the paraphyses, (2) the asci, and sometimes (3) an investing mucilage.
The asci are always present, the paraphyses are sometimes rare, and
the mucilage in many cases seems to be entirely wanting.
The paraphyses, which are formed at the first commencement of the
receptacle, are at first very short, but soon elongate, and become
wholly developed before the appearance of the asci. They are linear,
sometimes branched and sometimes simple, often more or less thickened
at their tips; almost always they contain within them some oleaginous
granules, either coloured or colourless. Their special function seems
still somewhat obscure, and Boudier suggests that they may be
excitatory organs for the dehiscence of the asci. However this may be,
some mycologists are of opinion that, at least in some of the
Ascomycetes, the paraphyses are abortive asci, or, at any rate, that
abortive asci mixed with the paraphyses cannot be distinguished from
them.
The mucilage forms itself almost at the same time as the paraphyses,
and previous to the formation of the asci. This substance appears as a
colourless or yellowish mucilage, which envelopes the paraphyses and
asci, and so covers the hymenium with a shining coat.
The asci appear first at the base of the paraphyses, under the form of
oblong cells, filled with colourless protoplasm. By rapid growth, they
soon attain a considerable size and fulness, the protoplasm being
gradually absorbed by the sporidia, the first indication of which is
always the central nucleus. The mucilage also partly disappears, and
the asci, attaining their maturity, become quite distinct, each
enclosing its sporidia. But before they take their complete growth
they detach themselves from the subhymenial tissue, and being
attenuated towards their base, are forced upwards by pressure of the
younger asci, to, and in some instances beyond, the upper surface of
the disc. This phenomenon commences during the night, and continues
during the night and all the morning. It attains its height at
mid-day, and it is then that the slightest breath of air, the
slightest movement, suffices to cause dehiscence, which is generally
followed by a scarcely perceptible contractile motion of the
receptacle.
[Illustration: FIG. 34.--Asci, sporidia, and paraphyses of _Ascobolus_
(Boudier).]
There is manifestly a succession in formation and maturity of the asci
in a receptacle. In the true _Ascobolei_, in which the sporidia are
coloured, this may be more distinctly seen. At first some thin
projecting points appear upon the disc, the next day they are more
numerous, and become more and more so on following days, so as to
render the disc almost covered with raised black or crystalline
points;[z] these afterwards diminish day by day, until they ultimately
cease. The asci, after separation from the subhymenial tissue,
continue to lengthen, or it may be that their elasticity permits of
extension, during expulsion. Boudier considers that an amount of
elasticity is certain, because he has seen an ascus arrive at
maturity, eject its spores, and then make a sharp and considerable
movement of retraction, then the ascus returned again, immediately
towards its previous limits, always with a reduction in the number of
its contained sporidia.
The dehiscence of the asci takes place in the _Ascobolei_, in some
species of _Peziza_, _Morchella_, _Helvella_, and _Verpa_, by means of
an apical operculum, and in other _Pezizæ_, _Helotium_, _Geoglossum_,
_Leotia_, _Mitrula_, &c., by a fissure of the ascus. This operculum
may be the more readily seen when the ascus is coloured by a drop of
tincture of iodine.
The sporidia are usually four or eight, or some multiple of that
number, in each ascus, rarely four, most commonly eight. At a fixed
time the protoplasm, which at first filled the asci, disappears or is
absorbed in a mucilaginous matter, which occupies its place, in the
midst of which is a small nucleus, which is the rudiment of the first
spore; other spores are formed consecutively, and then the substance
separates into as many sections as there are sporidia. From this
period each sporidium seems to have a separate existence. All have a
nucleus, which is scarcely visible, often slightly granular, but which
is quite distinct from the oleaginous sporidioles so frequent amongst
the Discomycetes, and which are sometimes called by the same name. The
sporidia are at first a little smaller than when mature, and are
surrounded by mucilage. After this period the sporidia lose their
nebulous granulations, whilst still preserving their nucleus; their
outlines are distinct, and, amongst the true _Ascobolei_, commence
acquiring a rosy colour, the first intimation of maturity. This colour
manifests itself rapidly, accumulating exclusively upon the epispore,
which becomes of a deep rose, then violet, and finally violet blue, so
deep as sometimes to appear quite black. There are some modifications
in this coloration, since, in some species, it passes from a vinous
red to grey, then to black, or from rose-violet to brown.
