RELATION TO ENVIRONMENT CLASSIFICATION 37 



Genus V. Planosarcina. Cells divide in three directions of space as in 

 sarcina, but possess flagella. 



FAMILY II. BACTERIACE^E. Cells long or short, cylindrical, straight, never 

 spiral. Division in one direction of space only, after preliminary elonga- 

 tion of the rods. 



Genus I. Bacterium. Cells without flagella, often with endospores. 

 Genus II. Bacillus. Cells with peritrichal flagella,. of ten with endospores. ' 

 Genus HI. Pseudomonas. Cells with polar flagella. Endospores occur 

 in a few species, but are rare. 



FAMILY III. SPIRILLACE^. Cells spirally curved or representing a part of a 

 spiral curve. Division in one direction of space only, after preceding 

 elongation of cell. 



Genus I. Spirosoma. Cells without organs of locomotion. Rigid. 



Genus II. Microspira. Cells rigid, with one or, more rarely, two or three 

 polar undulated flagella. 



Genus III. Spirillum. Cells rigid, with polar tufts of five to twenty 



flagella usually curved in semicircular or flatly undulating curves. 



Genus IV. Spirochcete. Cells sinously flexible. Organs of locomotion un- 

 known, perhaps a marginal undulating membrane. 



FAMILY IV. CHLAMYDOBACTERIACEVE. Forms of varying stages of evolution, 

 all possessing a rigid sheath (Hiille), which surrounds the cells. Cells 

 united in branched or unbranched threads. 



Genus I. Streptothrix. Cells united in simple, unbranched threads. Divi- 

 sion in one direction of space only. Reproduction by non-motile 

 conidia. 



Genus II. Cladothrix. Cells united or pseudodichotomously branching 

 threads. Division in one direction of space only. Vegetative multipli- 

 cation by separation of entire branches. Reproduction by swarming 

 forms with polar flagella. 



Genus III. Crenothrix. Cells united in unbranched threads, at first with 

 division in one direction of space only. Later the cells divide in all three 

 directions of space. The daughter cells become rounded and develop 

 into reproductive cells. 



Genus IV. Phragmidiothrix. Cells at first united in unbranched threads, 

 dividing in three directions of space, thus forming a rope of cells. Later 

 some of the cells may penetrate through sheath, and thus give rise to 

 branches. 



