycetes have a symbiotic relationship with Algæ exactly similar to that enjoyed by certain Ascomycetes, and these are therefore included under the term Lichens (p. 136). They are chiefly tropical.

Order 1. =Hymenolichenes.= To this order belong some gymnocarpic forms: _Cora_, _Dictyonema_, _Laudatea_.[15]

Order 2. =Gasterolichenes.= To this belong some angiocarpic forms: _Emericella_, _Trichocoma_.