The order Dematiei are the black moulds found on damp paper, old damp linen, dead wood and plants. Their spawn is seldom much developed, the fertile threads are erect, rigid, dark brown approaching to black, sometimes of an olive green. The spores on their tops are either simple, in whorls, or collected into heads, which are large, septate, and even spiral. The Mucedines are beautiful microscopic objects both as to form and colour; they are very numerous both in genera and species and are well known as red, blue, or green moulds. These fungi spring from many points of a generally abundant mycelium, in erect coloured threads, bearing on their tips simple naked spores, spores collected into little tufts, or spores strung together like beads forming threads either branched or simple. In this order of fungi there are, moreover, instances of dualism, the second order of fruit being that of the family of the Ascomycetes. The Botrytis, or Peronospora infestans, which causes the murrain in potatoes, shows how destructive the Mucedines can be. Like other entophytes, its spores enter the stomates in the leaves of the potato, and fill the cavities of the leaves with spawn, the ramifications of which are said to be very beautiful. This creeping spawn then insinuates itself into the stem and tuber, and from thence it finds its way to the exterior of the plant, or to some internal cavity, where it fructifies, bearing large globose sessile bodies yielding fruit of the second order, and spores on the tips of its fertile branches. The spawn of the Botrytis spreads rapidly in a circle, and soon destroys the texture of the leaves and stem, but although it attacks the tuber or potato generally so called, it does not penetrate deeply. The destruction of the potato is aided and completed by the Fusisporium Solani, a microscopic fungus, which takes various forms according to its age and changing conditions, the last of which seems to be partly gelatinous; it sometimes hardens the tissues of the potato, but sometimes causes rapid and loathsome decay. The thread-like fibres of the spawn of the Peronospora permeate even the branches and wood of trees. Wasps are frequently seen to frequent hollow trees, probably in search of the mycelia of some of these parasitic fungi, which is identical in structure with the material of which their nests are built. Signore Panceri, professor of comparative anatomy in the university of Naples, has discovered seven species of Mucedines in the albumen of hens’ eggs.