BLASTOMYCETES 387 



have not as yet been sufficiently studied to justify their separation 

 as distinct species, but will be treated rather as one polymorphic 

 form. Careful morphological and cultural studies are still needed. 

 In the tissues the organisms appear almost invariably as 

 budding forms. The cells are spherical or ovoid, from 10 to 17 (J> 

 in diameter. They are distinctly double contoured. Several 

 investigators have observed what they believe to be sporulating 

 forms. The cells are frequently granular or vacuolate, resembling 

 typical yeast cells in this respect. Upon culture-media numerous 

 hyphal threads and budding cells are produced. 



'1'f-^' 



Fig. 169. Blastomyces dermatitidis. Budding forms and mycelial growth 

 from glucose agar (Irons and Graham, in "Journal of Infectious Diseases"). 



The organisms do not stain very readily with the aqueous 

 anilin dyes. 



Isolation and Culture. Isolation of the organism is usually 

 attended with considerable difficulty. Blood-serum slants are 

 usually employed and inoculated with material from the lesion. 

 Repeated trials are sometimes necessary before a growth is secured. 

 After once accustomed to growth on artificial media, no difficulty 

 is found in getting the organism to develop upon most of the 

 common culture-media. 



Small white colonies showing a mold-like surface, due to the 

 formation of numerous aerial hyphae, develop upon the surface 



