FAMILY SPIROCHAETACEAE 1051 



ORDER V. SPIROCHAETALES BUCHANAN.* 



(Jour. Bact., 3, 1918, 542.) 



Slender, flexuous cell body in the form of a spiral with at least one complete turn, 

 6 to 500 microns in length. Some forms maj^ show an axial filament, a lateral crista 

 or ridge, or transverse striations; otherwise no significant protoplasmic pattern. 

 Smaller forms may have a lower refractive index than bacteria, and so living organisms 

 can be seen only with dark field illumination. Some forms take aniline dj^es with 

 difficulty. Giemsa's stain is uniformly successful. ^lultiplication by transverse 

 fission. Xo sexual cycle known. Granules formed by some species in vector hosts. 

 All forms are motile. Xo organs of locomotion**; motility serpentine or by spinning 

 on the long axis without polaritj'. Free-living, saprophytic and parasitic. 



Key to the families of order Spirochaetales. 



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



Family I. Spirochaetaceae, p. 1051. 

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



Family II. Treponemataceae, p. 1058. 



FAMILY I. SPIROCHAETACEAE SWELLENGREBEL. 



(Ann. Inst. Past., 21, 1907, 581.) 



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

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

 bivalve molluscs (Lamellibranchiata) . 



Key to the genera of family Spirochaetaceae. 



I. Xo obvious periplast membrane and no cross-striations. 



Genus I. Spirochaeta, p. 1051. 

 II. Periplast membrane present. Cross-striations prominent in stained specimens. 



A. Free -living in marine ooze. 



Genus II. Saprospira, p. 1054. 



B. Parasitic on lamellibranch molluscs. Crista prominent. 



Genus III. Cristispira, p. 1055. 



Genus I. Spirochaeta Ehrenberg. 



(Ehrenberg, Abhandl. Berl. Akad., 1833, 313; Spirochoeta Dujardin, Hist. nat. 

 des Zoophytes, 1841, 209; Spirochaete Cohn, Beitr. z. Biol. d. Pflanz., 1, Heft 1, 1872, 



* Originally prepared by Prof. D. H. Bergey, Philadelphia, Pa., October, 1922. 

 Revised by Prof. E. G. D. Murray, ]^IcGill University, Montreal, P. Q., Canada, 

 December, 1938. Further revision by Dr. G. H. Robinson, Wm. H. Singer Memorial 

 Research Laboratory of the Allegheny General Hospital, Pittsburgh, Pa., September, 

 1943. Appendices prepared by Mrs. Eleanore Heist Clise, Geneva, X. Y., Septem- 

 ber, 1943. 



** Recent photographs taken with the electron microscope indicate the presence 

 of structures resembling flagella (Mudd, Polevitzky and Anderson, Jour. Bact., 46, 

 1943, 15). Whether these can be considered as organs of locomotion awaits decision. 

 At present it seems best to confine descriptions of structure to features seen bj'^ use 

 of the oil immersion lens. 



