80 GENERAL SYSTEMATIC BACTERIOLOGY 



present. A sheath usually evident, and usually 

 impregnated with iron. 



Order II. Chlamydobacteriales 

 (b) Mold like, not typically water forms, not with the 

 sheath impregnated with iron. True branching 

 often evident. 



Order III. Actinomycetales 

 b. Cells typically containing either granules of free sulphur or 

 bacteriopurpurin or both, usually growing best in the presence 

 of hydrogen sulphid. 



Order IV. Thiobacteriales 

 II. Cells united during the vegetative stage into a pseudoplasmodium 

 which passes over into a highly developed, cyst-producing, resting 



stage Order V. Myxobacteriales 



B. Protozoan-like in many characters. Cells usually relatively slender flexuous 

 spirals; multiplication of cells apparently by longitudinal division in some 

 types, by transverse division in others, or both. 



Order VI. Spirochaetales 



Key to the families of the Eubacteriales 



A. Organisms usually growing more or less readily upon organic media, not 



securing growth energy primarily by the oxidation of ammonia or nitrites. 

 I. Cells typically spherical. .Family I. Coccaceae 

 II. Cells not spherical, elongate. 



a. Cells not spiral Family II. Bacteriaceae 



b. Cells spiral, or at least curved. 



Family III. Spirillaceae 



B. Not growing readily or at all on media containing considerable amounts of 



organic material; nitrifying bacteria, securing growth energy primarily by 

 the oxidation of ammonia or nitrites. 

 Cells may be either spherical or rod-shaped. 



Family IV. Nitrobacteriaceae 



Key to tribes of the Coccaceae 



1. Not epiphytes, not causing the deposition of iron upon capsules. 



A. Commonly parasitic, in some forms saprophytic, usually thriving well 



under anaerobic conditions, not commonly producing luxuriant 

 growths on artificial media, many forms failing to grow except upon 

 special media. Cells in pairs, chains or irregular masses, never 

 regular packets. Gram-positive, with exception of a few strict 

 parasites. Acid usually formed in dextrose and lactose broth. 

 Pigment white, orange or absent. 



Tribe I. Streptococceae 



B. Saprophytes, or facultative parasites. Usually grow best under aerobic 



conditions, producing abundant to luxuriant growth on artificial 

 media. Planes of fission often at right angles: Cells aggregated in 

 groups, packets or zoogloeal masses. Usually Gram-negative. 

 Pigment as a rule yellow, red or orange. 



Tribe II. Micrococceae 



