GENERAL SYSTEMATIC BACTERIOLOGY 89 



E. Organisms intermediate between bacteria and protozoa. 



1. Genus. Spirochaeta. 



2. Genus. Cristispira. 



3. Genus. Saprospira. 



4. Genus. Treponema. 



An artificial key to the orders and genera was also published as 

 follows : 



1. Artificial Key to the Orders of the Schizomycetes 



a. Cells united during the vegetative stage into a pseudoplasmodium. 



A. Myxobacteriales 

 2a. Cells not forming a pseudoplasmodium. 



b. Cells free or united in elongated filaments, often with a well-defined 

 sheath. Conidia frequently formed. Free sulphur, iron or bacterio- 

 purpurin often present. 

 c. Cells typically containing granules of sulphur or bacteriopur- 



purin or both B. Thiobacteriales 



2c. Sulphur and bacteriopurpurin absent; iron often present. 



C. Chlamydobacteriales 

 2b. Cells never in sheathed filaments. Conidia only in the mycelial 

 Mycobacteriaceae. Flagella often present. Free iron, sulphur, or 

 bacteriopurpurin never present D. Eubacteriales 



2. Artificial Key to the Families of the Eubacteriales 



a. Cells spiral with polar flagella IV. Spirillaceae 



2a. Not^as above. 



b. Cells spherical; rarely, if ever, motile; spores never produced; never 

 securing growth energy from nitrogen or ammonia. 



V. Coccaceae 

 2b. Not as above. 



c. Cells short rod-shaped with a single (rarely two) polar flagellum; 

 usually forming green or yellow pigment. 



III. Pseudomonadaceae 

 2c. Not wholly as above. 



d. Spores formed VIII. Bacillaceae 



2d. Spores never formed. 



e. Metabolism simple, securing growth energy from car- 

 bon, hydrogen, or their simple compounds; flagella, 



if present, polar I. Nitrobacteriaceae 



2e. Metabolism complex, dependent upon more complex 

 carbohydrate and protein substances; flagella, if 

 present, peritrichic. 



f. Cells clubbed, fusiform, filamentous, branching or 

 mycelial; those not distinctly so are either acid- 

 fast or show barred irregular staining. 

 II. Mycobacteriaceae 



