the temperature being about 22° Cent., all the young branches
brightened with an uniform phosphoric light the whole of their length;
it was the same with the surface of some of the older branches, the
greater number of which were still brilliant in some parts, and only
on their surface. I split and lacerated many of these twigs, but their
internal substance remained dull. The next evening, on the contrary,
this substance, having been exposed to contact with the air, exhibited
at its surface the same brightness as the bark of the branches. I made
this observation upon the old stalks as well as upon the young ones.
Prolonged friction of the luminous surfaces reduced the brightness
and dried them to a certain degree, but did not leave on the fingers
any phosphorescent matter. These parts continued with the same
luminous intensity after holding them in the mouth so as to moisten
them with saliva; plunged into water, held to the flame of a candle so
that the heat they acquired was very appreciable to the touch, they
still emitted in the dark a feeble light; it was the same after being
held in water heated to 30° C.; but putting them in water bearing a
temperature of 55° C. extinguished them entirely. They are equally
extinguished if held in the mouth until they catch the temperature;
perhaps, still, it might be attributed less to the heat which is
communicated to them than to the deficiency of sufficient oxygen,
because I have seen some stalks, having become dull in the mouth,
recover after a few instants a little of their phosphorescence. A
young stalk which had been split lengthwise, and the internal
substance of which was very phosphorescent, could imbibe olive oil
many times and yet continue for a long time to give a feeble light. By
preserving these _Rhizomorphæ_ in an adequate state of humidity, I
have been able for many evenings to renew the examination of their
phosphorescence; the commencement of dessication, long before they
really perish, deprives them of the faculty of giving light. Those
which had been dried for more than a month, when plunged into water,
commenced to vegetate anew and send forth numerous branches in a few
days; but I could only discover phosphorescence at the surface of
these new formations, or very rarely in their immediate neighbourhood,
the mother stalks appearing to have lost by dessication their luminous
properties, and did not recover them on being recalled to life. These
observations prove that what Schmitz has written was not true, that
all parts of these fungi were seldom phosphorescent.
The luminous phenomenon in question is without doubt more complicated
than it appears, and the causes to which we attribute it are certainly
powerfully modified by the general character of the objects in which
they reside. Most of the German botanists give this explanation,
others suppose that it forms at first or during its continuance a
special matter, in which the luminous property resides; this matter,
which is said to be mucilaginous in the luminous wood, appears to be
in the _Rhizomorpha_ only a kind of chemical combination between the
membrane and some gummy substance which they contain. Notwithstanding
this opinion, I am assured that all external mucous matter was
completely absent from the _Agaricus olearius_, and I neither
discovered it upon the branches of _Rhizomorpha subterranea_ nor upon
the dead leaves which I have seen phosphorescent; in all these objects
the luminous surfaces were nothing else than their proper tissue.
It may be remarked here that the so-called species of _Rhizomorpha_
are imperfect fungi, being entirely devoid of fructification,
consisting in fact only of a vegetative system--a sort of compact
mycelium--(probably of species of _Xylaria_) with some affinity to
_Sclerotium_.
Recently an extraordinary instance of luminosity was recorded as
occurring in our own country.[H] "A quantity of wood had been
purchased in a neighbouring parish, which was dragged up a very steep
hill to its destination. Amongst them was a log of larch or spruce, it
is not quite certain which, 24 feet long and a foot in diameter. Some
young friends happened to pass up the hill at night, and were
surprised to find the road scattered with luminous patches, which,
when more closely examined, proved to be portions of bark or little
fragments of wood. Following the track, they came to a blaze of white
light which was perfectly surprising. On examination, it appeared that
the whole of the inside of the bark of the log was covered with a
white byssoid mycelium of a peculiarly strong smell, but unfortunately
in such a state that the perfect form could not be ascertained. This
was luminous, but the light was by no means so bright as in those
parts of the wood where the spawn had penetrated more deeply, and
where it was so intense that the roughest treatment scarcely seemed to
check it. If any attempt was made to rub off the luminous matter it
only shone the more brightly, and when wrapped up in five folds of
paper the light penetrated through all the folds on either side as
brightly as if the specimen was exposed; when, again, the specimens
were placed in the pocket, the pocket when opened was a mass of light.
