436 GENERAL SYSTEMATIC BACTERIOLOGY 



Winslow et al. (Committee Soc. Am. Bact., 1917, p. 556) used the 

 following generic description. 



Rod-shaped, short, usually motile by means of polar flagella or rarely non- 

 motile. Aerobic and facultative. Frequently gelatin liquefiers and active 

 ammonifiers. No endospores. Gram stain variable, though usually negative. 

 Fermentation of carbohydrates as a rule not active. Frequently producing a 

 water-soluble pigment which diffuses through the medium as green, blue, purple, 

 brown, etc. In some cases a non-diffusible yellow pigment is formed. Many 

 yellow species are plant parasites. 



Buchanan (1918, p. 48) discussed at length the nomenclatural status 

 of the genus, and gave the following description. 



Rod-shaped bacteria, never spiral, usually motile by means of polar flagella or 

 rarely non-motile. Aerobic and facultative. Frequently liquefying gelatin. 

 Without spores. Gram stain variable. Usually producing a water-soluble pig- 

 ment which diffuses through the medium as a green, blue, purple, or brown or in 

 some cases a yellow pigment. Fermentation of carbohydrates usually not active. 



The type species is Pseudomonas aeruginosa (Schroter) Frost? 



Later Winslow et al. (1902, p. 204) designated the type species as 

 Ps. aeruginosa (Schroter) Frost? Enlows (1920, p. 74) states, '^Type 

 species (monotype) — Pseudomonas violacea (Schroter 1886) Migula." 

 This designation can be made only by reference to Migula's publica- 

 tions after the first in which Pseudomonas was proposed. There had 

 been previously described: 



Pediococcus violaceus Trevisan 1889 

 Lampropedia violacea Trevisan 1889 

 Thiocystis violacea Winogradsky 1889 

 Spirillum violaceum Warming 

 Bacteridium (Bacillus) violaceum Schroter 

 Chromobacterium violaceum Bergonzini 

 Chromococcus violaceus Bergonzini 

 Micrococcus violaceus Cohn 

 Streptococcus violaceus (Cohn) Trevisan 



Migula (1895) particularly emphasizes the fluorescent pigment 

 production as characteristic. The first species described is one which 

 is typical and should be designated as the type as was done by Winslow 

 et al. 



Bergey et al. (1923, p. 122) include Pseudomonas as the fourth genus 

 of the tribe Chromohadereae with the following description: "Princi- 

 pally water and soil bacteria producing a water-soluble pigment which 



