"I have seen a stipe opened and lacerated irregularly, the whole of the flesh of which remained phosph.o.r.escent during three consecutive evenings, but the brightness diminished in intensity from the exterior to the interior, so that on the third day it did not issue from the inner part of the stipe. The phosph.o.r.escence of the gills is in no way modified at first by immersing the fungus in water; when they have been immersed they are as bright as in the air, but the fungi which I left immersed until the next evening lost all their phosph.o.r.escence, and communicated to the water an already sensible yellow tint; alcohol put upon the phosph.o.r.escent gills did not at once completely obliterate the light, but visibly enfeebled it. As to the spores, which are white, I have found many times very dense coats of them thrown down on porcelain plates, but I have never seen them phosph.o.r.escent.

"As to the observation made by Delile that the Agaric of the olive does not shine during the day when placed in total darkness, I think that it could not have been repeated. From what I have said of the phosph.o.r.escence of _A. olearius_, one naturally concludes that there does not exist any necessary relation between this phenomenon and the fructification of the fungus; the luminous brightness of the hymenium shows, says Delile, 'the greater activity of the reproductive organs,'

but it is not in consequence of its reproductive functions, which may be judged only as an accessory phenomenon, the cause of which is independent of, and more general than these functions, since all the parts of the fungus, its entire substance, throws forth at one time, or at successive times, light. From these experiments Tulasne infers that the same agents, oxygen, water, and warmth, are perfectly necessary to the production of phosph.o.r.escence as much in living organized beings as in those which have ceased to live. In either case, the luminous phenomena accompany a chemical reaction which consists princ.i.p.ally in a combination of the organized matter with the oxygen of the air; that is to say, in its combustion, and in the discharge of carbonic acid which thus shows itself."

We have quoted at considerable length from these observations of Tulasne on the Agaric of the olive, as they serve very much to ill.u.s.trate similar manifestations in other species, which doubtless resemble each other in their main features.

Mr. Gardner has graphically described his first acquaintance in Brazil with the phosph.o.r.escent species which now bears his name. It was encountered on a dark night of December, while pa.s.sing through the streets of Villa de Natividate. Some boys were amusing themselves with some luminous object, which at first he supposed to be a kind of large fire-fly, but on making inquiry he found it to be a beautiful phosph.o.r.escent Agaric, which he was told grew abundantly in the neighbourhood on the decaying fronds of a dwarf palm. The whole plant gives out at night a bright light somewhat similar to that emitted by the larger fire-flies, having a pale greenish hue. From this circ.u.mstance, and from growing on a palm, it was called by the inhabitants "flor de coco."[C]

The number of recognized phosph.o.r.escent species of _Agaricus_ is not large, although two or three others may be enumerated in addition to those cited by Tulasne. Of these, _Agaricus lampas_, and some others, are found in Australia.[D] In addition to the _Agaricus noctileucus_, discovered by Gaudichaud, and the _Agaricus igneus_ of Rumphius, found in Amboyna, Dr. Hooker speaks of the phenomenon as common in Sikkim, but he seems never to have been able to ascertain with what species it was a.s.sociated.

Dr. Cuthbert Collingwood has communicated some further information relative to the luminosity of a species of _Agaricus_ in Borneo (supposed to be _A. Gardneri_), in which he says, "The night being dark, the fungi could be very distinctly seen, though not at any great distance, shining with a soft pale greenish light. Here and there spots of much more intense light were visible, and these proved to be very young and minute specimens. The older specimens may more properly be described as possessing a greenish luminous glow, like the glow of the electric discharge, which, however, was quite sufficient to define its shape, and, when closely examined, the chief details of its form and appearance. The luminosity did not impart itself to the hand, and did not appear to be affected by the separation from the root on which it grew, at least not for some hours. I think it probable that the mycelium of this fungus is also luminous, for, upon turning up the ground in search of small luminous worms, minute spots of light were observed, which could not be referred to any particular object or body when brought to the light and examined, and were probably due to some minute portions of its mycelium."[E] The same writer also adds, "Mr.

Hugh Low has a.s.sured me that he saw the jungle all in a blaze of light (by which he could see to read) as, some years ago, he was riding across the island by the jungle road; and that this luminosity was produced by an Agaric."

