It commonly happens that one of the first inquiries which the student seeks to have answered, after an interest is excited in fungi, is—Where, and under what circumstances, are they to be found? The inexperienced, indeed, require some guide, or much labour will be expended and patience lost in seeking microscopic forms in just such places as they are least likely to inhabit. Nor is it wholly unprofitable or uninteresting for others, who do not claim to be students, to summarize the habitats of these organisms, and learn how much the circumstances of their immediate surrounding elements influence production. For reasons which will at once be recognized by the mycologist, the most satisfactory method of study will be somewhat that of the natural groups into which fungi are divided.

Agaricini.—There is such a close affinity between all the genera of this group that it will be a manifest advantage to take together all those fleshy pileate fungi, the fruit of which is borne on folded plates or gills. It must be premised of this group that, for the majority, shade, a moderate amount of moisture, and steady warmth, but not too great heat, are required. A stroll through a wood in autumn will afford good evidence of the predilection of Agaricini, as well as some smaller groups, for such spots. A larger proportion will be found in woods, where shade is afforded, than on open heaths or pastures. These wood-loving forms will consist, again, of those which appear on the soil, and those which are found on rotten stumps and decaying trees. Many of those which grow on trees have a lateral stem, or scarcely any stem at all. It may be remarked, that some species which spring from the soil delight most in the shelter of particular trees. The Agarics of a beech wood will materially differ largely from those in an oak wood, and both will differ from those which spring up beneath coniferous trees.

It may be accepted as true of the largest proportion of terrestrial species, that if they do not spring directly from rotten leaves, and vegetable dÉbris in the last stage of decay, the soil will be rich in vegetable humus. A few only occur on sandy spots. The genus Marasmius is much addicted to dead leaves; Russula, to open places in woods, springing immediately from the soil. Lactarius prefers trees, and when found in exposed situations, occurs mostly under the shadow of trees.[A] Cantharellus, again, is a woodland genus, many of the species loving to grow amongst grass or moss, and some as parasites on the latter. Coprinus is not a genus much addicted to woods, but is rather peculiar in its attachment to man—if such expression, or one even implying domesticity, might be employed—farmyards, gardens, dunghills, the base of old gateposts and railings, in cellars, on plaster walls, and even on old damp carpets. Hygrophorus loves “the open,” whether pastures, lawns, heaths, commons, or up the slopes of mountains, nearly to the top of the highest found in Great Britain. Cortinarius seems to have a preference for woods, whilst Bolbitius affects dung, or a rich soil. Lentinus, Panus, Lenzites, and Schizophyllum all grow on wood. Coming to the subgenera of Agaricus, we find Pleurotus, Crepidotus, Pluteus, Collybia, Pholiota, Flammula, Hypholoma, and some species of Psathyra growing on wood, old stumps, or charcoal; Amanita, Tricholoma, and Hebeloma most attached to woods; Clitocybe and Mycena chiefly amongst leaves; Nolanea amongst grass; Omphalia and Galera chiefly in swampy places; Lepiota, Leptonia, Psalliota, Stropharia, Psilocybe, and Psathyrella mostly in open places and pastures; Deconica and PanÆolus mostly on dung; Entoloma and Clitopilus chiefly terrestrial, and the rest variable.

