Etiology. 901 



Cultivation. Cultures of the tricophyton fungus are hard to ob- 

 tain because it is difficult to isolate it from the germs of other fungi 

 occurring on the skin. For this reason Sabouraud used wort as a 

 medium for the culture of the tricophyton fungus, or a medium com- 

 posed of four parts of maltose, 2 parts of peptone, 1.5 parts of agar 

 and 100 parts of the distilled water on which only the tricophyton grows 

 luxurianth', while Krai effected the isolation by grinding the hair 

 with pulverized silicic acid and subsequent plate culture. Sabouraud 

 only places the broken up roots of the pulled-out hairs upon the culture 

 medium in order to prevent as much as possible infection with the 

 other microorganisms infesting the hair shafts. Pure cultures may 

 also be olitained by treating the pathological products with potassium 

 hydrate and other chemicals, whereby the tricophyton remains uninjured 

 while other fungi are destroyed (Kitt). 



The tricophyton fungus develops on culture media rich in carbo- 

 hydrates and poor in protein, in the presence of oxygen. For its 

 growth a temperature of 33° C. is most suitable, while above the body 

 temperature the growth is very scanty or ceases altogether; at a tem- 

 perature of 20 to 24° C. it does fairly well, but in a lower temperature 

 it makes very slow progress (Bodin). Gelatine is liquefied and 

 a substance with ammoniacal smell is formed, and there develops 

 gradually a leatherish, mealy looking, firmly coherent deposit, the 

 under side of which is usually sulphur yellow, while the surface appears 

 white ; after long standing yellowish or reddish tints may be seen. The 

 growth of the fungus becomes especially firm and dry on agar (Kitt). 

 On potatoes a wrinkled, fuzzy skin-like covering develops, which is white 

 or yellow, reddish or even brownish in color. 



Cultures of the tricophyton fungus like that of the filament fungi 

 of the skin in general are characterized by a rather marked pleomorphism 

 and by great variability, according to their age and origin, as well as 

 according to the composition or age of the culture medium (Krai). 

 Considerable differences present themselves not only as regards pigment 

 formation but also the size of the conidia spores. On the surface of the 

 animal body the tricophyton fungus increases exclusively by the forma- 

 tion of socalled mycelium spores, which arise by division of the proto- 

 plasm of the hyphfe into four-cornered cells by transverse septa, these 

 cells become rounded off, are detached and after germination again de- 

 velop into hyphffi. On artificial media spores (socalled chlamydospores) 

 may also be' formed by separation of parts of the protoplasm within the 

 hyphse. But spores also arise by lateral sprouting, and in the filament 

 fungus more or less closely placed pear-shaped inverted projections 

 arise, which soon assume a round form and then are detached (conidia) ; 

 the conidia-bearing hyphffi appear either in clusters (according to French 

 authors the tricophyton in its limited sense), or they may show a crest- 

 shaped form on account of the closely placed projections (according to 

 French authors the microsporum). Now and then much larger elongated 

 oval, often multicellular spindle spores arise by the development of pro- 

 jections (also called lateral chlamydospores). One also meets Avith 

 spirally rolled hypha? in the cultures. The mode of fructification is 

 much influenced "by the composition of the culture medium. 



On account of cultural peculiarities and clinical differences many 

 authors (Sabouraud, Bodin, Megnin, Almy & Bodin and others) dis- 

 tinguish several kinds of tricophyton fungi which are said to cause 

 different forms of illness. Thus Sabouraud divided the filament fungi 

 concerned in the production of herpes into two great groups. The 



