Cultivation 749 



Specific Organism. The organism presents a variety of appear- 

 ances which may be thus brought together: First, there are round 

 and elliptical disk-like bodies that some regard as spores, others as 

 the primitive or yeast form. These measure 10 to 30 p in greatest 

 diameter, are distinctly doubly contoured, highly refracting, and, 

 though sometimes clear and transparent, are frequently granular and 

 vacuolated. From them buds may grow, as in the yeasts, or hypha 

 may form, as in oidium. In artificial cultivations the hypha may 

 form a tangled mycelium. 



Staining. The organisms are usually better found without 

 staining. They do not stain with aqueous anilin dyes, but are pene- 

 trated by warm thionin, alkaline methylene-blue, and polychrome 

 methylene-blue. In sections of tissue stained with hematoxylon 



Fig. 312. Giant cell from a cutaneous lesion in blastomycosis, showing a group 

 of blastomyces (Montgomery). 



and eosin they show as uncolored circles; with thionin and alkaline 

 methylene-blue they may take a blue color. 



Cultivation. -The organism grows readily upon artificial media 

 when once started, but the primitive culture is difficult to secure, 

 because the cocci and other associated organisms are more numerous 

 than the blastomyces and outgrow it. It seems most satisfactory 

 to first infect a guinea-pig with the organism from the skin, and then 

 start the cultivation from its lesions than to attempt it directly from 

 the pus from human dermal lesions. When the human lesions are 

 internal, pure cultures are easily started. 



Gilchrist and Stokes* were able to start cultures directly from the 

 dermal lesions. Hiss and Zinsser recommended that this be done 

 * "Journal of Experimental Medicine," 1898, m, 53. 