Of special habitats, we may allude to Nyctalis, of which the species are parasitic on dead fungi belonging to the genus Russula. One or two species of Agaricus, such as Agaricus tuberosus and Agaricus racemosus, P., grow on decaying Agarics, whilst Agaricus Loveianus flourishes on Agaricus nebularis even before it is thoroughly decayed. A few species grow on dead fir cones, others on old ferns, &c. Agaricus cepoestipes, Sow., probably of exotic origin, grows on old tan in hothouses. Agaricus caulicinalis, Bull, flourishes on old thatch, as well as twigs, &c. Agaricus juncicola, Fr., affects dead rushes in boggy places, whilst Agaricus affricatus, Fr., and Agaricus sphagnicola, B., are attached to bog moss in similar localities. Some few species are almost confined to the stems of herbaceous plants. Agaricus petasatus, Fr., Agaricus cucumis, P., and Paxillus panuoides, F., have a preference for sawdust. Agaricus carpophilus, Fr., and Agaricus balaninus, P., have a predilection for beech mast. Agaricus urticoecola, B. and Br., seems to confine itself to nettle roots. Coprinus radians, Fr., makes its appearance on plaster walls, Coprinus domesticus, Fr., on damp carpets. The only epizoic species, according to M. Fries, is Agaricus cerussatus v. nauseosus, which has been met with in Russia on the carcase of a wolf; this, however, might have been accidental. Persoon described Agaricus Neapolitanus, which was found growing on coffee-grounds at Naples; and more recently Viviani has described another species, Agaricus CoffeÆ, with rose-coloured spores, found on old fermenting coffee-grounds at Genoa.[B] Tratinnick figures a species named Agaricus Markii, which was found in wine casks in Austria. A Coprinus has, both in this country and on the Continent, been found, after a very short time, on the dressing of wounds, where there has been no neglect. A curious case of this kind, which at the time excited great interest, occurred some fifty years since at St. George’s Hospital. Some species appear to confine themselves to particular trees, some to come up by preference on soil in garden pots. Certain species have a solitary, others a gregarious habit, and, of the latter, Agaricus grammopodius, Bull, Agaricus gambosus, Fr., Marasmius oreades, Fr., and some others grow in rings. Hence it will be seen that, within certain limits, there is considerable variation in the habitats of the Agaricini.

Boleti do not differ much from Agaricini in their localization. They seem to prefer woods or borders of woods to pastures, seldom being found in the latter. One species, B. parasiticus, Bull, grows on old specimens of Scleroderma, otherwise they are for the most part terrestrial.

Polypori also have no wide range of habitat, except in choice of trees on which to grow, for the majority of them are corticolous. The section Mesopus, which has a distinct central stem, has some species which prefer the ground. Polyporus tuberaster, P., in Italy springs from the Pietra funghaia,[C] and is cultivated for food as well as Polyporus avellanus, which is reared from charred blocks of cob-nut trees.

In other genera of the Polyporei similar habitats prevail. Merulius lacrymans, Fr., one form of dry rot, occurs in cellars, and too often on worked timber; whilst Merulius himantoides, Fr., is much more delicate, sometimes running over plants in conservatories.

Hydnei.—There is nothing calling for special note on the habitats of these fungi. The stipitate species of Hydnum are some of them found in woods, others on heaths, one on fir-cones, while the rest have similar habitats to the species of Polyporus.

Auricularini.—The genera Hymenochoete, Stereum, and Corticium, with some species of Thelephora, run over corticated or decorticated wood; other species of Thelephora grow on the ground. The Pezizoid forms of Cyphella and Solenia, like species of Peziza, sometimes occur on bark, and of the former genus some on grasses and others on moss.

Clavariei.—The interesting, often brightly-coloured, tufts of Clavaria are usually found amongst grass, growing directly from the ground. Only in rare instances do they occur on dead leaves or herbaceous stems. Calocera probably should be classed with the Tremellini, to which its structure seems more closely allied. The species are developed on wood. The species of Typhula and Pistillaria are small, growing chiefly on dead herbaceous plants. One or two are developed from a kind of Sclerotium, which is in fact a compact perennial mycelium.

Tremellini.—These curious gelatinous fungi are, with rare exceptions, developed on branches or naked wood; Tremella versicolor, B. and Br., one of the exceptions, being parasitic on a species of Corticium, and Tremella epigÆa, B. and Br., spreading over the naked soil. This completes our rapid survey of the habitats of the Hymenomycetes. Very few of them are really destructive to vegetation, for the Agarics and Polypori found on growing trees are seldom to be seen on vigorous, but rather on dead branches or partly-decayed trunks.

The Gasteromycetes are far less numerous in species, and also in individuals, but their habitats are probably more variable. The HypogÆi, or subterranean species, are found either near the surface or buried in the soil, usually in the neighbourhood of trees.

Phalloidei.—In most cases the species prefer woody places. They are mostly terrestrial, and have the faculty of making their presence known, even when not seen, by the fetid odour which many of them exhale. Some of them occur in sandy spots.

Podaxinei.—These resemble in their localities the Trichogastres. Species of Podaxon affect the nests of Termites in tropical countries.[D] Others are found growing amongst grass.