The luminosity had now been going on for three days. Unfortunately we
did not see it ourselves till the third day, when it had, possibly
from a change in the state of electricity, been somewhat impaired; but
it was still most interesting, and we have merely recorded what we
observed ourselves. It was almost possible to read the time on the
face of a watch even in its less luminous condition. We do not for a
moment suppose that the mycelium is essentially luminous, but are
rather inclined to believe that a peculiar concurrence of climatic
conditions is necessary for the production of the phenomenon, which is
certainly one of great rarity. Observers as we have been of fungi in
their native haunts for fifty years, it has never fallen to our lot to
witness a similar case before, though Prof. Churchill Babington once
sent us specimens of luminous wood, which had, however, lost their
luminosity before they arrived. It should be observed that the parts
of the wood which were most luminous were not only deeply penetrated
by the more delicate parts of the mycelium, but were those which were
most decomposed. It is probable, therefore, that this fact is an
element in the case as well as the presence of fungoid matter."
In all cases of phosphorescence recorded, the light emitted is
described as of the same character, varying only in intensity. It
answers well to the name applied to it, as it seems remarkably similar
to the light emitted by some living insects and other animal
organisms, as well as to that evolved, under favourable conditions, by
dead animal matter--a pale bluish light, resembling that emitted by
phosphorus as seen in a dark room.
Another phenomenon worthy of note is the change of colour which the
bruised or cut surface of some fungi undergo. Most prominent amongst
these are certain poisonous species of _Boletus_, such, for instance,
as _Boletus luridus_, and some others, which, on being bruised, cut,
or divided, exhibit an intense, and in some cases vivid, blue. At
times this change is so instantaneous that before the two freshly-cut
portions of a _Boletus_ can be separated, it has already commenced,
and proceeds rapidly till the depth of intensity has been gained.
This blue colour is so universally confined to dangerous species that
it is given as a caution that all species which exhibit a blue colour
when cut or bruised, should on no account be eaten. The degree of
intensity varies considerably according to the condition of the
species. For example, _Boletus cærulescens_ is sometimes only very
slightly, if at all, tinged with blue when cut, though, as the name
implies, the peculiar phenomenon is generally highly developed. It
cannot be said that this change of colour has as yet been fully
investigated. One writer some time since suggested, if he did not
affirm, that the colour was due to the presence of aniline, others
have contented themselves with the affirmation that it was a rapid
oxidization and chemical change, consequent upon exposure of the
surfaces to the air. Archdeacon Robinson examined this phenomenon in
different gases, and arrived at the conclusion that the change depends
on an alteration of molecular arrangement.[I]
One of the best of the edible species of _Lactarius_, known as
_Lactarius deliciosus_, changes, wherever cut or bruised, to a dull
livid green. This fungus is filled with an orange milky fluid, which
becomes green on exposure to the air, and it is consequently the juice
which oxidizes on exposure. Some varieties more than others of the
cultivated mushroom become brownish on being cut, and a similar change
we have observed, though not recorded, in other species.
The presence of a milky juice in certain fungi has been alluded to.
This is by no means confined to the genus _Lactarius_, in which such
juice is universal, sometimes white, sometimes yellow, and sometimes
colourless. In Agarics, especially in the subgenus _Mycena_, the gills
and stem are replete with a milky juice. Also in some species of
_Peziza_, as for instance in _Peziza succosa_, B., sometimes found
growing on the ground in gardens, and in _Peziza saniosa_, Schrad.,
also a terrestrial species, the same phenomenon occurs. To this might
be added such species as _Stereum spadiceum_, Fr., and _Stereum
sanguinolentum_, Fr., both of which become discoloured and bleeding
when bruised, while _Corticium lactescens_ distils a watery milk.
Fungi in general have not a good repute for pleasant odours, and yet
it must be conceded that they are not by any means devoid of odour,
sometimes peculiar, often strong, and occasionally very offensive.
There is a peculiar odour common to a great many forms, which has come
to be called a fungoid odour; it is the faint smell of a long-closed
damp cellar, an odour of mouldiness and decay, which often arises from
a process of eremocausis. But there are other, stronger, and equally
distinct odours, which, when once inhaled, are never to be forgotten.
Amongst these is the fetid odour of the common stinkhorn, which is
intensified in the more beautiful and curious _Clathrus_. It is very
probable that, after all, the odour of the _Phallus_ would not be so
unpleasant if it were not so strong. It is not difficult to imagine,
when one encounters a slight sniff borne on a passing breeze, that
there is the element of something not by any means unpleasant about
the odour when so diluted; yet it must be confessed that when carried
in a vasculum, in a close carriage, or railway car, or exposed in a
close room, there is no scruple about pronouncing the odour intensely
fetid. The experience of more than one artist, who has attempted the
delineation of _Clathrus_ from the life, is to the effect that the
odour is unbearable even by an enthusiastic artist determined on
making a sketch.
