86 GENERAL SYSTEMATIC BACTERIOLOGY 



Keij to the Genera of the Thiocapseae 



A. Cells capable of swarming. 



I. Families small, compact, enclosed singly or several together in a cj'st. 



Genus I. Thiocijstis 

 II. Cells large, 7 to 8/^, loosely bound by gelatin into loose families. 



Genus II. Thiosphaera 

 III. Cells small, united into solid, spherical families. 



Genus III. Thiosphaerion 



B. Cells not capable of swarming. 



I. Spherical cells spread out upon the substratum in flat families, loosely 

 enveloped in a common gelatin. 



Genus IV. Thiocapsa 

 II. Arranged in regular packets like Sarcina. 



Genus V. Thiosarcina 



Key to the Genera of Lamprocysteae 



One genus only: Lamprocystis. 



Key to the Genera of Thiopedieae 



A. Cells occurring regularly in fours. . . .Genus I. Lampropedia 



B. Cells occurring in a film or membrane, not regularly disposed in tetrads. 



Genus II. Thioderma 



Key to the Genera of Amoebobacterieae 



I. Cells connected by plasma threads, families amoeboid motile. 



Genus I. Amoebobacter 



II. Cells not as I. 



A. Cells arranged in a net, united by their ends. 



Genus II. Thiodictyon 



B. Cells not arranged in a net. 



1. Capable of swarming. Cells loosely aggregated in gelatin. 



Genus III. Thiothece 



2. Non-motile. Cells closely appressed into a colony. 



Genus IV. Thiopoly coccus 



Key to the Genera of Chromatieae 



A, Cells motile by means of polar flagella. Elongated. 



I. Cells not spiral. 



a. Cell cylindric Genus I. Chromatium 



b. Cells with tendency to spindle shape. 



Genus II. Rhabodomonas 

 II. Cells spiral Genus III. Thiospirillum 



B, Cells spherical, or little elongate, non-motile. 



I. Cells not encapsulated Genus IV. Rhodocapsa 



II. Cells encapsulated in pairs. . .Genus V. Rhodothece 



Key to the Genera of Rhodobacterioideae 



A. Cells rod shaped, many embedded in the same slimy capsule. 



Genus I. Rhodocystis 



