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 development of other associated Fungi. The merit of first breaking ground in this direction belongs to the brothers Tulasne, who published before 1850 the first more exact researches into the Smuts and Rusts; these were followed by a long series of excellent works on different forms of Fungi, especially the subterranean, whose mode of life and anatomy were described and illustrated by splendid figures; but their account of the development of Ergot of rye (1853), their further investigations into the formation of the spores and the germination of Cystopus, Puccinia, Tilletia, and Ustilago, and their discovery of the sexual organs in Peronospora before 1861, were of greater theoretical importance. The ‘Selecta Fungorum Carpologia,’ which appeared in three volumes from 1861 to 1865 with fine figures, some of which represented the process of development, contributed greatly to the reformation of mycology. Meanwhile, Cessati had published investigations into the Muscardine-fungus of the silkworm-caterpillar, and Cohn into a remarkable Mould, the Pilobolus.