The epispore acquires a waxy consistence by this pigmentation, so that
it may be detached in granules. It is to this particular consistency
of the epispore that the cracks so frequent in the coloured sporidia
of _Ascobolus_ are due, through contraction of the epispore. As they
approach maturity, the sporidia accumulate towards the apex of the
asci, and finally escape in the manner already indicated.
In all essential particulars there is a great similarity in the
structure of the other Discomycetes, especially in their reproductive
system. In most of them coloured sporidia are rare. In some the
receptacle is pileate, clavate, or inflated, whilst in _Stictis_ it is
very much reduced, and in the lowest form of all, _Ascomyces_, it is
entirely absent. In the _Phacidiacei_, the structure is very similar
to that of the _Elvellacei_, whilst the _Hysteriacei_, with greater
affinities with the latter, still tend towards the _Pyrenomycetes_ by
the more horny nature of the receptacle, and the greater tendency of
the hymenium to remain closed, at least when dry. In some species of
_Hysterium_, the sporidia are remarkably fine. M. Duby[AA] has
subjected this group to examination, and M. Tulasne partly so.[AB]
SPHÆRIACEI.--In this group there is considerable variation, within
certain limits. It contains an immense number of species, and these
are daily being augmented. The general feature in all is the
presence of a perithecium, which contains and encloses the hymenium,
and at length opening by a pore or ostiolum at the apex. In some
the perithecia are simple, in others compound; in some immersed in
a stroma, in others free; in some fleshy or waxy, in others
carbonaceous, and in others membranaceous. But in all there is this
important difference from the Ascomycetes we have already had under
consideration, that the hymenium is never exposed. The perithecium
consists usually of an external layer of cellular structure, which
is either smooth or hairy, usually blackish, and an internal
stratum of less compact cells, which give rise to the hymenium.
[Illustration: FIG. 35.--Perithecium of _Sphæria_ and Section.]
As in the _Discomycetes_, the hymenium consists of asci, paraphyses,
and mucilage, but the whole forms a less compact and more gelatinous
mass within the perithecium. The formation and growth of the asci and
sporidia differ little from what we have described, and when mature
the asci dehisce, and the sporidia alone are ejected from the
ostiolum. We are not aware that operculate asci have yet been
detected. It has been shown in some instances, and suspected in
others, that certain moulds, formerly classed with _Mucedines_ and
_Dematiei_, especially in the genus _Helminthosporium_, bear the
conidia of species of _Sphæria_, so that this may be regarded as one
form of fruit.
Perithecia, very similar externally to those of _Sphæria_, but
containing spores borne on slender pedicels and not enclosed in asci,
have had their relations to certain species of _Sphæria_ indicated,
and these are no longer regarded so much as species of _Hendersonia_
or _Diplodia_ as the pycnidia of _Sphæria_. Other and more minute
perithecia, containing minute, slender stylospores in great numbers,
formerly classed with _Aposphæria_, _Phoma_, &c., but are now
recognized as spermogonia containing the spermatia of _Sphæriæ_. How
these influence each other, when and under what circumstances the
spermatia are instrumental in impregnation of the sporidia, is still
matter of mystery. It is clear, however, that in all these conidia,
macrospores, microspores, and some spermatia, or by whatever names
they may be called, there exists a power of germination. Tulasne has
indicated in some instances five or six forms of fruit as belonging to
one fungus, of which the highest and most perfect condition is a
species of _Sphæria_.
[Illustration: FIG. 36.--_Uncinula adunca._]
PERISPORIACEI.--Except in the perithecia rupturing irregularly, and
not dehiscing by a pore, some of the genera in this group differ
little in structure from the _Sphæriacei_. On the other hand, the
_Erysiphei_ present important and very interesting features. They
occur chiefly on the green parts of growing plants. At first there is
a more or less profuse white mycelium.[AC] This gives rise to chains
of conidia (_Oidium_), and afterwards small sphæroid projections
appear at certain points on the mycelium. These enlarge, take an
orange colour, ultimately passing into brown, and then nearly black.