Perhaps one of the most fetid of fungi is _Thelephora palmata_. Some
specimens were on one occasion taken by Mr. Berkeley into his bedroom
at Aboyne, when, after an hour or two, he was horrified at finding the
scent far worse than that of any dissecting room. He was anxious to
save the specimens, but the scent was so powerful that it was quite
intolerable till he had wrapped them in twelve thick folds of the
strongest brown paper. The scent of _Thelephora fastidiosa_ is bad
enough, but, like that of _Coprinus picaceus_, it is probably derived
from the imbibition of the ordure on which it is developed. There
needs no stronger evidence that the scent must not only be powerful,
but unpleasant, when an artist is compelled, before a rough sketch is
more than half finished, to throw it away, and seek relief in the open
air. A great number of edible Agarics have the peculiar odour of
fresh meal, but two species, _Agaricus odorus_ and _Agaricus
fragrans_, have a pleasant anise-like odour. In two or three species
of tough _Hydnum_, there is a strong persistent odour somewhat like
melilot or woodruffe, which does not pass away after the specimen has
been dried for years. In some species of _Marasmius_, there is a
decidedly strong odour of garlic, and in one species of _Hygrophorus_,
such a resemblance to that of the larva of the goat moth, that it
bears the name of _Hygrophorus cossus_. Most of the fleshy forms
exhale a strong nitrous odour during decay, but the most powerful we
remember to have experienced was developed by a very large specimen of
_Choiromyces meandriformis_, a gigantic subterranean species of the
truffle kind, and this specimen was four inches in diameter when
found, and then partially decayed. It was a most peculiar, but strong
and unpleasantly pungent nitrous odour, such as we never remember to
have met with in any other substance. _Peziza venosa_ is remarkable
when fresh for a strong scent like that of aquafortis.
Of colour, fungi exhibit an almost endless variety, from white,
through ochraceous, to all tints of brown until nearly black, or
through sulphury yellow to reds of all shades, deepening into crimson,
or passing by vinous tints into purplish black. These are the
predominating gradations, but there are occasional blues and mineral
greens, passing into olive, but no pure or chlorophyllous green. The
nearest approach to the latter is found in the hymenium of some
_Boleti_. Some of the Agarics exhibit bright colours, but the larger
number of bright-coloured species occur in the genus _Peziza_. Nothing
can be more elegant than the orange cups of _Peziza aurantia_, the
glowing crimson of _Peziza coccinea_, the bright scarlet of _Peziza
rutilans_, the snowy whiteness of _Peziza nivea_, the delicate yellow
of _Peziza theleboloides_, or the velvety brown of _Peziza repanda_.
Amongst Agarics, the most noble _Agaricus muscarius_, with its warty
crimson pileus, is scarcely eclipsed by the continental orange
_Agaricus cæsarius_. The amethystine variety of _Agaricus laccatus_ is
so common and yet so attractive; whilst some forms and species
_Russula_ are gems of brilliant colouring. The golden tufts of more
than one species of _Clavaria_ are exceedingly attractive, and the
delicate pink of immature _Lycogala epidendrum_ is sure to command
admiration. The minute forms which require the microscope, as much to
exhibit their colour as their structure, are not wanting in rich and
delicate tints, so that the colour-student would find much to charm
him, and good practice for his pencil in these much despised examples
of low life.
Amongst phenomena might be cursorily mentioned the peculiar sarcodioid
mycelium of _Myxogastres_, the development of amoeboid forms from
their spores, and the extraordinary rapidity of growth, as the
well-known instance of the _Reticularia_ which Schweinitz observed
running over iron a few hours after it had been red hot. Mr. Berkeley
has observed that the creamy mycelium of _Lycogala_ will not revive
after it has become dry for a few hours, though so active before.
[A] M. J. Berkeley, "Introduction to Cryptogamic Botany," p. 265.
[B] Tulasne, "Sur la Phosphorescence des Champignons," in "Ann. des
Sci. Nat." (1848), vol. ix, p. 338.
[C] In "Hooker's Journal of Botany" (1840), vol. ii. p. 426.
