Part 8

Hoffmann, "Icones Analyticæ Fungorum."

De Bary, "Der Ascomyceten." Leipzic, 1863.

Berkeley, M. J., "Introduction to Cryptogamic Botany."

Seynes, J. de, "Recherches, &c., des Fistulines." Paris, 1874.

Winter, G., "Die Deutschen Sordarien." 1874.

Corda, J., "Prachtflora." Prague, 1840.

De Bary, "Über der Brandpilze." 1853.

Brefeld, O., "Botan. Untersuch. ü Schimmelpilze."

Fresenius, G., "Beiträge zur Mykologie." 1850.

Von Tieghem and Le Monnier, in "Annales des Sciences Naturelles" (1873), p. 335.

Cornu, M., "Sur les Saprolegniées," in "Ann. des Sci. Nat." 5^me sér. xv. p. 5.

Janczenski, "Sur l'Ascobolus furfuraceus," in "Ann. des Sci. Nat." 5^me sér. xv. p. 200.

De Bary and Woronin, "Beiträge zur Morphologie und Physiologie der Pilze." 1870.

Bonorden, H. F., "Abhandlungen aus dem Gebiete der Mykologie." 1864.

Coemans, E., "Spicilége Mycologique." 1862, etc.

III

CLASSIFICATION

A work of this kind could not be considered complete without some account of the systematic arrangement or classification which these plants receive at the hands of botanists. It would hardly avail to enter too minutely into details, yet sufficient should be attempted to enable the reader to comprehend the value and relations of the different groups into which fungi are divided. The arrangement generally adopted is based upon the "Systema Mycologicum" of Fries, as modified to meet the requirements of more recent microscopical researches by Berkeley in his "Introduction," and adopted in Lindley's "Vegetable Kingdom." Another arrangement was proposed by Professor de Bary, but it has never met with general acceptance.

In the arrangement to which we have alluded, all fungi are divided into two primary sections, having reference to the mode in which the fructification is produced. In one section, the spores (which occupy nearly the same position, and perform similar functions, to the seeds of higher plants) are naked; that is, they are produced on spicules, and are not enclosed in cysts or capsules. This section is called SPORIFERA, or spore-bearing, because, by general consent, the term spore is limited in fungi to such germ-cells as are not produced in cysts. The second section is termed SPORIDIIFERA, or sporidia-bearing, because in like manner the term sporidia is limited to such germ-cells as are produced in cells or cysts. These cysts are respectively known as sporangia, and asci or thecæ. The true meaning and value of these divisions will be better comprehended when we have detailed the characters of the families composing these two divisions.

First, then, the section SPORIFERA contains four families, in two of which a hymenium is present, and in two there is no proper hymenium. The term hymenium is employed to represent a more or less expanded surface, on which the fructification is produced, and is, in fact, the fruit-bearing surface. When no such surface is present, the fruit is borne on threads, proceeding direct from the root-like filaments of the mycelium, or an intermediate kind of cushion or stroma. The two families in which an hymenium is present are called Hymenomycetes and Gasteromycetes. In the former, the hymenium is exposed; in the latter, it is at first enclosed. We must examine each of these separately.

