Botrytis infes´tans is the potato-Fungus. It forms white spots upon the under side of the leaves of the potato-plant, and by some authors is considered to be the cause of the potato-disease. The filaments are branched at the ends, and terminated by single oval spores, which are apiculate at the free end, and contain minute little spores or sporidia.
Oid´ium Tuck´eri is the well-known destructive grape-Fungus. It forms white cottony masses upon the vine and its grapes, the fruit-stalks being short and terminated by one or two end-to-end oblong spores. It appears to be the Coniomycetous form of another Fungus (Erysiphe).
Trichothécium róseum ([Pl. VII.] fig. 33) is found upon rotting sticks; very frequently upon willow-baskets kept in a damp place. It forms little rounded, slightly raised, pinkish spots, less than the size of a pin’s head. The branched and septate foot-stalks (figs. 34, 35) are terminated each by a little group of obovate spores, divided by a transverse partition (uniseptate). Sometimes this little Fungus is quite white, at others greenish; when perfectly ripe, the spores become oblong.
Penicil´lium glaúcum ([Pl. VII.] fig. 25) is the common Blue Mould found upon decaying substances, as cheese, &c., the interwoven mycelial filaments often forming large cakes or crusts upon the surface. The septate fruit-stalks (fig. 26) are fork-branched at the ends, the branchlets being terminated each by a row of very minute spherical smooth spores. On some decaying substances, as apples, gum, &c., the fruit-stalks are found aggregated into a thick stalk, the branchlets and spores forming a rounded head, so that the whole resembles a little blue mushroom (fig. 27). In this form the Fungus has been placed in a distinct genus, and called Corémium leúcopus. In other species the spores are pink and white.
This little Fungus is of special interest, on account of one form of it constituting the yeast-plant, or yeast as it is commonly called. This consists of rounded or oblong cells, which grow very rapidly in fermenting liquids by budding—the large quantity of sugar and gluten present favouring the vegetative or simple growing process, at the expense of the fructifying process. But this is only an instance of what we constantly find in flowering plants, the use of very rich soil rendering flowers double, which is really reducing their organs to the state of leaves. When the sugar has become exhausted, the cells of the yeast become longer and thinner, as if starved; they then form a more recognizable mycelium, which extends to the surface of the liquid, and produces finally the fruit-stalks and the Penicillium fruit. Aspergil´lus glaúcus ([Pl. VIII.] fig. 3) is an extremely common mould upon cheese, jams, &c. It resembles the last in appearance to the naked eye, except that it has rather a green tinge, the heads of fruit being much more compact and rounded. The fruit-stalks (fig. 4) are large, bulbous or inflated at the ends (fig. 5), and from the inflations arise the crowded rows of spores. The spores are rounded, and rough (scabrous) on the surface. On removing most of the spores from the head of fruit, each row of spores is found to arise from a very short stalk.
Plate VII. fig. 21 represents a beautiful species of Rhinot´richum, which is found upon decaying and sickly plants, and upon rotting sticks, forming a minute grey mould. The fruit-stalks (fig. 22) are large, sparingly branched, septate or jointed, appearing brownish under the microscope. Their ends are branched, mostly biternate (fig. 23), i. e. each branch dividing into three branchlets, and these again into three still finer ones. The ends of the branchlets are inflated, and coated with little points, upon each of which a smooth white spore (fig. 24) is placed.
Ascomycétes (ἁσκὀς, a bottle, μὑκης, fungus). The Fungi belonging to this Order are found upon the stems and leaves of plants, and upon decaying substances, as dung, &c. They are usually evident to the naked eye, some even equalling the Hymenomycetous Fungi in size; and many of them are brilliantly coloured. They are in general distinguishable with facility from the Fungi of other Orders, by the arrangement of the spores in colourless sacs or asci ([Pl. VIII.] fig. 9), resembling those noticed in the case of the Lichens. These asci are usually enclosed in a capsule or perithécium. The mycelium is usually buried in the matrix, so as not to be conspicuous.
Helvellácei.—To this family belongs the large genus Pezíza, some of the species of which are beautifully coloured, yet scarcely microscopic. Among these may be mentioned Pezíza omphalódes ([Pl. VIII.] fig. 6), which forms little red masses upon damp ceilings. It does not possess the ordinary form of a Peziza, which is that of a cup fixed at the end of a stalk, like a mushroom with the cup turned inside out, the asci lining its interior.
Peziza coccin´ea is not uncommon in woods. It is whitish outside, the interior of the cup being of a brilliant scarlet colour. It is from half an inch to an inch in height.
Peziza stercor´ea ([Pl. VIII.] fig. 7) is often found upon dung. The surface of the cup of this Fungus is granular and covered with bristles (figs. 8 & 11). The cup is concave (fig. 10), and lined with the asci (fig. 9), among which are simple paraphyses.