[D] Berkeley, "Introduction to Crypt. Bot." t. 265.
[E] Dr. Collingwood, in "Journal of Linnæan Society (Botany)," vol.
x. p. 469.
[F] In "Hooker's Journal of Botany" for April, 1842.
[G] Tulasne, "Sur la Phosphorescence," in "Ann. des Sci. Nat."
(1848), vol ix. p. 340, &c.
[H] Rev. M. J. Berkeley, in "Gardener's Chronicle" for 1872, p.
1258.
[I] Berkeley, "Introduction to Crypt. Bot." p. 266.
VI.
THE SPORE AND ITS DISSEMINATION.
A work of this character would hardly be deemed complete without some
reference to the above subject, which has moreover a relation to some
of the questions discussed, and particularly of spore diffusion in the
atmosphere. The largest spore is microscopic, and the smallest known
scarcely visible under a magnifying power of 360 diameters. Taking
into account the large number of species of fungi, probably scarcely
less numerous than all the flowering plants, and the immense number of
spores which some of the individuals produce, they must be exceedingly
plentiful and widely diffused, though from their minuteness not easy
to be discerned. It has been attempted to estimate the number of
spores which might be produced by one single plant of _Lycoperdon_,
but the number so far exceeds that which the mind is accustomed to
contemplate that it seems scarcely possible to realize their
profusion. Recent microscopic examinations of the common atmosphere[A]
show the large quantity of spores that are continually suspended. In
these investigations it was found that spores and similar cells were
of constant occurrence, and were generally present in considerable
numbers. That the majority of the cells were living, and ready to
undergo development on meeting with suitable conditions, was very
manifest, as in those cases in which preparations were retained under
observation for any length of time, germination rapidly took place in
many of the cells. In few instances did any development take place,
beyond the formation of networks of mycelium, or masses of toruloid
cells, but, in one or two, distinct sporules were developed on the
filaments arising from some of the larger septate spores; and in a few
others, _Penicillium_ and _Aspergillus_ produced their characteristic
heads of fructification. With regard to the precise nature of the
spores, and other cells present in various instances, little can be
said, as, unless their development were to be carefully followed out
through all its stages, it is impossible to refer them to their
correct species or even genera. The greater number of them are
apparently referable to the old orders of fungi, _Sphæronemei_,
_Melanconei_, _Torulacei_, _Dematiei_ and _Mucedines_, while some
probably belonged to the _Pucciniæi_ and _Cæomacei_.
Hence it is demonstrated that a large number of the spores of fungi
are constantly present in the atmosphere, which is confirmed by
the fact that whenever a suitable pabulum is exposed it is taken
possession of by floating spores, and soon converted into a forest
of fungoid vegetation. It is admitted that the spores of such
common moulds as _Aspergillus_ and _Penicillium_ are so widely
diffused, that it is almost impossible to exclude them from closed
vessels, or the most carefully guarded preparations. Special
contrivances for the dispersion of the spores in the different groups
follow a few general types, and it is only rarely that we meet with
any method that is confined only to a species or genus. Some of
the more significant forms of spores may be illustrated, with their
modes of dissemination.
BASIDIOSPORES is a term which we may employ here to designate all
spores borne at the tips of such supports as are found in the
_Hymenomycetes_ and _Gasteromycetes_, to which the name of basidia has
been given. In fact, under this section we may include all the spores
of those two orders, although we may be ignorant of the precise mode
in which the fruit of most of the _Myxogastres_ is developed. Guarding
ourselves at the outset against any misinterpretation as to the use of
this term, which, in fact, we employ simply to designate the fruit of
_Hymenomycetes_, we may have excuse in our desire to limit special
terms as much as possible. In the _Agaricini_ the spores are
plentiful, and are distributed over the hymenium or gill plates, the
surface of which is studded with basidia, each of which normally
terminates with four short, erect, delicate, thread-like processes,
each of which is surmounted by a spore. These spores are colourless or
coloured, and it is upon this fact that primary divisions in the genus
_Agaricus_ are based, inasmuch as colour in the spores appears to be a
permanent feature. In white-spored species the spores are white in all
the individuals, not mutable as the colour of the pileus, or the
corolla in phanerogamic plants. So also with the pink spored, rusty
spored, black spored, and others. This may serve to explain why
colour, which is so little relied upon in classification amongst the
higher plants, should be introduced as an element of classification in
one of the largest genera of fungi.