Trichogastres.—These are chiefly terrestrial. The rare but curious Batarrea phalloides, P., has been found on sand-hills, and in hollow trees. Tulostoma mammosum, Fr., occurs on old stone walls, growing amongst moss. Geaster striatus, D. C., was at one time usually found on the sand of the Denes at Great Yarmouth. Although Lycoperdon giganteum, Batsch, occurs most frequently in pastures, or on hedge banks in fields, we have known it to occur annually for some consecutive years in a garden near London. The species of Scleroderma seem to prefer a sandy soil. Agloeocystis is rather an anomalous genus, occurring on the fruit heads of Cyperus, in India. Broomeia occurs at the Cape on rotten wood.

Myxogastres.—Rotten wood is one of the most favoured of matrices on which these fungi develop themselves; some of them, however, are terrestrial. Æthalium will grow on spent tan and other substances. Species of Diderma flourish on mosses, jungermanniÆ, grass, dead leaves, ferns, &c. Angioridium sinuosum, Grev., will run over growing plants of different kinds, and Spumaria, in like manner, encrusts living grasses. Badhamia not only flourishes on dead wood, but one species is found on the fading leaves of coltsfoot which are still green. Craterium runs over almost any substance which lies in its way. Licea perreptans was found in a cucumber frame heated with spent hops. One or two Myxogastres have been found on lead, or even on iron which had been recently heated. Sowerby found one on cinders, in one of the galleries of St. Paul’s Cathedral.

Nidulariacei grow on the ground, or on sticks, twigs, chips, and other vegetable substances, such as sawdust, dung, and rotten wood.

The Coniomycetes consist of two sections, which are based on their habitats. In one section the species are developed on dead or dying plants, in the other they are parasitic on living plants. The former includes the SphÆronemei, which are variable in their proclivities, although mostly preferring dead herbaceous plants and the twigs of trees. The exceptions are in favour of SphÆronema, some of which are developed upon decaying fungi. In the large genera, Septoria, Ascochyta, Phyllosticta, Asteroma, &c., the favourite habitat is fading and dying leaves of plants of all kinds. In the majority of cases these fungi are not autonomous, but are merely the stylosporous conditions of SphÆria. They are mostly minute, and the stylospores are of the simplest kind. The Melanconiei have a preference for the twigs of trees, bursting through the bark, and expelling the spores in a gelatinous mass. A few of them are foliicolous, but the exceptions are comparatively rare, and are represented chiefly in Gloeosporium, species of which are found also on apples, peaches, nectarines, and other fruits. The Torulacei are superficial, having much of the external appearance of the black moulds, and like them are found on decaying vegetable substances, old stems of herbaceous plants, dead twigs, wood, stumps of trees, &c. The exceptions are in favour of such species as Torula sporendonema, which is the red mould of cheese, and also occurs on rats’ dung, old glue, &c., and Sporendonema MuscÆ, which is only the conidia of a species of Achlya. One species of Bactridium is parasitic on the hymenium of Peziza, and Echinobotryum atrum, on the flocci of black moulds.

In the other section of Coniomycetes the species are parasitic upon, and destructive to, living plants, very seldom being found on really dead substances, and even in such rare cases undoubtedly developed during the life of the tissues. Mostly the ultimate stage of these parasites is exhibited in the ruptured cuticle, and the dispersion of the dust-like spores; but in Tilletia caries, Thecaphora hyalina, and Puccinia incarcerata, they remain enclosed within the fruit of the foster-plant. The different genera exhibit in some instances a liking for plants of certain orders on which to develop themselves. Peridermium attacks the ConiferÆ; Gymnosporangium and Podisoma the different species of Juniper; Melampsora chiefly the leaves of deciduous trees; Roestelia attaches itself to pomaceous trees, whilst Graphiola affects the PalmaceÆ, and Endophyllum the succulent leaves of houseleek. In Æcidium a few orders seem to be more liable to attack than others, as the CompositÆ, RanunculaceÆ, LeguminosÆ, LabiatÆ, &c., whilst others, as the GraminaceÆ, EricaceÆ, MalvaceÆ, CruciferÆ, are exempt. There are, nevertheless, very few natural orders of phanerogamous plants in which some one or more species, belonging to this section of the Coniomycetes, may not be found; and the same foster-plant will occasionally nurture several forms. Recent investigations tend to confirm the distinct specific characters of the species found on different plants, and to prove that the parasite of one host will not vegetate upon another, however closely allied. This admission must not, however, be accepted as universally applicable, and therefore it should not be assumed, because a certain parasite is found developed on a special host, that it is distinct, unless distinctive characters, apart from habitat, can be detected. Æcidium compositarum and Æcidium ranunculacearum, for instance, are found on various composite and ranunculaceous plants, and as yet no sufficient evidence has been adduced to prove that the different forms are other than varieties of one of the two species. On the other hand, it is not improbable that two species of Æcidium are developed on the common berberry, as De Bary has indicated that two species of mildew, Puccinia graminis, and Puccinia straminis, are found on wheat.

