. Fungi; their nature and uses. Fungi. STRUCTURE. 43 shall obtain some notion of the prevalent structure. In the former the threads are more or less carbonized, in the latter nearly colourless. One of the largest genera in Dematiei is Helminthosporium. It appears on decaying herbaceous plants, and on old wood, forming effused black velvety patches. The mycelium, of coloured jointed threads, overlays and penetrates the matrix ; from this arise erect, rigid, and usually jointed threads, of a dark brown, nearly black colour at the base, but paler towards the apex. In most cases these threads have
. Fungi; their nature and uses. Fungi. STRUCTURE. 43 shall obtain some notion of the prevalent structure. In the former the threads are more or less carbonized, in the latter nearly colourless. One of the largest genera in Dematiei is Helminthosporium. It appears on decaying herbaceous plants, and on old wood, forming effused black velvety patches. The mycelium, of coloured jointed threads, overlays and penetrates the matrix ; from this arise erect, rigid, and usually jointed threads, of a dark brown, nearly black colour at the base, but paler towards the apex. In most cases these threads have an externally cortical layer, which imparts rigidity; -usually from the apex, but sometimes laterally, the spores are produced. Although some- times colourless, these are most com- monly of some shade of brown, more or less elongated, and divided trans- versely by few or many septa. In Helminthosporium Smitliii, the spores much exceed the dimensions of the threads ; * in other species they are smaller. In Dendryphium, the threads and spores are very similar, except s& that the threads are branched at their apex, and the spores are often pro- u duced one at the end of another in a short In Septosporium again, the threads and spores are similar, but the spores are pedicellate, and at- FlG_ 2s.„_He,milMosporimn molle. tached at or near the base; whilst in Acrothecium, with similar threads and spores, the latter are clustered together at the apex of the threads. In Triposporium, the threads are similar, but the spores are tri-radiate ; and in Helicoma, the spores are twisted spirally. Thus, we might pass * Cooke, " On Microscopic Moulds,'' in " Quekett Journal," vol. ii. plate 7. f See "Dendryphium Fumosum," in " Quekett Journal," vol. ii. plate 8; or, " Corda Prachtflora," plate Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and
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