The common mushroom may be accepted, by way of illustration, as a type of the family Hymenomycetes, in which the hymenium is exposed, and is, in fact, the most noticeable feature in the family from which its name is derived. The pileus or cap bears on its under surface radiating plates or gills, consisting of the hymenium, over which are thickly scattered the basidia, each surmounted by four spicules, and on each spicule a spore. When mature, these spores fall freely upon the ground beneath, imparting to it the general colour of the spores. But it must be observed that the hymenium takes the form of gill-plates in only one order of Hymenomycetes, namely, the Agaricini; and here, as in Cantharellus, the hymenium is sometimes spread over prominent veins rather than gills. Still further divergence is manifest in the Polyporei, in which order the hymenium lines the inner surface of pores or tubes, which are normally on the under side of the pileus. Both these orders include an immense number of species, the former more or less fleshy, the latter more or less tough and leathery. There are still other forms and orders in this family, as the Hydnei, in which the hymenium clothes the surface of prickles or spines, and the Auricularini, in which the hymenium is entirely or almost even. In the two remaining orders, there is a still further divergence from the mushroom form. In the one called Clavariei, the entire fungus is either simply cylindrical or club-shaped, or it is very much branched and ramified. Whatever form the fungus assumes, the hymenium covers the whole exposed surface. In the Tremellini, a peculiar structure prevails, which at first seems to agree but little with the preceding. The whole plant is gelatinous when fresh, lobed and convolute, often brain-like, and varying in size, according to species, from that of a pin's head to that of a man's head. Threads and sporophores are imbedded in the gelatinous substance, so that the fertile threads are in reality not compacted into a true hymenium. With this introduction we may state that the technical characters of the family are thus expressed:--

Hymenium free, mostly naked, or, if enclosed at first, soon exposed; spores naked, mostly quaternate, on distinct spicules = HYMENOMYCETES.

In this family some mycologists believe that fungi attain the highest form of development of which they are capable, whilst others contend that the fructification of the Ascomycetes is more perfect, and that some of the noblest species, such as the pileate forms, are entitled to the first rank. The morel is a familiar example. Whatever may be said on this point, it is incontrovertible that the noblest and most attractive, as well as the largest, forms are classed under the Hymenomycetes.

In Gasteromycetes, the second family, a true hymenium is also present, but instead of being exposed it is for a long time enclosed in an outer peridium or sac, until the spores are fully matured, or the fungus is beginning to decay. The common puff-ball (Lycoperdon) is well known, and will illustrate the principal feature of the family. Externally there is a tough coat or peridium, which is at first pale, but ultimately becomes brown. Internally is at first a cream-coloured, then greenish, cellular mass, consisting of the sinuated hymenium and young spores, which at length, and when the spores are fully matured become brownish and dusty, the hymenium being broken up into threads, and the spores become free. In earlier stages, and before the hymenium is ruptured, the spores have been found to harmonize with those of Hymenomycetes in their mode of production, since basidia are present surmounted each by four spicules, and each spicule normally surmounted by a spore. Here is, therefore, a cellular hymenium bearing quaternary spores, but, instead of being exposed, this hymenium is wholly enclosed within an external sac or peridium, which is not ruptured until the spores are fully matured, and the hymenium is resolved into threads, together forming a pulverulent mass. It must, however, be borne in mind, that in only some of the orders composing this family is the hymenium thus evanescent, in others being more or less permanent, and this has led naturally enough to the recognition of two sub-families, in one of which the hymenium is more or less permanent, thus following the Hymenomycetous type; and in the other, the hymenium is evanescent, and the dusty mass of spores tends more towards the Coniomycetes, this being characterized as the coniospermous (or dusty-spored) sub-family.

The first sub-family includes, first of all, the Hypogæi, or subterranean species. And here again it becomes necessary to remind the reader that all subterranean fungi are not included in this order, inasmuch as some, of which the truffle is an example, are sporidiiferous, developing their sporidia in asci. To these allusion must hereafter be made. In the Hypogæi, the hymenium is permanent and convoluted, leaving numerous minute irregular cavities, in which the spores are produced on sporophores. When specimens are very old and decaying, the interior may become pulverulent or deliquescent. The structure of subterranean fungi attracted the attention of Messrs. Tulasne, and led to the production of a splendid monograph on the subject. Another order belonging to this sub-family is the Phalloidei, in which the volva or peridium is ruptured whilst the plant is still immature, and the hymenium when mature becomes deliquescent. Not only are some members of this order most singular in appearance, but they possess an odour so foetid as to be unapproached in this property by any other vegetable production. In this order, the inner stratum of the investing volva is gelatinous. When still young, and previous to the rupture of the volva, the hymenium presents sinuous cavities in which the spores are produced on spicules, after the manner of Hymenomycetes. Nidulariacei is a somewhat aberrant order, presenting a peculiar structure. The peridium consists of two or three coats, and bursts at the apex, either irregularly or in a stellate manner, or by the separation of a little lid. Within the cavity are contained one or more secondary receptacles, which are either free or attached by elastic threads to the common receptacle. Ultimately the secondary receptacles are hollow, and spores are produced in the interior, borne on spicules. The appearance in some genera as of a little bird's-nest containing eggs has furnished the name to the order.