Hyphomycetes.—The moulds are much more universal in their habitats, especially the Mucedines. The Isariacei have a predilection for animal substances, though not exclusively. Some species occur on dead insects, others on decaying fungi, and the rest on sticks, stems, and rotten wood. The Stilbacei have also similar habitats, except that the species of Illosporium seem to be confined to parasitism on lichens. The black moulds, Dematiei, are widely diffused, appearing on herbaceous stems, twigs, bark, and wood in most cases, but also on old linen, paper, millboard, dung, rotting fruit, &c., whilst forms of Cladosporium and Macrosporium are met with on almost every kind of vegetable substance in which the process of decay has commenced.

Mucedines, in some instances, have not been known to appear on more than one kind of matrix, but in the far greater number of cases they nourish on different substances. Aspergillus glaucus and Penicillium crustaceum are examples of these universal Mucedines. It would be far more difficult to mention substances on which these moulds are never developed than to indicate where they have been found. With the species of Peronospora it is different, for these are truly parasitic on living plants, and, as far as already known, the species are confined to certain special plants, and cannot be made to vegetate on any other. The species which causes the potato murrain, although liable to attack the tomato, and other species of SolanaceÆ, does not extend its ravages beyond that natural order, whilst Peronospora parasitica confines itself to cruciferous plants. One species is restricted to the UmbelliferÆ, another, or perhaps two, to the LeguminosÆ, another to RubiaceÆ, two or three to RanunculaceÆ, and two or three to CaryophyllaceÆ. All the experiments made by De Bary seem to prove that the species of Peronospora will only flourish on certain favoured plants, to the exclusion of all others. The non-parasitic moulds are scarcely exclusive. In Oidium some species are parasitic, but probably all the parasitic forms are states of Erysiphe, the non-parasitic alone being autonomous; of these one occurs on Porrigo lupinosa, others on putrefying oranges, pears, apples, plums, &c., and one on honeycomb. Acrospeira grows in the interior of sweet chestnuts, and we have seen a species growing within the hard testa of the seeds of Guilandina Bondue, from India, to which there was no external opening visible, and which was broken with considerable difficulty. Several Mucedines are developed on the dung of various animals, and seldom on anything else.

The Physomycetes consist of two orders, Antennariei and Mucorini, which differ from each other almost as much in habitat as in external appearance. The former, if represented by Antennaria, runs over the green and fading leaves of plants, forming a dense black stratum, like a congested layer of soot; or in Zasmidium, the common cellar fungus, runs over the walls, bottles, corks, and other substances, like a thick sooty felt. In the Mucorini, as in the Mucedines, there is usually less restriction to any special substance. Mucor mucedo occurs on bread, paste, preserves, and various substances; other species of Mucor seem to have a preference for dung, and some for decaying fungi, but rotting fruits are nearly sure to support one or other of the species. The two known species of the curious genus Pilobolus, as well as Hydrophora, are confined to dung. Sporodinia, Syzygites, &c., nourish on rotten Agarics, where they pass through their somewhat complicated existence.

The Ascomycetes contain an immense number of species, and in general terms we might say that they are found everywhere. The Tuberacei are subterraneous, with a preference for calcareous districts. The Perisporiacei are partly parasitical and partly not. The Erysiphei include those of the former which flourish at the expense of the green parts of roses, hops, maples, poplars, peas, and many other plants, both in Europe and in North America, whilst in warmer latitudes the genus Meliola appears to take their place.

