552 TRICHOMYCETES, ACTINOMYCETES, HYPHOMYCETES 



anilin dyes and they are Gram-negative. They are best observed 

 unstained in hanging drop preparations previously treated with 

 NaOH, which brings out their outline sharply, also the refractile 

 layers of the cell membrane. Of particular importance is the recog- 

 nition of budding, which at once distinguishes the organisms. The 

 cytoplasm is granular while the cell as a whole possesses no flagella 

 and is consequently non-motile; the granules frequently exhibit 

 Brownian movement. 



Isolation and Culture. The Blastomycetes grow with moderate 

 luxuriance upon Loffler's blood serum and glucose agar. Initial pure 



FIG. 90. Blastomyces, maltose broth culture. 



cultures are somewhat difficult to obtain, however, chiefly because 

 adventitious organisms are almost always present, which overgrow 

 the more slowly developing Blastomycetes. It is necessary to dilute 

 material containing the organisms with sterile salt solution or broth 

 and to crush the tissue into minute fragments. Once pure colonies 

 are obtained, their perpetuation by subculturing is readily accom- 

 plished. Slightly acid maltose agar, according to Ricketts, 1 is an 

 excellent medium both for isolation and subsequent cultivation. The 

 colonies upon solid media are at first small, white, elevated plaques 

 which later become gray or brownish. After a few days the growth 

 becomes wrinkled and the mycelial threads and aerial hyphse develop, 

 which gives the culture a moldy appearance. The hyphse fill the 

 tube around the colony. In fluid media the growth at first is a floc- 

 culent mass which collects at the bottom of the tube; a membrane 

 or pellicle usually develops on the surface of the medium, falls to the 



1 Jour. Med. Research, 1901, vi, 377. 