The second sub-family contains the coniospermous puff-balls, and includes two orders, in which the most readily distinguishable feature is the cellular condition of the entire plant, in its earlier stages, in the Trichogastres, and the gelatinous condition of the early state of the Myxogastres. Both are ultimately resolved internally into a dusty mass of threads and spores. In the former, the peridium is either single or double, occasionally borne on a stem, but usually sessile. In Geaster, the "starry puff-balls," the outer peridium divides into several lobes, which fall back in a stellate manner, and expose the inner peridium, like a ball in the centre. In Polysaccum, the interior is divided into numerous cells, filled with secondary peridia. The mode of spore-production has already been alluded to in our remarks on Lycoperdon. All the species are large, as compared with those of the following sub-family, and one species of Lycoperdon attains an enormous size. One specimen recorded in the "Gardener's Chronicle" was three feet four inches in circumference, and weighed nearly ten pounds. In the Myxogastres, the early stage has been the subject of much controversy. The gelatinous condition presents phenomena so unlike anything previously recorded in plants, that one learned professor did not hesitate to propose their exclusion from the vegetable, and recognition in the animal, kingdom as associates of the Gregarines. When mature, the spores and threads so much resemble those of the Trichogastres, and the little plants themselves are so veritably miniature puff-balls, that the theory of their animal nature did not meet with a ready acceptance, and is now virtually abandoned. The characters of the family we have thus briefly reviewed are tersely stated, as--

Hymenium more or less permanently concealed, consisting in most cases of closely-packed cells, of which the fertile ones bear naked spores on distinct spicules, exposed only by the rupture or decay of the investing coat or peridium = GASTEROMYCETES.

We come now to the second section of the Sporifera, in which no definite hymenium is present. And here we find also two families, in one of which the dusty spores are the prominent feature, and hence termed Coniomycetes; the other, in which the threads are most noticeable, is Hyphomycetes. In the former of these, the reproductive system seems to preponderate so much over the vegetative, that the fungus appears to be all spores. The mycelium is often nearly obsolete, and the short pedicels so evanescent, that a rusty or sooty powder represents the mature fungus, infesting the green parts of living plants. This is more especially true of one or two orders. It will be most convenient to recognize two artificial sub-families for the purpose of illustration, in one of which the species are developed on living, and in the other on dead, plants. We will commence with the latter, recognizing first those which are developed beneath the cuticle, and then those which are superficial. Of the sub-cuticular, two orders may be named as the representatives of this group in Britain, these are the Sphæronemei, in which the spores are contained in a more or less perfect perithecium, and the Melanconiei, in which there is manifestly none. The first of these is analogous to the Sphæriacei of Ascomycetous fungi, and probably consists largely of spermogonia of known species of Sphæria, the relations of which have not hitherto been traced. The spores are produced on slender threads springing from the inner wall of the perithecium, and, when mature, are expelled from an orifice at the apex. This is the normal condition, to which there are some exceptions. In the Melanconiei, there is no true perithecium, but the spores are produced in like manner upon a kind of stroma or cushion formed from the mycelium, and, when mature, are expelled through a rupture of the cuticle beneath which they are generated, often issuing in long gelatinous tendrils. Here, again, the majority of what were formerly regarded as distinct species have been found, or suspected, to be forms of higher fungi. The Torulacei represent the superficial fungi of this family, and these consist of a more or less developed mycelium, which gives rise to fertile threads, which, by constriction and division, mature into moniliform chains of spores. The species mostly appear as blackish velvety patches or stains on the stems of herbaceous plants and on old weathered wood.