TRICHOPIIYTON TONSURANS 233 



and grow together into a colourless tuft of mycelium. 

 If they rise to the surface, the part exposed to the 

 action of the air becomes very speedily covered with 

 a snow-white powder, which lends the surface, seen from 

 above, the appearance of a, membrane, and which gradu- 

 ally becomes yellow. Already in the earliest stages of 

 development there occur in the mycelial tubes dilatations 

 resembling ampullae and filled with a granular mass, and 

 these are taken to be the spores of the mycelium. The 

 tubes enlarge and become segmented, which causes a dis- 

 tinct resemblance to a string of pearls ; the mycelium now 

 gradually becomes finer, the divisions are small, and show 

 smooth walls with bulgings. Yerujski has shown experi- 



FIG. 87. MYCELIUM FILAMENTS OF TIUCHOPHYTOX ToxsuitAxs, FROM A PURE 

 CULTURE ov INKUSIOX OP MALT. (After Leslie Roberts.) 



mentally that glucose, and not, as Grawitz supposed, a 

 nitrogenous body, is the medium suitable for the tricho- 

 phyton. The development, therefore, of the tonsurans 

 fungus in the epithelium of the skin covering the body does 

 not progress by means of spores, but merely by the swelling, 

 constriction, and final separation of fibres (fig. 87) . 



This fungus is also, according to H. von Hebra, the 

 exciting cause of impetigo contagiosa (an exanthem charac- 

 terised by the formation of pustules), as well as of eczema 

 marginatum, [and it is now agreed that tinea sycosis, tinea 

 circinata (common ringworm), and onychomycosis (an 

 affection of the nails) are due to it. (See also note at end 

 of chapter.)] 



Gelatine is quickly and actively liquefied, according to 



