_Æcid´ium grossuláriæ_ (Pl. VII. fig. 8) is found very commonly on the leaves of the gooseberry-bush. It forms to the naked eye oval or rounded spots (_sori_), of a red colour; and on close examination, the spots appear dotted with yellow points. Each point is the orifice of an open capsule (_peridium_), which has burst through the epidermis of the leaf (Pl. VII. fig. 9 _p_). The capsules are split or lacerated at the margins, and form little cups containing the spores. The spores are very minute, yellow, and are arranged in closely packed moniliform rows. The red colour depends upon the altered chlorophyll of the leaf. On the leaves containing the spore-capsules or peridia will be found smaller, brownish-yellow capsules (_spermogonia_) partly imbedded in their substance (Pl. VII. fig. 9 _s_). These contain minute filaments (_sterigmata_), terminated by short rows of rounded cells (_spermatia_), which are supposed to exert an antheridial function. The species of _Æcidium_ are very numerous, and many of them are extremely common--as those upon the nettle, the barberry, the dandelion, the wood-anemone, the violet, and buttercups. The groups of capsules form exquisite opake objects under a low power of the microscope. _Phragmid´ium bulbósum_ (Pl. VII. fig. 14) is another very beautiful coniomycetous Fungus. It forms little reddish, afterwards sooty dots upon the under surface of the leaves of various species of Bramble (_Rúbus_). The oblong spores (fig. 15) are from 2-to 4-septate, and stalked, the stalks being swollen or bulbous at the base. The spores, which appear brown when magnified, are covered with little knobs (tuberculate) on the surface; and the uppermost little spore or sporidium is terminated by a minute point (apiculate). Among the spores are numerous barren filaments or paraphyses. _Puccin´ia gram´inis_ (Pl. VII. fig. 16) is to be found everywhere upon damp rotting straw, and upon grasses. It forms sooty irregular streaks, consisting of densely crowded, one-partitioned (uniseptate) spores (fig. 17), which appear brown under the microscope. This Fungus is sometimes called “mildew.” There are numerous other species of _Puccinia_ which occur upon common plants. _Urédo seg´etum_ is the “smut” of wheat, barley, and oats--a fungus too well known to the farmer. It forms sooty masses, bursting through the epidermis of the stalk and ears of the corn, and soiling the fingers when handled. The spores (Pl. VII. fig. 5) are exceedingly minute, and the stalks are so slender and loosely connected with them that they are not readily detected. Under the microscope the spores appear brown and faintly dotted, this appearance arising from a reticulated structure of the surface, similar to that of the poppy-seed on a very small scale.