The Elvellacei are fleshy fungi, of which the larger forms are terrestrial; Morchella, Gyromitra, and Helvella mostly growing in woods, Mitrula, Spathularia, and Leotia in swampy places, and Geoglossum amongst grass. The very large genus Peziza is divided into groups, of which AleuriÆ are mostly terrestrial. This group includes nearly all the large-sized species, although a few belong to the next. LachneÆ are partly terrestrial and partly epiphytal, the most minute species being found on twigs and leaves of dead plants. In Phialea the species are nearly entirely epiphytal, as is also the case in Helotium and allied genera. Some species of Peziza are developed from the curious masses of compact mycelium called Sclerotia. A few are rather eccentric in their habitats. P. viridaria, P. domestica, and P. hoemastigma, grow on damp walls; P. granulata and some others on dung. Peziza Bullii was found growing on a cistern. P. theleboloides appears in profusion on spent hops. P. episphÆria, P. clavariarum, P. vulgaris, Helotium pruinosum, and others are parasitic on old fungi. One or two species of Helotium grow on submerged sticks, so as to be almost aquatic, a circumstance of rare occurrence in fungi. Other Discomycetes are similar in their habitats to the Elvellacei. The group to which the old genus Ascobolus belongs is in a great measure confined to the dung of various animals, although there are two or three lignicolous species; and Ascophanus saccharinus was first found on old leather, Ascophanus testaceus on old sacking, &c. Ascomyces is, perhaps, the lowest form which ascomycetous fungi assume, and the species are parasitic on growing plants, distorting the leaves and fruit, constituting themselves pests to the cultivators of peach, pear, and plum trees.

The SphÆriacei include a very large number of species which grow on rotten wood, bark, sticks, and twigs; another group is developed on dead herbaceous stems; yet another is confined to dead or dying leaves. One genus, Torrubia, grows chiefly on insects; Hypomyces is parasitic on dead fungi; Claviceps is developed from ergot, Poronia on dung, Polystigma on living leaves, as well as some species of Stigmatea and Dothidea. Of the genus SphÆria, a considerable number are found on dung, now included by some authors under Sordaria and Sporormia, genera founded, as we think, on insufficient characters. A limited number of species are parasitic on lichens, and one species only is known to be aquatic.

We have thus rapidly, briefly, and casually indicated the habitats to which the majority of the larger groups of fungi are attached, regarding them from a systematic point of view. There is, however, another aspect from which we might approach the subject, taking the host or matrix, or in fact the habitat, as the basis, and endeavouring to ascertain what species of fungi are to be found in such positions. This has partly been done by M. Westendorp;[E] but every year adds considerably to the number of species, and what might have been moderately accurate twelve years since can scarcely be so now. To carry this out fully a special work would be necessary, so that we shall be content to indicate or suggest, by means of a few illustrations, the forms of fungi, often widely distinct in structure and character, to be found in the same locality.

The stems of herbaceous plants are favourite habitats for minute fungi. The old stems of the common nettle, for example, perform the office of host to about thirty species.[F] Of these about nine are PezizÆ, and there are as many sphÆriaceous fungi, whilst three species of Dendryphium, besides other moulds, select this plant. Some of these have not hitherto been detected growing on any other stems, such as SphÆria urticÆ and Lophiostoma sex-nucleatum, to which we might add Peziza fusarioides and Dendryphium griseum. These do not, however, include the whole of the fungi found on the nettle, since others are parasitic upon its living green parts. Of these may be named Æcidium urticÆ and Peronospora urticÆ, as well as two species described by DesmaziÈres as Fusisporium urticÆ and Septoria urticÆ. Hence it will be seen how large a number of fungi may attach themselves to one herbaceous plant, sometimes whilst living, but most extensively when dead. This is by no means a solitary instance, but a type of what takes place in many others. If, on the other hand, we select such a tree as the common lime, we shall find that the leaves, twigs, branches, and wood bear, according to M. Westendorp,[G] no less than seventy-four species of fungi, and of these eleven occur on the leaves. The spruce fir, according to the same authority, nourishes one hundred and fourteen species, and the oak not less than two hundred.

It is curious to note how fungi are parasitic upon each other in some instances, as in that of Hypomyces, characteristic of the genus, in which sphÆriaceous fungi make hosts of dead Lactarii, &c. We have already alluded to Nyctalis, growing on decayed RussulÆ, to Boletus parasiticus, flourishing on old Scleroderma, and to Agaricus Loveianus, on the pileus of Agaricus nebularis. To these we may add Torrubia ophioglossoides and T. capitata, which flourish on decaying Elaphomyces, Stilbum tomentosum on old Trichia, Peziza Clavariarum on dead Clavaria, and many others, the mere enumeration of which would scarcely prove interesting. A very curious little parasite was found by Messrs. Berkeley and Broome, and named by them Hypocrea inclusa, which makes itself a home in the interior of truffles. Mucors and moulds flourish on dead and decaying Agarics, and other fleshy forms, in great luxuriance and profusion. Mucor ramosus is common on Boletus luridus, and Syzygites megalocarpus on Agarics, as well as Acrostalagmus cinnabarinus. A very curious little parasite, Echinobotryum atrum, occurs like minute nodules on the flocci of black moulds. Bactridium HelvellÆ usurps the fructifying disc of species of Peziza. A small Sphinctrina is found both in Britain and the United States on old Polypori. In SphÆria nigerrima, Nectria episphÆria, and two or three others, we have examples of one sphÆriaceous fungus growing upon another.