Similar experiences were detailed by Mr. James Drummond in a letter from Swan River, in which two species of Agaric are concerned. They grew on the stumps of trees, and had nothing remarkable in their appearance by day, but by night emitted a most curious light, such as the writer never saw described in any book. One species was found growing on the stump of a _Banksia_ in Western Australia. The stump was at the time surrounded by water. It was on a dark night, when pa.s.sing, that the curious light was first observed. When the fungus was laid on a newspaper, it emitted by night a phosph.o.r.escent light, enabling persons to read the words around it, and it continued to do so for several nights with gradually decreasing intensity as the plant dried up. In the other instance, which occurred some years after, the author, during one of his botanical trips, was struck by the appearance of a large Agaric, measuring sixteen inches in diameter, and weighing about five pounds. This specimen was hung up to dry in the sitting-room, and on pa.s.sing through the apartment in the dark it was observed to give out the same remarkable light. The luminous property continued, though gradually diminishing, for four or five nights, when it ceased on the plant becoming dry. "We called some of the natives," he adds, "and showed them this fungus when emitting light, and the poor creatures cried out 'chinga,' their name for a spirit, and seemed much afraid of it."[F]

Although the examples already cited are those of species of Agaric, luminosity is not by any means wholly confined to that genus. Mr.

Worthington Smith has recorded his experiences of some specimens of the common _Polyporus annosus_ which were found on some timbers in the Cardiff coal mines. He remarks that the colliers are well acquainted with phosph.o.r.escent fungi, and the men state that sufficient light is given "to see their hands by." The specimens of _Polyporus_ were so luminous that they could be seen in the dark at a distance of twenty yards. He observes further, that he has met with specimens of _Polyporus sulfureus_ which were phosph.o.r.escent. Some of the fungi found in mines, which emit light familiar to the miners, belong to the incomplete genus _Rhizomorpha_, of which Humboldt amongst others gives a glowing account. Tulasne has also investigated this phenomenon in connection with the common _Rhizomorpha subterranea_, Pers. This species extends underneath the soil in long strings, in the neighbourhood of old tree stumps, those of the oak especially, which are becoming rotten, and upon these it is fixed by one of its branches. These are cylindrical, very flexible, branching, and clothed with a hard bark, encrusting and fragile, at first smooth and brown, becoming later very rough and black. The interior tissue, at first whitish, afterwards of a more or less deep brown colour, is formed of extremely long parallel filaments from .0035 to .015 _mm._ in diameter.

On the evening of the day when I received the specimens,[G] he writes, 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 phosph.o.r.escent 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 phosph.o.r.escence. A young stalk which had been split lengthwise, and the internal substance of which was very phosph.o.r.escent, could imbibe olive oil many times and yet continue for a long time to give a feeble light. By preserving these _Rhizomorphae_ in an adequate state of humidity, I have been able for many evenings to renew the examination of their phosph.o.r.escence; 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 phosph.o.r.escence 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 phosph.o.r.escent.

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 a.s.sured 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 phosph.o.r.escent; 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 quant.i.ty 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 pa.s.s 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 sp.a.w.n 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 ma.s.s 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 phosph.o.r.escence 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 caerulescens_ 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 pa.s.sing 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 p.r.o.nouncing 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 pa.s.s 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 pa.s.sing by vinous tints into purplish black. These are the predominating gradations, but there are occasional blues and mineral greens, pa.s.sing 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 n.o.ble _Agaricus muscarius_, with its warty crimson pileus, is scarcely eclipsed by the continental orange _Agaricus caesarius_. 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 Phosph.o.r.escence 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 Linnaean Society (Botany)," vol.

x. p. 469.

[F] In "Hooker's Journal of Botany" for April, 1842.

[G] Tulasne, "Sur la Phosph.o.r.escence," 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 quant.i.ty 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 ma.s.ses 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, _Sphaeronemei_, _Melanconei_, _Torulacei_, _Dematiei_ and _Mucedines_, while some probably belonged to the _Pucciniaei_ and _Caeomacei_.

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 ill.u.s.trated, 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 cla.s.sification amongst the higher plants, should be introduced as an element of cla.s.sification in one of the largest genera of fungi.

[Ill.u.s.tration: FIG. 45.--Spores of (_a_) _Agaricus mucidus_; (_b_) _Agaricus v.a.g.i.n.atus_; (_c_) _Agaricus pascuus_; (_d_) _Agaricus nidorosus_; (_e_) _Agaricus campestris_. (Smith.)]

[Ill.u.s.tration: 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_.

[Ill.u.s.tration: FIG. 46a.--(_a_) Spore of _Gomphidius viscidus;_ (_b_) spore of _Coprinus micaceus_.]

[Ill.u.s.tration: FIG. 47.--Spores of (_a_) _Polyporus caesius_; (_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 ill.u.s.trate 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 s.p.a.ce, 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 sporoph.o.r.es; 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 _Hepaticae_, 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; a.n.a.logy 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]