178 R. E. BUCHANAN 



The following genera are probably not invalid for any of the 

 preceding reasons. 



Liquidovihrio, Microspira, Pacinia, Paraspirillium, Solido- 

 vibrio, Spirillu7n, Spirosoma, Vibrio. 



The following key will serve to differentiate the genera which 

 may be recognized at present. 



Key to genera of Spirillaceae 



A. Cells not larger at center, not tapering. 



1. Cells usually short, only a segment of a spiral. One or rarely 



two or three polar flagella Genus 1. Vibrio 



2. Cells longer, usually with a tuft of polar flagella. 



Genus 2. Spirillum 



B. Cells enlarged at center and tapering Genus 3. Paraspirillum 



Genus 1. Vibrio Mueller, 1786 p. 39 emended 



Synonyms 



Pacinia Trevisan, 1885, p. 83 



Pseudospira De Toni and Trevisan, 1889, p. 1018 



Microspira Schroeter, 1886, p. 168 



Liquidovihrio Jensen, 1909, p. 333 



Solidovihrio Jensen, 1909, p. 333 

 Short, bent rods, sometimes almost straight. Motile by means 

 of a single {rarely 2 or 3) polar flagellum. Aerobic, and faculta-' 

 tive. Grow well on ordinary media. Frequently liquefy gelatin. 

 Not enlarged near center. No spores. Usually gra7n negative. 



The type species is Vibrio cholerae. The generic name Vibrio 

 has been used in several senses by different writers. Most of 

 the species included in this genus by writers before the time of 

 Cohn are now definitely placed in other genera or cannot be 

 identified. Pacini (1851) used the designation Vibrioni of 

 cholera, though it is not certain that he actually saw the organism 

 causing the disease. 



The Vibrio of Miiller was any very simple, ''terete, elongate 

 worm." Ehrenberg (1838) defined the genus to include straight 

 flexuous rods. Cohn (1872, p. 178) emended the genus to 

 include organisms characterized by a wavy motion of the fila- 



