The most important are: -

(a.) The myeoderma in tinea favosa (Schonlein, Gruby). Shut up in splitting capsules, it constitutes the skin-imbedded favus. These fungi, like the torula cerevisiae, present in their most simple form, roundish or oval cells, and these put forth buds, which shoot out into simple or branched threads. The favus-fungus belongs to the genus Oidium (Linck), and according to Muller greatly resembles the oidium aureum of wood. Or, according to Corda, it may, together with all thread-funguses, which fructify by simple separation of their links, and in which every link may become a spore, be taken, along with yeast funguses, into the great genus Torula.

1 [It is now, however, pretty generally admitted to be an alga. - Ed].

There is as yet no certainty as to the part played by these thread-funguses. Attempts at inoculation have hitherto failed, with the exception of one experiment made by Remak.

(b.) Fungi in the root-sheath of the hair in sycosis [mentagra, Gruby]. They collect around the hair itself within the root-sheath, and are marked by redundant spore-formation. The spores are spherical and the thallus-threads frequently contain in their interior little granules.

(c.) Fungi in the interior of the hair-roots [Gruby]. In alopecia circumscripta, areata [porrigo decalvans], the falling out of the hair is caused by a thread-fungus, called by Gruby, on account of the minuteness of its spores, microsporum.

(d.) In plica Polonica, Gunsburg has detected, in the hair-bulbs, a fungus which differs from that of favus.

(e.) In Pityriasis versicolor, Eichstedt has discovered a thread-fungus.

Fuchs, Klenke, Helmbrecht, have observed a fungus formation in lepra alphoides, and inoculated it with success.

Langenbeck met with a fungus in crusta serpiginosa.

Finally, the mould formations upon sloughing ulcers, and in senile gangrene, come under this head. They are both frequent and copious.