Externally these perithecia are usually furnished with long,
spreading, intertwined, or branching appendages, sometimes beautifully
branched or hooked at their tips. In the interior of the receptacles,
pear-shaped or ovate asci are formed in clusters, attached together at
the base, and containing two or more hyaline sporidia. Other forms of
fruit have also been observed on the same mycelium. In an exotic
genus, _Meliola_, the fulcra, or appendages, as well as the mycelium,
are black, otherwise it is very analogous to such a genus of
_Erysiphei_ as _Microsphæria_. In _Chætomium_, the perithecia bristle
with rigid, dark-coloured hairs, and the sporidia are coloured. Our
limits, however, will not permit of further elucidation of the complex
and varied structure to be found amongst fungi.[AD]
[A] A curious case occurred some years since at Bury St. Edmunds,
which may be mentioned here in connection with the development
of these nodules. Two children had died under suspicious
circumstances, and an examination of the body of the latter
after exhumation was made, a report having arisen that the
child died after eating mushrooms. As certain white nodules
appeared on the inner surface of the intestines, it was at once
hastily concluded that the spores of the mushroom had
germinated, and that the nodules were infant mushrooms. This
appeared to one of us so strange, that application was made for
specimens, which were kindly forwarded, and a cursory glance
was enough to convince us that they were not fungoid. An
examination under the microscope further confirmed the
diagnosis, and the application of nitric acid showed that the
nodules were merely due to chalk mixture, which had been given
to the child for the diarrhetic symptoms under which he
succumbed.
[B] Ehrenberg compared the whole structure of an Agaric with that
of a mould, the mycelium corresponding with the hyphasma,
the stem and pileus with the flocci, and the hymenium with
the fructifying branchlets. The comparison is no less
ingenious than true, and gives a lively idea of the connection
of the more noble with the more humble fungi.--_Ehrb. de
Mycetogenesi._
[C] In _Paxillus involutus_ the hymenium may be readily torn off and
unfolded.
[D] This was well delineated in "Flora Danica," plate 834, as
observed in _Coprinus comatus_ as long ago as 1780.
[E] A. de Bary, "Morphologie und Physiologie der Pilze," in
"Hofmeister's Handbuch," vol. ii. cap. 5, 1866, translated in
"Grevillea," vol. i. p. 181.
[F] "Die Pollinarien und Spermatien von _Agaricus_," in "Botanische
Zeitung," Feb. 29 and March 7, 1856.
[G] "Essai d'une Flore mycologique de la Région de Montpellier."
Paris, 1863.
[H] Hoffmann, "Botanische Zeitung," 1856, p. 139.
[I] Corda, "Icones Fungorum hucusque cognitorum," iii. p. 41. Prague,
1839.
[J] Cooke, M. C., "Anatomy of a Mushroom," in "Popular Science
Review," vol. viii. p. 380.
[K] An attempt was made to show that, in _Agaricus melleus_, distinct
asci were found, in a certain stage, on the gills or lamellæ.
We have in vain examined the gills in various conditions, and
could never detect anything of the kind. It is probable that
the asci belonged to some species of _Hypomyces_, a genus of
parasitic Sphæriaceous fungi.
[L] It is not intended that the spores are always quaternate in
_Agaricini_, though that number is constant in the more typical
species. They sometimes exceed four, and are sometimes reduced
to one.
[M] The species long known as _Hydnum gelatinosum_ was examined by
Mr. F. Currey in 1860 (_Journ. Linn. Soc._), and he came to the
conclusion that it was not a good _Hydnum_. Since then it has
been made the type of a new genus (Hydnogloea B. and Br.
or, as called by Fries, in the new edition of "Epicrisis,"
_Tremellodon_, Pers. Myc. Eur.), and transferred to the
_Tremellini_. Currey says, upon examining the fructification,
he was surprised to find that, although in its external
characters it was a perfect _Hydnum_, it bore the fruit of a
_Tremella_. If one of the teeth be examined with the
microscope, it will be seen to consist of threads bearing
four-lobed sporophores, and spores exactly similar to
_Tremella_. It will thus be seen, he adds, that the plant
is exactly intermediate between _Hydnei_ and _Tremellini_,
forming, as it were, a stepping-stone from one to the other.
[N] Tulasne, L. R. and C., "Observations on the Organization of the
Tremellini," in "Ann. des Sci. Nat." 3^me sér. xix. (1853), pp.
193, &c.
[O] M. Léveillé, in "Ann. des Sci. Nat." 2^me sér. viii. p. 328; 3^me
sér. ix. p. 127; also Bonorden, "Handbuch der Mycologie," p.
151.
[P] Tulasne, in "Ann. des Sci. Nat." (loc. cit.) xix. pl. x. fig. 29.
Tulasne, "New Notes upon Tremellinous Fungi," in "Journ. Linn.
Soc." vol. xiii. (1871), p. 31.
[Q] Berkeley, M. J., "On the Fructification of Lycoperdon, Phallus,
&c.," in "Ann. Nat. Hist." 1840, vol. iv. p. 158, pl. 5.