Mr. Phillips has recently indicated the species of fungi found by him on charcoal beds in Shropshire,[H] but, useful as it is, that only refers to one locality. A complete list of all the fungi which have been found growing on charcoal beds, burnt soil, or charred wood, would be rather extensive. The fungi found in hothouses and stoves are also numerous, and often of considerable interest from the fact that they have many of them never been found elsewhere. Those found in Britain,[I] for instance, are excluded from the British Flora as doubtful, because, growing upon or with exotic plants, they are deemed to be of exotic origin, yet in very few cases are they known to be inhabitants of any foreign country. Some species found in such localities are not confined to them, as Agaricus coepestipes, Agaricus cristatus, Æthalium vaporarium, &c. It is somewhat singular that certain species have a predilection for growing in proximity with other plants with which they do not appear to have any more intimate relation. Truffles, for instance, in association with oaks, Peziza lanuginosa under cedar-trees, Hydnangium carneum about the roots of Eucalypti, and numerous species of Agaricini, which are only found under trees of a particular kind. As might be anticipated, there is no more fertile habitat for fungi than the dung of animals, and yet the kinds found in such locations belong to but a few groups. Amongst the Discomycetes, a limited number of the genus Peziza are fimicolous, but the allied genus Ascobolus, and its own immediate allies, include amongst its species a large majority that are found on dung. If we take the number of species at sixty-four, there are only seven or eight which do not occur on dung, whilst fifty-six are fimicolous. The species of SphÆria which are found on the same substances are also closely allied, and some Continental authors have grouped them under the two proposed genera Sporormia and Sordaria, whilst Fuckel[J] proposes a distinct group of SphÆriacei, under the name of Fimicoli, in which he includes as genera Coprolepa, Hypocopra, Delitschia, Sporormia, Pleophragmia, Malinvernia, Sordaria, and Cercophora. The two species of Pilobolus, and some of Mucor, are also found on dung, Isaria felina on that of cats, Stilbum fimetarium and a few other moulds, and amongst Agarics some species of Coprinus. Animal substances are not, as a rule, prolific in the production of fungi. Ascobolus saccharinus and one or two others have been found upon old leather. Onygena of two or three species occurs on old horn, hoofs, &c. Cheese, milk, &c., afford a few forms, but the largest number infest dead insects, either under the mouldy form of Isaria or the more perfect condition of Torrubia, and occasionally under other forms.

Robin[K] has recorded that three species of Brachinus, of the order Coleoptera, have been found infected, whilst living, with a minute yellow fungus which he calls Laboulbenia Rougeti, and the same species has been noted on other beetles. Torrubia MelolonthÆ[L] has been described by Tulasne as occurring on the maybug or cockchafer, which is allied to, if not identical with, Cordyceps Ravenelii, B. and C., and also that described and figured by M. Fougeroux de Bondaroy.[M] Torrubia curculionum, Tul., occurs on several species of beetles, and seems to be by no means uncommon in Brazil and Central America. Torrubia coespitosa, Tul., which may be the same as Cordyceps Sinclairi, B.,[N] is found on the larvÆ of Orthoptera in New Zealand, Torrubia Miquelii on the larvÆ of Cicada in Brazil, and Torrubia sobolifera on the pupÆ of Cicada in the West Indies. A romantic account is given of this in an extract cited by Dr. Watson in his communication to the Royal Society.[O] “The vegetable fly is found in the island Dominica, and (excepting that it has no wings) resembles the drone, both in size and colour, more than any other English insect. In the month of May it buries itself in the earth and begins to vegetate. By the latter end of July, the tree is arrived at its full growth, and resembles a coral branch, and is about three inches high, and bears several little pods, which, dropping off, become worms, and from thence flies, like the English caterpillar.” Torrubia Taylori, which grows from the caterpillar of a large moth in Australia, is one of the finest examples of the genus. Torrubia Robertsii, from New Zealand, has long been known as attacking the larva of Hepialus virescens. There are several other species on larvÆ of different insects, on spiders, ants, wasps, &c., and one or two on mature Lepidoptera, but the latter seem to be rare.

