CULTIVATION AND COLONIES 



663 



employment of nutrient gelatine, nutrient agar-agar, aiul other 

 similar media on glass plates, and in test-tubes (fig. 501), so as 1>\ 



FIG. 501. Pure-cultivations of Streptococcus pyogenes : a, on the surface of 

 nutrient gelatine ; &, in the depth of nutrient gelatine ; e, 011 the surface of 

 nutrient agar. (Crookshank.) 



FIG. 502. Colonies of Bacillus anthracis, x 80 : a, after 24 hours ; 

 6, after 48 hours. (Fliigge.) 



inoculation to obtain cultures of specific and isolated forms with 

 their characteristic appearances, is one of the essential methods 



