46 CLASSIFICATION 



Key to the Families of the Order Actinomycetales. 



1. Filamentous forms, frequently branched, 



saprophytes and some parasites . . I. Aclinomycelacece 



2. Rod shaped, exceptionally filamentous 



or branched II. Mycohacteriacecc 



Key to the Genera of Mycobacteriace^. 



1. Gram-positive 



a Acid-fast 1, Mycobacterium (tubercle bacilli) 



aa Not acid-fast . . .2. Corynebacterium {diphtheria) 



2. Gram-negative 



a Cells frequently fusiform 3. Fusiformis 

 aa Cells not fusiform . . 4. Pfeifferella (glanders) 



