164 INFECTIONS CAUSED BY MOLDS 



give rise to a series of round arthrospores. In a preparation from a 

 scutulum as described above, these elements become mixed togetlier 

 and one finds a melange of rounded cells, short oval cells, and longer 

 and shorter fragments of mycelium. The fungus has a similar struc- 

 ture in the hair ; one finds long, articulated filaments of cells of vary- 

 ing size, the terminal portions ending in a series of rounded arthro- 

 spores. A very characteristic feature is the degeneration and disap- 

 pearance of the fungus in the hair, which leaves a series of air 



bubbles. 



Cultures are obtained by inoculating minute portions of scutula 

 or hairs on the surface of agar slants. As these cultures are likely 

 to be contaminated by bacteria the specimens should be placed for 

 several minutes in 70 per cent alcohol and a large number should 

 be planted to increase the chance of obtaining some colonies reason- 

 ably pure. The particles of material are transferred to the surface 

 of the agar with a needle, and three or four widely separated inocula- 

 tions are made on a slant. The optimum temperature is 30° C. The 

 various strains vary considerably in rapidity of growth and in colony 

 pattern and several varieties have been named on the basis of this 

 variability. 



The colonies on agar are at first yellowish and waxy in appearance. 

 As they grow older they become much wrinkled and develop a short 

 whitish aerial mycelium (some strains may fail to do this). In cul- 

 tures the organism is extremely pleomorphic. In slow-growing 

 strains, the mycelium may become articulated and numerous chains 

 of arthrospores appear as in the lesions. In more rapidly growing 

 strains there occurs an extensive development of mycelium which is, 

 however, very irregular; it forms in some places thick, irregular 

 masses having little resemblance to ordinary mycelium. These are 

 called the ameboid forms. Large yellowish thick-walled cells may 

 appear in the course of the mycelium. Finally, filaments at the 

 periphery of the colony end characteristically in a branched cluster 

 of swollen cells. The latter structure is referred to as the favic 

 chandelier. 



In cultures which form a short aerial mycelium a few conidia can 

 usually be demonstrated. These are typical of the dermatophyte 

 conidia except that they are more variable in size and shape than in 

 most species. A few are so large as to suggest the macroconidia seen 

 in other species of Trichophyton. 



T. Schoenleini is apparently of variable pathogenicity for lower 

 animals. Typical scutula have been produced by inoculation of the 



