GENERAL SYSTEMATIC BACTERIOLOGY 83 



Key to the genera of Bacteriinae 



A. Producing usually a yellowish or greenish or fluorescent pigment, usually 



Gram-negative, motile by means of polar flagella, or non-motile. 



Genus 1. Pseudomonas 



B. When pigmented not greenish or fluorescent, when motile with peritrichoua 



flagella. 



1. Cells typically pigmented, chromoparous. 



a. Producing red or pink pigment. 



Genus 2. Serratia 



b. Producing a violet pigment. 



Genus 3. Chromohacterium 



2. Cells not typically definitely pigmented, or at least not red or violet. 



a. Cells typically Gram-negative. 



(1) Non-motile, showing bipolar staining commonly. Never produce 



gas from carbohydrates. Power of acid production low. 

 Genus 4. PasteureUa 



(2) Not showing bipolar staining. 



(a) Not producing honej^-like growth on potato, branching 



forms uncommon. 

 X. Gelatinnot liquefied or liquefied very slowly. Motile 

 or non-motile. 



Genus 5. Bacterium 

 XX. Gelatin liquefied quickly. Motile. 

 Genus 6. Proteus 



(b) Producing a honey-like growth on potato. Branched cells 



not uncommon. Genus 7. Pfeifferella 



b. Cells typically Gram-positive. All non-motile. 



(1) Usually microaerophilic. Not typically growing well on the 



surface of laboratory media. Without metachromatic 

 granules. 



(a) Non-pathogenic lactic acid bacilli. 



Genus 8. Lactobacillus 



(b) Pathogenic, slender, small rods, not lactic acid formers. 



Genus 9. Erysipelothrix 



(2) Aerobic rods, frequently showing metachromatic granules 



or irregular staining. .Genus 10. Corynebacteriuni 



Key to the subgenera of Bacterium 



A. Organisms which show a maximum of fermentative power, including fermenta- 



tion of lactose, rarely pathogenic, some forms slowly liquefy gelatin. 



Subgenus 1. Aerobacter (or Eu-Bacterium) 



B. Organisms not showing maximum fermentative power, never producing gas in 



lactose, frequently pathogenic, never liquefying gelatin. 



1. Producing acid and gas from glucose, sometimes other sugars, but none 



from lactose Subgenus 2. Salmonella 



2. Producing gas from none of the carbohydrates, acid sometimes formed. 



Subgenus 3. Eberthella 



