42 



(2) Cells crooked, without sheath 3. Spirillaceae. 



(3) Cells enclosed in a sheath ...4. Chlamydobacteriaceae. 



(4) Cells destitute of a sheath, united into 

 threads, motile by means of an undu- 

 lating membrane 5. Beggiatoaceae. 



GENERA. 



/. Coccaceae. 



Cells without organs of motion. 



a. Division in one plane i. Streptococcus. 



b. Division in two planes - 2. Micrococcus. 



c. Division in three planes 3. Sarcina. 



Cells with organs of motion. 



a. Division in two planes 4. Planococcus. 



b. Division in three planes 5. Planosarcina. 



2. Bacteriaceae. 



Cells without organs of motion i. Bacterium. 



Cells with organs of motion (flagella). 



a. Flagella distributed over the whole 



body 2. Bacillus. 



b. Flagella polar 3. Pseudomonas. 



3. Spirillaceae. 



Cells rigid, not snake-like or flexuous. 



a. Cells without organs of motion i. Spirosoma. 



b. Cells with organs of motion ( flagella ) . 



1. Cells with I, very rarely 2-3 polar 



flagella 2. Microspira. 



2. Cells with polar flagella-tufts 3. Spirillum. 



Cells flexuous 4. Spirochaeta. 



4.. Chlamydobacteriaceae. 



Cell contents without granules of sulphur. 



a. Cell threads unbranched. 



I. Cell division always only in one plane i. Streptothrix. 



II. Cell division in three planes previous to 

 the formation of conidia. 



1. Cells surrounded by a very delicate, 



scarcely visible sheath (marine) 2. Phragmidiothrix. 



2. Sheath clearly visible (in fresh water)_3. Crenothrix. 



b. Cell threads branched 4. Cladothrix. 



Cell contents containing sulphur granules_5. Thiothrix, 



