DAO FUNGI. 
detected. cidium compositarum and AHeidium ranunculacearum, 
for instance, are found on various composite and ranunculaceous 
plants, and as yet no sufficient evidence has been adduced to 
prove that the different forms are other than varieties of one or 
the two species. On the other hand, it is not improbable that 
two species of Zt cidium are developed on the common berberry, 
as De Bary has indicated that two species of mildew, Puccinia 
graminis, and Puccinia straminis, are found on wheat. 
Hypuouycetes.—The moulds are much more universal in their 
habitats, especially the Mfucedines. The Isariacei have a pre- 
dilection for animal substances, though not exclusively. Some 
species occur on dcad insects, others on decaying fungi, and the 
rest on sticks, stems, and rotten wood. The Stilbacei have also 
similar habitats, except that the species of £llosporium seem to be 
confined to parasitism on lichens. The black moulds, Dematici, 
are widely diffused, appearing on herbaceous stems, twigs, bark, 
and wood in most cases, but also on old linen, paper, millboard, 
dung, rotting fruit, &e., whilst forms of Cladcsporium and Mucro- 
sporium are met with on almost every kind of vegetable substance 
in which the process of decay has commenced. 
Mucedines, in some instances, have not been known to appear 
on more than one kind of matrix, but in the far greater number 
of cases they flourish on different substances. Aspergillus 
glaucus and Penicillium erustaceum are examples of these uni- 
versal Aluccdines. It would be far more difficult to mention 
substances on which these moulds are never developed than to 
indicate where they have been found. With the species of 
Peronospora it is different, for these are truly parasitic on living 
plants, and, as far as already known, the species are confined to 
certain special plants, and cannot be made to vegetate on any 
other. The species which causes the potato murrain, ulthough 
liable to attack the tomato, and other species of Solanaceae, does 
not extend its ravages beyond that natural order, whilst Pero- 
nospora parasitica confines itself to cruciferous plants. One 
species is restricted to the Umbellifere, another, or perhaps two, 
to the Leguminosae, another to Rubiacee, two or three to Ranun- 
culacee, and two or three to Caryophyllacee. All the experi- 