[Illustration: FIG. 45.--Spores of (_a_) _Agaricus mucidus_; (_b_)
_Agaricus vaginatus_; (_c_) _Agaricus pascuus_; (_d_) _Agaricus
nidorosus_; (_e_) _Agaricus campestris_. (Smith.)]
[Illustration: FIG. 46.--Spores of (_a_) _Lactarius blennius_; (_b_)
_Lactarius fuliginosus_; (_c_) _Lactarius quietus_. (Smith.)]
There are considerable differences in size and form amongst the spores
of the _Agaricini_, although at first globose; when mature they are
globose, oval, oblong, elliptic, fusiform, and either smooth or
tuberculated, often maintaining in the different genera or subgenera
one particular characteristic, or typical form. It is unnecessary here
to particularize all the modifications which the form and colour of
the spores undergo in different species, as this has already been
alluded to. The spores in the _Polyporei_, _Hydnei_, &c., are less
variable, of a similar character, as in all the _Hymenomycetes_,
except perhaps the _Tremellini_.
[Illustration: FIG. 46a.--(_a_) Spore of _Gomphidius viscidus;_ (_b_)
spore of _Coprinus micaceus_.]
[Illustration: FIG. 47.--Spores of (_a_) _Polyporus cæsius_; (_b_)
_Boletus parasiticus_; (_c_) _Hydnum_.]
When an Agaric is mature, if the stem is cut off close to the gills,
and the pileus inverted, with the gills downwards on a sheet of black
paper (one of the pale-spored species is best for this purpose), and
left for a few hours, or all night, in that position, the paper will
be found imprinted in the morning with a likeness of the under side of
the pileus with its radiating gills, the spores having been thrown
down upon the paper in such profusion, from the hymenium, and in
greater numbers from the opposed surfaces of the gills. This little
experiment will be instructive in two or three points. It will
illustrate the facility with which the spores are disseminated, the
immense number in which they are produced, and the adaptability of the
gill structure to the economy of space, and the development of the
largest number of basidiospores from a given surface. The tubes or
pores in _Polyporei_, the spines in _Hydnei_, are modifications of the
same principles, producing a like result.
In the _Gasteromycetes_ the spores are produced in many cases, probably
in most, if not all, at the tips of sporophores; but the hymenium,
instead of being exposed, as in the _Hymenomycetes_, is enclosed within
an outer peridium or sac, which is sometimes double. The majority of
these spores are globose in form, some of them extremely minute,
variously coloured, often dark, nearly black, and either externally
smooth or echinulate. In some genera, as _Enerthenema_, _Badhamia_,
&c., a definite number of spores are at first enclosed in delicate
cysts, but these are exceptions to the general rule: this also is the
case in at least one species of _Hymenogaster_. As the spores approach
maturity, it may be observed in such genera as _Stemonitis_, _Arcyria_,
_Diachea_, _Dictydium_, _Cribraria_, _Trichia_, &c., that they are
accompanied by a sort of reticulated skeleton of threads, which
remain permanent, and served in earlier stages, doubtless, as
supports for the spores; being, in fact, the skeleton of the hymenium.
It has been suggested that the spiral character of the threads in
_Trichia_ calls to mind the elaters in the _Hepaticæ_, and like them
may, by elasticity, aid in the dispersion of the spores. There is
nothing known, however, which will warrant this view. When the spores
are mature, the peridium ruptures either by an external orifice, as
in _Geaster_, _Lycoperdon_, &c., or by an irregular opening, and the
light, minute, delicate, spores are disseminated by the slightest
breath of air. Specimens of _Geaster_ and _Bovista_ are easily
separated from the spot on which they grew; when rolling from place
to place, the spores are deposited over a large surface. In the
_Phalloidei_ the spores are involved in a slimy mucus which would
prevent their diffusion in such a manner. This gelatinous substance has
nevertheless a peculiar attraction for insects, and it is not altogether
romantic to believe that in sucking up the fetid slime, they also
imbibe the spores and transfer them from place to place, so that even
amongst fungi insects aid in the dissemination of species. Whether or
not the _Myxogastres_ should be included here is matter of opinion,
since the mode in which the spores are developed is but little known;
analogy with the _Trichogastres_ in other points alone leading to the
conclusion that they may produce basidiospores. The slender, elastic
stems which support the peridia in many species are undoubted aids to
the dissemination of the spores.[B]
[Illustration: FIG. 48.--_Diachea elegans._]