sexuality in a Mould, namely, the conjugation of the branches of Syzygites. In the same year Nees von Esenbeck sowed Mucor stolonifer on bread, and obtained ripe sporangia in three days (Flora, 1820, p. 528); Dutrochet proved in 1834 (Mém. ii. p. 173) that the larger Fungi are only the sporophores of a filiform branching plant, which spreads usually under ground or in the interstices of organic substances, and had been till that time regarded as a peculiar form of Fungus under the name of Byssus. Soon after, Trog (Flora, 1837, p. 609) carried these observations further; he distinguished the mycelium from the sporophore, and pointed out that the former is often perennial and is the first product of the germinating spores. He made an attempt to examine the morphology of the larger sporophores, and showed that it was possible to collect the spores of mushrooms on paper, and that those of Peziza and Helvella are forcibly ejected in little clouds of dust; he also produced new proofs of Gleditsch's statement, that the spores of Fungi are disseminated everywhere by the air. Schmitz published in 'Linnaea,' between the years 1842 and 1845 excellent observations on the growth and mode of life of several of the larger Fungi. It was not unnecessary at that time to make it clearly understood that the spores of Fungi reproduce their species exactly.
But the lower, the small and simple Fungi, those especially which are parasitic on plants and animals, were the most attractive objects in the whole field of mycology. Here were difficulties in abundance, here were the darkest enigmas with which botany has ever had to deal, here was new ground to be slowly won by extreme scientific circumspection and foresight. In these forms, as in the Algae, the first thing to be done was to make out the complete history of development in a few species; but it was much more difficult in the Fungi than in the Algae to discover what properly belonged to one cycle of development, and to separate it from casual phases of develop-
