Page:Encyclopædia Britannica, Ninth Edition, v. 9.djvu/868

 832 FUNGUS of life. They are very injurious, especially to the Graminece. The power of producing many sporidia in succession, pos sessed by the promycelium, tends to the plentiful distribution of the disease. These sporidia usually attack the axis of germinating plants, in which a mycelium is then developed and carried up with the growth of the plant, ultimately pro ducing spores in the fruit and causing its destruction. Order III. BASIDIOMYCETES. The only form of repro duction known in this order is by asexual spores borne at the apex of erect basidia. These spores reproduce the plant directly without the intervention of another generation. The receptacle of the hymenium consists of interwoven hyphie, and is gelatinous, fleshy, or woody in consistency ; it sometimes attains great size. The mycelium is compara tively small and floccose. Suborder I. Tremellini. The hymenium of this sub order bears two different kinds of basidia in different genera. In the genus Tremella the basidia are at first subglobose or (p.iite spherical, and divided from top to bottom into four equal parts. These segments either remain united, or diverge, while they grow out to the margin of the fungus in the form of long liyphse bearing kidney-shaped spores. In Dacrymyces and Guejnnia the basidia are at first clavi- furm then divergent into two arms, bearing one reniform spore each. Spermatia are often met with abundantly in many of the Tremellini. They are produced in regular spermatophorous apparatus, and are very minute and spherical or ovoid. Like the spermatia of the Uredinece, their function is unknown. The consistence of these plants is gelatinous, with, in some cases, a denser nucleus. They are usually to be found growing on stumps of trees and on the ground. Their chape, when they have one, is usually more or less cup-like. Suborder II. Ilymenomycetes. The Ilymenomycetes is the most widely-known group of fungi. It includes the com- C v Fir,. 3 . Ayariftis miisrarius. A, the young plant ; B. Hie mature plant; C lon gitudinal section of mature plant. j&amp;gt;. the^iY/ Uj; g, the gills; a, the annul in return partiale, r, remains of rotra or velum umrersale; s. the mon mushroom, to which all the species bear more or less resemblance. The familiar form is that of a pileus raised upon a stalk and bearing on its under surface the hymenium extended over gills or lamella (Agarlcini), pores (Poiyporei), or teeth (Hydnacei}. From the hymenium rise the basidia] at the apex of which are usually four sterigmata bearing the spores. These spores are asexually produced, and on germinating, by emitting a hypha, give rise to a new mycelium on which the receptacle is again borne. The stion of the existence of a form of sexual reproduction &amp;gt;t With no certain result. Among the basidia are to be een other cells of similar shape, but of greater dimensions. called cystidia; 1 it has been contended that these are male organs. The mycelium is nearly always underground. The Ayaricini possess an inferior hymenium spread over lamellai or gills radiating from the stalk. These are some times simple and sometimes branched, and attached to or distinct from the stalk. The spores vary much in colour, one colour being constant to a genus or to a subgenus. On the stems of some genera an annulus or ring may be found, as a remnant of a veil (velum partiale) which united that part of the stem with the outer edge of the cap or pileus, but was ruptured on the expansion of the latter. In certain subgenera of Ayaricus (f.y., Volaria, Amanita) the whole FIG 4 Agaricus mucidtil. Portion of hymenium (x 350). ., sporidia ; st, stcrig- mata. &amp;lt;?, steiile cells; r, cystidium, with operculiim o. plant is, when young, enclosed in a volva (velum -universal?), the remains of which may be seen in mature plants adhering to the base of the stem. In some genera, as in Amanita, both forms of veil are found together. When the stem is lateral, as in Fleuroius, it is usually very much suppressed. The species of Agarcini are usually terrestrial, many of them are edible, and a few are deadly poisons. The Polyporei are distinguished by the hymenium (some times inferior, sometimes superior) extending over the sur faces of cavities or pores. In the genus Boletus the habit of an Agaric is assumed the stem usually central, the tex ture almost always soft. In Polyporus the stem is usually 1 iteral and the texture woody. The hymenophore is not easily separable. In some cases the habit of Polyporus is crust-like, the pores opening upwards, when it is called resupinale. Polypori grow r usually on stumps of trees. The Hydnacei possess an inferior or an amphigenous hymenium spread over teeth or spines. Some of the species have the form of a stalked pileus with the teeth inferior, while others resemble the resupinate Polypori. They are fleshy or corky in texture. In the Auricularini the hymenium is confluent with the hymenophore. In form they resemble the Polyporei. The Clavarinei are distinguished by an amphigenous hymenium, scarcely distinct from the hymenophore, and reaching to the apex of the plant, which is club-shaped, or in the form of upright spines. The species are gelatinous in consistence, but become horny when dry. The surface is usually smooth at first but afterwards assumes an in dented or wrinkled appearance. 1 Mr W. G. Smith, who lias examined a large number of cystidia, especially among the Ayaricini, states that they nil normally open by an orifice capped by a minute operculum at. the top. In Co}irinus ihc cystidia are unusually large, with at first a rounded top, which at length is capped by a nipple-like protuberance. After the careful examina tion of a large number of specimens Mr Smith has convinced himself that the apex of each cystidium is furnished with a minute operculum, which is burst off in the discharge of the liquid or granular contents of the cystidium. In Lactarius the opercnlum is tall and cap-like. The liquid secreted by the cystidia of the Ayaricini is sometimes granular before liberation, but in other cases not until after. When this granular matter is ripe, the grains revolve and move freely about, and if the opercnlum do not readily open this motion is increased until an opening is forced. Mr Smith looks on these granular bodies as analogues of antherozoids.
 * he Ilymenomycetes has been fought over many times, as