Berkeley, M. J., "Introduction Crypt. Bot." p. 346.
[R] Tulasne, L. R. and C., "Fungi Hypogæi." Paris. Berkeley and
Broome, "British Hypogæous Fungi," in "Ann. Nat. Hist." 1846,
xviii. p. 74. Corda, "Icones Fungorum," vol. vi. pl. vii.
viii.
[S] Tulasne, "Sur le Genre _Secotium_," in "Ann. des Sci. Nat."
(1845), 3^me sér. vol. iv. p. 169, plate 9.
[T] Tulasne, L. R. and C., "De la Fructification des _Scleroderma_
comparée a celle des _Lycoperdon_ et des _Borista_," in "Ann.
des Sci. Nat." 1842, xvii. p. 5. Tulasne, L. R. and C., "Sur
les Genres Polysaccum et Geaster," in "Ann. des Sci. Nat."
1842, xviii. p. 129, pl. 5 and 6.
[U] Berkeley, "On the Fructification of Lycoperdon, &c.," in "Annals
of Natural History" (1840), iv. p. 155.
[V] Wigand, "Morphologie des Genres Trichia et Arcyria," in "Ann. des
Sci. Nat." 4^me sér. xvi. p. 223.
[W] Currey, "On Spiral Threads of Trichia," in "Quart. Journ. Micr.
Science" (1855), iii. p. 17.
[X] In some of the genera, as, for instance, in _Badhamia_,
_Enerthenema_, and _Reticularia_, the spores are produced
within delicate cells or cysts, which are afterwards absorbed.
[Y] Tulasne, "Essai d'une Monographie des Nidulariées," in "Ann. des
Sci. Nat." (1844), i. 41 and 64.
[Z] Berkeley, M. J., "Introduction, Crypt. Bot." p. 330.
[a] Berkeley, M. J., "Introduction, Crypt. Bot." p. 329.
[b] In the _Cæomacei_ and _Pucciniæi_ the term "pseudospore" would be
much more accurate.
[c] Léveillé, "Sur la Disposition Méthodique des Urédinées," in "Ann.
des Sci. Nat." (1847), vol. viii. p. 369.
[d] De Bary, "Champignons Parasites," in "Ann. des Sci. Nat." 4^me
sér. vol. xx.
[e] Tulasne, "Mémoire sur les Urédinées, &c.," in "Ann. des Sci.
Nat." (1854), vol. ii. p. 78.
[f] De Bary, "Ueber die Brandpilze," Berlin, 1853.
[g] Currey, in "Quart. Journ. Micr. Sci." (1857), vol. v. p. 119, pl.
8, fig 13.
[h] Cooke, "On Podisoma," in "Journal of Quekett Microscopical Club,"
vol. ii. p. 255.
[i] Tulasne, "Mémoire sur les Ustilaginées," in "Ann. des Sci. Nat."
(1847), vii. pp. 12 and 73.
[j] Corda, "Icones Fungorum," vol. iii. fig. 45.
[k] Cooke, "On Podisoma," in "Quekett Journal," vol. ii. p. 255.
[l] It may be a question whether _Graphiola_ is not more nearly
allied to _Trichocoma_ (Jungh Fl. Crypt. Javæ, p. 10, f. 7)
than to the genera with which it is usually associated.--M. J.
B.
[m] Cooke, "On Microscopic Moulds," in "Quekett Journal," vol. ii.
plate 7.
[n] _See_ "Dendryphium Fumosum," in "Quekett Journal," vol. ii. plate
8; or, "Corda Prachtflora," plate 22.
[o] De Bary, "Champignons Parasites," in "Ann. des Sci. Nat." 4^me
sér. vol. xx.
[p] Berkeley, "On the Potato Murrain," in "Journ. of Hort. Soc. of
London," vol. i. (1846), p. 9.
[q] De Bary, "On Mildew and Fermentation," p. 25, reprinted from
"German Quarterly Magazine," 1872; De Bary, "Morphologie und
Physiologie der Pilze," (1866), 201.
[r] Cooke, "Handbook of British Fungi," vol. ii. p. 552.
[s] De Bary, "On Mildew and Fermentation," in "Quarterly German
Magazine," for 1872.
[t] We are quite aware that Von Tieghem and Le Monnier, in "Ann. des
Sci. Nat." 1873, p. 335, dispute that this belongs to _Mucor
mucedo_, and assert that _Chætocladium Jonesii_ is itself a
true _Mucor_, with monosporous sporangia.
