376 DIVISION III.—MODE OF LIFE OF THE FUNGI. 
of spores. It would of course alter the case if there were distinct parasitic species 
of Saprolegnia different from the common ones, but we know of no such species 
at present. 
The remarks here made apply on the whole to the epidemic among salmon 
investigated by Huxley, but some points require further explanation. The Fungi in 
this case appear on the outer surface of the skin in the form of ordinary Saprolegnieae ; 
they could be transferred by tapping to dead flies and be made to develope further on 
them, but their gonidia are described as being always without motion. This at once 
raises the question whether they really belong to Saprolegnia, and at any rate it is 
quite uncertain whether we are dealing with a case of facultative parasitism in 
species which are usually saprophytic or with one or several peculiar and specifically 
parasitic forms. 
Section CVI. The following are the best-known species of Fungi of 
diseases of the skin. Achorion Schoenleinii, Remak, the Fungus of favus, 
Trichophyton tonsurans, Malmsten, the Fungus of ringworm or tinea (herpes) 
tonsurans which is identical according to Köbner with that of sycosis or mentagra 
parasitica (Microsporon Audouini and M. Mentagrophytes, Rob.; Microsporon 
furfur, Rob., the Fungus of pityriasis versicolor'). These Fungi are parasitic on the skin 
of different mammals and birds. They grow luxuriantly in and beneath the epidermis, 
in the hair-follicles and hairs. Their appearance on the human skin is characterised’ 
by the forms of disease enumerated above. Trichophyton tonsurans has also been 
observed on horned cattle, horses, dogs, and rabbits, Achorion on the domestic mouse, 
the rabbit and the head of domestic fowls; Microsporon furfur was seen by Köbner 
on rabbits after inoculation. They may all be conveyed from one individual to another, 
from men to other animals and vzce versa by sowing their spores, and as these develope, 
the characteristic disease in each case makes its appearance. Transference by 
inoculation can be successfully performed on sound individuals, but certain forms of 
predisposition in the patient, which we cannot discuss here, appear to favour or to 
hinder the development of the Fungus. 
Of these Fungi as they appear in and on the portions of the skin attacked by 
them we know only the septate mycelial hyphae, the branches of which divide trans- 
versely into rows or chains of spores capable of germination and resembling those 
of Oidium lactis or the chain-gemmae of Mucor (see pages 67 and 155). When 

1 Remak, Diagnost. u. Pathogen. Unters. Berlin (1845), p. 193. 
Köbner, Ueber Sycosis, &c. in Virchow’s Arch., XXII (1861), p. 372;—Id., Klinische u. experi- 
mentelle Mittheil. aus d. Dermatologie u. Syphilidologie, Erlangen, 1864. 
Strube, Exanthemata phyto-parasitica eodemne fungo efficiantur (Diss. inaugur. Berolini, 1863). 
J. Lowe, On the identity of Achorion Schönleinii and other veg. parasites with Aspergillus 
glaucus (Ann. mag. nat. history, ser. z, XX (1857), p. 152). 
W. Tilbury Fox, Skin diseases of parasitic origin, London, 1863. 
Kleinhans, Die parasitären Hautaffectionen, Erlangen, 1864. 
P. J. Pick, Unters. ii. d. pflanzlichen Hautparasiten (Verhandl. d. Zoolog-Bot. Ges. in Wien, 
XV, 1865). 
J. Peyritsch, Beitr. z. Kenntn. d. Favus (Medicin. Jahrb. Bd. XVII, Wien (1869), Heft II, p. 61). 
P. Grawitz in Virchow’s Archiv, 70, p. 546. = 
Ed. Lang, Vers. einer Beurth. d. Schuppenflechte (Vierteljahrschrift f. Dermatologie u. Syphilis, 
1878, p. 333) ;—Id., Vorläuf Mittheil. ii. psoriasis (Ber. d. naturw. Med. Vereins z. Innsbruck, 
VIII, 1878). 
