822 



Blastomycosis 



from the dermal lesions. Hiss and Zinsser recommended 

 that this be done by greatly diluting the culture material, so 

 as to separate the contained organisms widely. 



Many culture-media prove appropriate, glycerin agar-agar 

 and agar-agar containing i per cent, of dextrose being ex- 

 cellent. When once isolated the organism is easily kept 

 growing by transplanting every month or two. 



Fig. 278. Cultures of Blastomyces dermatitidis upon solid culture- 

 media (Montgomery). 



The colonies appear in a few days as small round hemi- 

 spheric dots with numerous prickles about the surfaces. 

 Later they have a moldy appearance from the develop- 

 ment of aerial hypha. They are almost purely aerobic, 

 those on the surface growing well, those deeply seated in the 

 medium scarcely at all. 



Agar-agar Slants. These at first show a creamy white 

 layer that becomes quite thick, and is moldy and fluffy on the 

 surface. After a few weeks the agar-agar begins to turn 

 yellow and later may become brown, though the growth itself 