That fungi should make their appearance and flourish in localities and conditions generally considered inimical to vegetable life is no less strange than true. We have already alluded to the occurrence of some species on spent tan, and some others have been found in locations as strange. We have seen a yellow mould resembling Sporotrichum in the heart of a ball of opium, also a white mould appears on the same substance, and more than one species is troublesome in the opium factories of India. A mould made its appearance some years since in a copper solution employed for electrotyping in the Survey Department of the United States,[P] decomposing the salt, and precipitating the copper. Other organisms have appeared from time to time in various inorganic solutions, some of which were considered destructive to vegetable life, and it is not improbable that some of these organisms were low conditions of mould. It may well occasion some surprise that fungi should be found growing within cavities wholly excluded from the external air, as in the hollow of filberts, and the harder shelled nuts of Guilandina, in the cavities of the fruit of tomato, or in the interior of an egg. It is scarcely less extraordinary that Hypocrea inclusa should flourish in the interior of a kind of truffle.

From the above it will be concluded that the habitats of fungi are exceedingly variable, that they may be regarded as almost universal wherever decaying vegetable matter is found, and that under some conditions animal substances, especially of vegetable feeders, such as insects, furnish a pabulum for their development.

A very curious and interesting inquiry presents itself to our minds, which is intimately related to this subject of the habitats of fungi. It shapes itself into a sort of “puzzle for the curious,” but at the same time one not unprofitable to think about. How is the occurrence of new and before unknown forms to be accounted for in a case like the following?[Q]

It was our fortune—good fortune as far as this investigation was concerned—to have a portion of wall in our dwelling persistently damp for some months. It was close to a cistern which had become leaky. The wall was papered with “marbled” paper, and varnished. At first there was for some time nothing worthy of observation, except a damp wall—decidedly damp, discoloured, but not by any means mouldy. At length, and rather suddenly, patches of mould, sometimes two or three inches in diameter, made their appearance. These were at first of a snowy whiteness, cottony and dense, just like large tufts of cotton wool, of considerable expansion, but of miniature elevation. They projected from the paper scarcely a quarter of an inch. In the course of a few weeks the colour of the tufts became less pure, tinged with an ochraceous hue, and resembling wool rather than cotton, less beautiful to the naked eye, or under a lens, and more entangled. Soon after this darker patches made their appearance, smaller, dark olive, and mixed with, or close to, the woolly tufts; and ultimately similar spots of a dendritic character either succeeded the olive patches, or were independently formed. Finally, little black balls, like small pin heads, or grains of gunpowder, were found scattered about the damp spots. All this mouldy forest was more than six months under constant observation, and during that period was held sacred from the disturbing influences of the housemaid’s broom and duster.

Curiosity prompted us from the first to submit the mouldy denizens of the wall to the microscope, and this curiosity was increased week by week, on finding that none of the forms found vegetating on nearly two square yards of damp wall could be recognized as agreeing specifically with any described moulds with which we were acquainted. Here was a problem to be solved under the most favourable conditions, a forest of mould indoors, within a few yards of the fireside, growing quite naturally, and all strangers. Whence could these new forms proceed?

The cottony tufts of white mould, which were the first to appear, had an abundant mycelium, but the erect threads which sprang from this were for a long time sterile, and closely interlaced. At length fertile threads were developed in tufts, mixed with the sterile threads. These fruit-bearers were shorter and stouter, more sparingly branched, but beset throughout nearly their whole length with short patent, alternate branchlets. These latter were broadest towards the apex, so as to be almost clavate, and the extremity was beset with two or three short spicules. Each spicule was normally surmounted by an obovate spore. The presence of fertile threads imparted the ochraceous tint above alluded to. This tint was slight, and perhaps would not have been noticed, but from the close proximity of the snow-white tufts of barren threads. The fertile flocci were decumbent, probably from the weight of the spores, and the tufts were a little elevated above the surface of the matrix. This mould belonged clearly to the Mucedines, but it hardly accorded well with any known genus, although most intimately related to Rhinotrichum, in which it was placed as Rhinotrichum lanosum.[R]

