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THE ACTINOMYCETES, Vol. I 



Figure 46. Colony variants of S. yrisciis (Reproduced from: Didaney, E. L. ct al. Mycologia 41: 390, 

 1949). 



aerobically and nonpathogenic. 2. 0-type 

 — gram-positive, diphtheria-like rods, con- 

 sidered as anaerf)}nc transition forms, capa- 

 ble of developing in the human organ- 

 ism. 3. R-type — large colonies, made up of 



aerobic, gram-positi\'e rods. This cyclic de- 

 \'elopment was said to be accompanied by 

 changes in the cultural, morphological, and 

 biochemical properties of the organism. 

 Ilenrici, however, emphasized that the 



