appears or is absorbed in a mucilaginous matter, which occupies its place, in the midst of which is a small nucleus, which is the rudiment of the first spore; other spores are formed consecutively, and then the substance separates into as many sections as there are sporidia. From this period each sporidium seems to have a separate existence. All have a nucleus, which is scarcely visible, often slightly granular, but which is quite distinct from the oleaginous sporidioles so frequent amongst the Discomycetes, and which are sometimes called by the same name. The sporidia are at first a little smaller than when mature, and are surrounded by mucilage. After this period the sporidia lose their nebulous granulations, whilst still preserving their nucleus; their outlines are distinct, and, amongst the true Ascobolei, commence acquiring a rosy colour, the first intimation of maturity. colour manifests itself rapidly, accumulating exclusively upon the epispore, which becomes of a deep rose, then violet, and finally violet blue, so deep as sometimes to appear quite black. There are some modifications in this coloration, since, in some species, it passes from a vinous red to grey, then to black, or from rose-violet to brown.

This

The epispore acquires a waxy consistence by this pigmentation, so that it may be detached in granules. It is to this particular consistency of the epispore that the cracks so frequent in the coloured sporidia of Ascobolus are due, through contraction of the epispore. As they approach maturity, the sporidia accumulate towards the apex of the asci, and finally escape in the manner already indicated.

In all essential particulars there is a great similarity in the structure of the other Discomycetes, especially in their reproductive system. In most of them coloured sporidia are rare. In some the receptacle is pileate, clavate, or inflated, whilst in Stictis it is very much reduced, and in the lowest form of all, Ascomyces, it is entirely absent. In the Phacidiacei, the structure is very similar to that of the Elvellacei, whilst the Hysteriacei, with greater affinities with the latter, still tend towards the Pyrenomycetes by the more horny nature of the receptacle, and the greater tendency of the hymenium to remain closed, at

least when dry. In some species of Hysterium, the sporidia are remarkably fine. M. Duby* has subjected this group to ex

amination, and M. Tulasne partly so.†

SPHÆRIACEI.—In this group there is considerable variation, within certain limits. It contains an immense number of species, and these are daily being augmented. The general feature in all is the presence of a perithecium, which contains and encloses the hymenium, and at length opening by a pore or ostiolum at the apex. In some the perithecia are simple, in others compound; in some immersed in a stroma, in others free; in some fleshy or waxy, in others carbonaceous, and in others membranaceous. But in all there is this important difference from the Ascomycetes we have already had under consideration, that the hymenium is never exposed. The perithecium consists usually of an external layer of cellular structure, which is either smooth or hairy, usually blackish, and an internal stratum of less compact cells, which give rise to the hymenium.

FIG. 35.-Perithecium of Sphæria and Section.

As in the Discomycetes, the hymenium consists of asci, paraphyses, and mucilage, but the whole forms a less compact and more gelatinous mass within the perithecium. The formation and growth of the asci and sporidia differ little from what we have described, and when mature the asci dehisce, and the sporidia alone are ejected from the ostiolum. We are not aware that operculate asci have yet been detected. It has been shown in some instances, and suspected in others, that certain moulds, formerly classed with Mucedines and Dematiei, especially in the genus Helminthosporium, bear the conidia of species of Sphæria, so that this may be regarded as one form of fruit.

Perithecia, very similar externally to those of Sphæria, but containing spores borne on slender pedicels and not enclosed in asci, have had their relations to certain species of Sphæria indi*Duby, "Mémoire sur la Tribu des Hysterinées," 1861. Tulasne,"Selecta Fungorum Carpologia," vol. iii.

cated, and these are no longer regarded so much as species of Hendersonia or Diplodia as the pycnidia of Sphæria. Other and more minute perithecia, containing minute, slender stylospores in great numbers, formerly classed with Aposphæria, Phoma, &c., but are now recognized as spermogonia containing the spermatia of Sphæria. How these influence each other, when and under what circumstances the spermatia are instrumental in impregnation of the sporidia, is still matter of mystery. It is clear, however, that in all these conidia, macrospores, microspores, and some spermatia, or by whatever names they may be called, there exists a power of germination. Tulasne has indicated in some instances five or six forms of fruit as belonging to one fungus, of which the highest and most perfect condition is a species of Sphæria.

FIG. 36.-Uncinula adunca.

PERISPORIACEI-Except in the perithecia rupturing irregularly,. and not dehiscing by a pore, some of the genera in this group differ little in structure from the Sphæriacei. On the other hand, the Erysiphei present important and very interesting features. They occur chiefly on the green parts of growing plants. At first there is a more or less profuse white mycelium.* This gives rise to chains of conidia (Oidium), and afterwards small sphæroid projections appear at certain points on the mycelium. These enlarge, take an orange colour, ultimately passing into brown, and then nearly black. Externally these perithecia are usually furnished with long, spreading, intertwined, or branching appendages, sometimes beautifully branched or hooked at their tips. In the interior of the receptacles, pear-shaped or ovate asci are-formed in clusters, attached together at the base, and containing two or more hyaline sporidia. Other forms of fruit have also been observed on the same mycelium. In an exotic genus, Meliola, the fulcra, or appendages, as well as the mycelium, are black, otherwise it

*Tulasne, "Selecta Fungorum Carpologia," vol. i. Léveillé, "Organisation, &c., sur l'Érysiphé,” in “Ann. des Sci. Nat." (1851), vol. xv. p. 109.

is very analogous to such a genus of Erysiphei as Microsphæria. In Chatomium, the perithecia bristle with rigid, dark-coloured hairs, and the sporidia are coloured. Our limits, however, will not permit of further elucidation of the complex and varied structure to be found amongst fungi.*

* Other works besides those already cited, which may be consulted with advantage on structure, are-

Tulasne, L. R. and C., various articles in "Annales des Sciences Naturelles," série iii. and iv.

P.

Hoffmann, "Icones Analytica 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.

66

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), 335.

Cornu, M., "Sur les Saprolegniées," in "Ann. des Sci. Nat." p. 5.

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

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

Bonorden, H. F., "Abhandlungen ans dem Gebiete der Mykologie." 1861. Coemans, E., "Spicilége Mycologique." 1862, etc.

64

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 SPORIDIFERA, or sporidia-bearing, because in like manner the term sporidia is limited to such germ-cells as * Rev. M. J. Berkeley, "Introduction to Cryptogamic Botany" (1857), Lonlon, pp. 235 to 372.

+ De Bary, in "Streinz Nomenclator Fungorum,” p. 722.