FORM AND STRUCTURE OF BACTERIA 



21 



length, and from 0.2 to 4 microns in width, according to 

 the species. 



The spirilla are motile, usually possessing flagella at one or 

 both poles. The common method of locomotion through a 

 medium is by rotation on the long axis, attended in the case 

 of spirochaetes by some lateral motion. 

 The flagella or flagellum precedes the cell 

 when in motion. A few motile spirilla 

 do not possess any flagella. 



Most spirilla do not produce spores. 

 The method of reproduction among this 

 group of bacteria is by fission, being simi- 

 lar in this respect to the cocci and the 

 bacilli. 



Trichobacteria or Higher Bacteria. 

 The trichobacteria or higher bacteria con- 

 sist of filaments of varying length. The 

 filaments show both true and false branch- 

 ing. The filament can by special stains 

 be shown to be made up of individual cells 



separated from each other by definite 



FIG. 15. Cladothrix 



septa. Frequently all the individual cells dichotoma. Show- 

 ing "false "branch- 

 in the filament are surrounded by a com- 

 mon sheath or membrane (Fig. 15) (see 

 infra j Sheaths). Certain cells at one end 

 of the filament are used to attach the filament to other fila- 

 ments and to various objects. At the free end of the filament 



ing typical of tri- 

 chobacteria. After 

 Schmidt and Weis. 



