CLASSIFICATION OF BACTERIA. 41 
3. Family SPIRILLACE#, curved, rod-shaped 
forms without envelope. . 
Genus > 
1. Spivosoma, non-motile; cells rigid. 
2. Microspira, motile; one, rarely two or three, 
polar flagella. 
3. Spirvillum, motile ; polar tufts of flagella. 
4. Spirocheta, cells flexile. 
4. Family CHLAMYDOBACTERIACE®, cells with 
envelopes. 
Genus: 
1. Chlamydothrix, unbranched threads ; cell-division 
in one plane. 
2. Crenothrix, unbranched threads ; cell-division 
in three planes ; sheath visible. 
3. Phragmidiothrix, unbranched threads ; cell-division 
in three planes ; sheath scarcely 
visible. 
4. Spherotilus, branched threads. 
THIOBACTERIA, Cells contain sulphur granules or 
bacterio-purpurin ; red or violet color, never green. 
1. Family BEGGIATOACE&, thread-forming, with- 
out bacterio-purpurin. 
Genus: 
1. Thiotrix, attached threads ; non-motile. 
2. Beggiatoa, unattached threads; motile. 
2. Family RHODOBACTERIACE, cells contain 
bacterio-pupurin and sulphur granules; red or 
violet. 
