ORDER IX. SPIROCHAETALES BUCHANAN, 1918. 



(Jour. Bact., 3, 1918, 5-12.) 



Spi.ro.chae. tales. M.L. fem.n. Spirochaeta type genus of the order; -ales ending to de- 

 note an order; M.L. fem.pl.n. Spirochaetales the Spirochaeta order. 



Slender, flexuous bodies, 6 to 500 microns in length, in the form of spirals with at least 

 one complete turn. Some forms may show an axial filament, a lateral crista, or ridge, or 

 transverse striations; otherwise there is no significant protoplasmic pattern. Smaller forms 

 may have a lower refractive index than that of true bacteria, and therefore they can be seen 

 :)nly with dark-field illumination. Some forms take aniline dyes with diflficulty; Giemsa's 

 stain is uniformly successful. Granules are formed in some species which are found in vec- 

 tor hosts. All forms are motile. In the true bacteria, motility is effected by flagella endowed 

 with a lashing movement; however, no such structures exist among the spirochetes. Ter- 

 minal projections, whether derived from the periplast or from the axial filament, may assist 

 in the movements, and it is possible that the crista has a similar function, although neither 

 of these structures can explain the violent motion of the spirochetes. This motility con- 

 sists of a rapid whirling or spinning about the long axis, which activity drives the organ- 

 ism forward or backward, there being no anteroposterior polarity. In addition the spiro- 

 chetes make violent, lashing movements, curling and uncurling their spirals. Multiplica- 

 tion is by transverse fission, no sexual cycle being known. Free-living, saprophytic and 

 parasitic forms. 



Key to the families of order Spirochaetales. 



I. Spirals 30 to 500 microns in length, possessing definite protoplasmic structures. 



Family I. Spirochaetaceae, p. 892. 

 II. Spirals 4 to 16 microns in length, possessing no obvious protoplasmic structure. 



Family II. Treponemataceae, p. 896. 



FAMILY I. SPIROCHAETACEAE SWELLENGREBEL, 1907. 



(Ann. Inst. Past., £1, 1907, 581.) 



Spi.ro. chae.ta'ce.ae. M.L. fem.n. Spirochaeta type genus of the family; -aceae ending to 

 denote a family; M.L. fem.pl.n. Spirochaetaceae the Spirochaeta family. 



Coarse, spiral organisms, 30 to 500 microns in length, possessing definite protoplasmic 

 structures. Found in stagnant, fresh or salt water and in the intestinal tracts of bivalve 

 molluscs (Lamellibranchiata) . 



* Revised by Dr. G. H. Robinson, Wm. H. Singer Memorial Research Laboratory of the 

 Allegheny General Hospital, Pittsburgh, Pa., September, 1943; further revision by Dr. 

 Gordon E. Davis, Rocky Mountain Laboratory, U. S. Public Health Service, Hamilton, 

 Montana, assisted by Mrs. Elsie Wattie Lackey (Family Spirochaetaceae), University of 

 Florida, Gainesville, Florida, May, 1955. 



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