[u] Vittadini, "Monographia Tuberacearum," 1831.
[v] Tulasne, "Fungi Hypogæi," 1851.
[w] Corda, "Icones Fungorum," vol. vi.
[x] Berkeley and Broome, in "Ann. of Nat. Hist." 1st ser. vol. xviii.
(1846), p. 73; Cooke, in "Seem. Journ. Bot."
[y] Boudier (E.), "Mémoire sur les Ascobolés," in "Ann. des Sci.
Nat." 5^me sér. vol. x. (1869).
[z] Only in some of the Discomycetes are the asci exserted.
[AA] Duby, "Mémoire sur la Tribu des Hysterinées," 1861.
[AB] Tulasne, "Selecta Fungorum Carpologia," vol. iii.
[AC] Tulasne, "Selecta Fungorum Carpologia," vol. i. Léveillé,
"Organisation, &c., sur l'Érysiphé," in "Ann. des Sci. Nat."
(1851), vol. xv. p. 109.
[AD] Other works besides those already cited, which may be consulted
with advantage on structure, are--
Tulasne, L. R. and C., various articles in "Annales des
Sciences Naturelles," série iii. and iv.
Hoffmann, "Icones Analyticæ Fungorum."
De Bary, "Der Ascomyceten." Leipzic, 1863.
Berkeley, M. J., "Introduction to Cryptogamic Botany."
Seynes, J. de, "Recherches, &c., des Fistulines." Paris, 1874.
Winter, G., "Die Deutschen Sordarien." 1874.
Corda, J., "Prachtflora." Prague, 1840.
De Bary, "Über der Brandpilze." 1853.
Brefeld, O., "Botan. Untersuch. ü Schimmelpilze."
Fresenius, G., "Beiträge zur Mykologie." 1850.
Von Tieghem and Le Monnier, in "Annales des Sciences
Naturelles" (1873), p. 335.
Cornu, M., "Sur les Saprolegniées," in "Ann. des Sci. Nat."
5^me sér. xv. p. 5.
Janczenski, "Sur l'Ascobolus furfuraceus," in "Ann. des Sci.
Nat." 5^me sér. xv. p. 200.
De Bary and Woronin, "Beiträge zur Morphologie und Physiologie
der Pilze." 1870.
Bonorden, H. F., "Abhandlungen aus dem Gebiete der Mykologie."
1864.
Coemans, E., "Spicilége Mycologique." 1862, etc.
III
CLASSIFICATION
A work of this kind could not be considered complete without some
account of the systematic arrangement or classification which these
plants receive at the hands of botanists. It would hardly avail to
enter too minutely into details, yet sufficient should be attempted to
enable the reader to comprehend the value and relations of the
different groups into which fungi are divided. The arrangement
generally adopted is based upon the "Systema Mycologicum" of Fries, as
modified to meet the requirements of more recent microscopical
researches by Berkeley in his "Introduction,"[A] and adopted in
Lindley's "Vegetable Kingdom." Another arrangement was proposed by
Professor de Bary,[B] but it has never met with general acceptance.
In the arrangement to which we have alluded, all fungi are divided
into two primary sections, having reference to the mode in which the
fructification is produced. In one section, the spores (which occupy
nearly the same position, and perform similar functions, to the seeds
of higher plants) are naked; that is, they are produced on spicules,
and are not enclosed in cysts or capsules. This section is called
SPORIFERA, or spore-bearing, because, by general consent, the term
_spore_ is limited in fungi to such germ-cells as are not produced in
cysts. The second section is termed SPORIDIIFERA, or sporidia-bearing,
because in like manner the term _sporidia_ is limited to such
germ-cells as are produced in cells or cysts. These cysts are
respectively known as _sporangia_, and _asci_ or _thecæ_. The true
meaning and value of these divisions will be better comprehended when
we have detailed the characters of the families composing these two
divisions.
First, then, the section SPORIFERA contains four families, in two of
which a hymenium is present, and in two there is no proper hymenium.
The term _hymenium_ is employed to represent a more or less expanded
surface, on which the fructification is produced, and is, in fact, the
fruit-bearing surface. When no such surface is present, the fruit is
borne on threads, proceeding direct from the root-like filaments of
the mycelium, or an intermediate kind of cushion or stroma. The two
families in which an hymenium is present are called _Hymenomycetes_
and _Gasteromycetes_. In the former, the hymenium is exposed; in the
latter, it is at first enclosed. We must examine each of these
separately.