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 Kobner with that of sycosis or mentagra 

 parasitica (Microsporon Audouini and M. Mentagrophytes, Rob. ; Microsporon 

 furfur, Rob., the Fungus of pityriasis versicolor l ). 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 Kobner 

 on rabbits after inoculation. They may all be conveyed from one individual to another, 

 from men to other animals and vice 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. 



Kobner, 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 Schonleinii and other veg. parasites with Aspergillus 



glaucus (Ann. mag. nat. history, ser. 2, XX (1857), P- I 5 2 )- 

 W. Tilbury Fox, Skin diseases of parasitic origin, London, 1863. 

 Kleinhans, Die parasitaren 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., Vorlauf Mittheil. ii. psoriasis (Bar. d. naturw. Med. Vereins z. Innsbruck, 



VIII, 1878). 