The white mould having become established for a week or two, small blackish spots made their appearance on the paper, sometimes amongst thin patches of the mould, and sometimes outside them. These spots, at first cloudy and indefinite, varied in size, but were usually less than a quarter of an inch in diameter. The varnish of the paper was afterwards pushed off in little translucent flakes or scales, an erect olivaceous mould appeared, and the patches extended to nearly an inch in diameter, maintaining an almost universal circular form. This new mould sometimes possessed a dirty reddish tint, but was commonly dark olive. There could be no mistake about the genus to which this mould belonged; it had all the essential characters of Penicillium. Erect jointed threads, branched in the upper portion in a fasciculate manner, and bearing long beaded threads of spores, which formed a tassel-like head, at the apex of each fertile thread. Although at first reminded of Penicillium olivaceum, of Corda, by the colour of this species, it was found to differ in the spores being oblong instead of globose, and the ramifications of the flocci were different. Unable again to find a described species of Penicillium with which this new mould would agree, it was described under the name of Penicillium chartarum.[S]

Almost simultaneously, or but shortly after the perfection of the spores of Penicillium, other and very similar patches appeared, distinguished by the naked eye more particularly by their dendritic form. This peculiarity seemed to result from the dwarfed habit of the third fungus, since the varnish, though cracked and raised, was not cast off, but remained in small angular fragments, giving to the spots their dendritic appearance, the dark spores of the fungus protruding through the fissures. This same mould was also found in many cases growing in the same spots amongst Penicillium chartarum, but whether from the same mycelium could not be determined.

The distinguishing features of this fungus consist in an extensive mycelium of delicate threads, from which arise numerous erect branches, bearing at the apex dark brown opaque spores. Sometimes the branches were again shortly branched, but in the majority of instances were single. The septate spores had from two to four divisions, many of them divided again by cross septa in the longitudinal direction of the spore, so as to impart a muriform appearance. As far as the structure and appearance of the spores are concerned, they resembled those of Sporidesmium polymorphum, under which name specimens were at first published,[T] but this determination was not satisfactory. The mycelium and erect threads are much too highly developed for a good species of Sporidesmium, although the name of Sporidesmium alternaria was afterwards adopted. In fresh specimens of this fungus, when seen in situ by a half-inch objective, the spores appear to be moniliform, but if so, all attempts to see them so connected, when separated from the matrix, failed. On one occasion, a very immature condition was examined, containing simple beaded, hyaline bodies, attached to each other by a short neck. The same appearance of beaded spores, when seen in situ, was recognized by a mycological friend, to whom specimens were submitted for confirmation.[U]

The last production which made its appearance on our wall-paper burst through the varnish as little black spheres, like grains of gunpowder. At first the varnish was elevated by pressure from beneath, then the film was broken, and the little blackish spheres appeared. These were, in the majority of cases, gregarious, but occasionally a few of the spheres appeared singly, or only two or three together. As the whole surface of the damp paper was covered by these different fungi, it was scarcely possible to regard any of them as isolated, or to declare that one was not connected with the mycelium of the others. The little spheres, when the paper was torn from the wall, were also growing from the under surface, flattened considerably by the pressure. The spherical bodies, or perithecia, were seated on a plentiful hyaline mycelium. The walls of the perithecia, rather more carbonaceous than membranaceous, are reticulated, reminding one of the conceptacles of Erysiphe, to which the perithecia bear considerable resemblance. The ostiolum is so obscure that we doubt its existence, and hence the closer affinity of the plant to the Perisporiacei than to the SphÆriacei. The interior of the perithecium is occupied by a gelatinous nucleus, consisting of elongated cylindrical asci, each enclosing eight globose hyaline sporidia, with slender branched paraphyses. A new genus has been proposed for this and another similar form, and the present species bears the name of Orbicula cyclospora.[V]

The most singular circumstance connected with this narrative is the presence together of four distinctly different species of fungi, all of them previously unknown and undescribed, and no trace amongst them of the presence of any one of the very common species, which would be supposed to develop themselves under such circumstances. It is not at all unusual for Sporocybe alternata, B., to appear in broad black patches on damp papered walls, but in this instance not a trace was to be found. What were the peculiar conditions present in this instance which led to the manifestation of four new forms, and none of the old ones? We confess that we are unable to account satisfactorily for the mystery, but, at the same time, feel equally unwilling to invent hypotheses in order to conceal our own ignorance.

These predilections must be accepted as general, to which there will be exceptions.