CLASSIFICATION OF BACTERIA 21 



positive, not acid -fast. Characteristic snapping of cells in 

 division. (Diphtheria bacillus.) 



Genus 3. FUSIFORMIS. Cells elongate and fusiform, sometimes 

 filamentous, not branching. Non-motile, no spores. Para- 

 sitic. 



Genus 4. PFEIFFERELLA. Non-motile slender rods with ten- 

 dency to form threads with branching. Gram -negative. 

 Carbohydrates not fermented. Honey-like growth on potato. 

 (Glanders bacillus.) 



E. OEDEE EUBACTEEIALES. 



Includes the forms usually termed true bacteria. Cells spherical, 

 rod-shaped or spiral, without well-differentiated nucleus. Sulphur 

 granules and bacterio-purpurin absent. In most genera no true 

 filaments and rarely branching. Some genera produce endo- 

 spores. Conidia absent. Cells motile (by means of flagella) or 

 non-motile. Multiplication always by transverse fission. Cells 

 may be single, in chains or other grouping, and may be united 

 into gelatinous masses which are never motile nor develop cysts 

 (as in Myxobacteriales). 



Family I. NITROBACTERIACEAE. This family includes the nitri- 

 fying forms (Azotobacter, N itrosomonas , Enizobium, Nitro- 

 bacter) and acetic ferments (Acetobacter), 



Family II. PSEUDOMONADACEAE. Eod-shaped, short, usually 

 motile by means of polar flagella. No endospores. Fre- 

 quently gelatin liquefiers and usually Gram-negative. 

 Water-soluble and diffusible pigments common green, 

 blue, purple, brown or non-diffusible yellow pigment 

 (many of latter are plant parasites). 



Genus I. PSEUDOMONAS. Characters those of family. (Bacillus 

 pyocyaneus. ) 



Family III. SPIRILLACEAE. Cells elongate and more or less 

 spirillar but non-flexuous. Generally motile, with polar 

 flagella, and non-sporing. Typically water-forms. 

 Genus 1. VIBRIO. Short curved rods, motile with a single 

 (usually) polar flagellum. Non-sporing and usually Gram- 

 negative. (Cholera vibrio.) 



Genus 2. SPIRILLUM. Non-flexuous spiral cells, generally 

 motile with tuft of^flagella at one or both poles. Endospores 



