TAXONOMY 221 



2. Flagella and endospores present Bacillus. 

 Family III. Spirillaceae. Cells curved or spirally bent, generally 

 motile through polar flagella. 



1. Cells stiff, not flexile. 



(a) Cells without flagella Spirosoma. 



(b) Cells with one, very rarely with two polar flagella Micro- 

 spira. 



(c) Cells with a bundle of polar flagella Spirillum. 



2. Cells flexile, spiral very close Spirochaeta. 



Family IV. Mycobacteriaceae. Cells short or long cylindrical 

 or clavate-cuneate in form, without a sheath surrounding the 

 chains of individuals, without endospores, with true dichotomous 

 branching. 



FIG. 108. Types of spirilla. (After Williams.) 



A. In cultures possessing the characters of true bacteria. Growth 

 on solid media smooth, flat, spreading. Rod with swollen ends, 

 or cuneate or clavate forms Corynebacterium. 



B. Cultures on solid media raised, folded or warty. Generally 

 short slender rods, rarely short branched. Take the tubercle stain 

 Mycobacterium. 



Family V. Chalamydobacteriacese. Thread-like, composed of 

 individual cells, surrounded by a sheath. Simple or with true 

 branching. Ordinary vegetative growth by division in only one 

 direction of space, i.e., at right angles to the longer axis. 



A. Cell contents without sulphur granules, 

 i. Filaments unbranched. 



(a) Cell-division only in one direction of space. 



(b) Cell-division in gonidial formation in three directions 

 of space Streptothrix. 



*Marine forms with cells ^surrounded by a very delicate 

 hardly discernible sheath Phragmidiothrix. 



