GENERAL SYSTEMATIC BACTERIOLOGY 91 



2b. Flagella tufted (5-20) 2. Spirillum 



5a. Coccaceae. 



b. Abundant red-pigmented growth on agar. 



7. Rhodococcus 

 2b. Not as above. 



c. Gram-negative. 



d. Normally in pairs of flattened cells; growth on plain agar 

 scanty, never bright yellow. 1. Neisseria 

 2d. Normally in plates, packets, or irregular masses; growth on 

 plain agar abundant, pigment definitely yellow, 

 e. Cells in regular packets.. 6. Sarcina 

 2e. Cells not in regular packets. 



5. Micrococcus 

 2c. Gram-positive (exceptions rare and not easily confused with 

 above genera). 



d. Cells normally in chains, sometimes in pairs (especially in 

 acid environment) never in large irregular masses. Gela- 

 tine rarelj^ liquefied. Growth on plain agar usually trans- 

 lucent, never heavy, never yellow or orange. 



2. Streptococcus 



2d. Cells normally in groups or masses (occasionally in plates in 

 Albococcus?) ; chains short and irregular, if present. Gel- 

 atine often liquefied. Agar growth abundant, white to 

 orange. 



e. Pigment orange (rarely lacking); gelatine often lique- 

 fied actively 3. Staphylococcus 



2e. Whitish to porcelain white; liquefaction less vigorous. 



4. Albococcus 

 6a. Bacteriaceae. 



b. Plant pathogens 2. Erwinia 



2b. Not as above; saprophytes or in animal habitats (intestines, tissues, 

 etc.) 



c. Usually motile and exhibiting active fermentative powers; 

 typically parasitic in intestines of man and higher animals; 

 growing well on ordinary media . . . 1 . Bacterium 

 2c. Not wholly as above. 



d. Growing only in presence of hemoglobin, ascitic fluid or 



serum 4. Hemophilus 



2d. Growth on media scanty, but less sensitive than the above; 

 short rods with tendency to bipolar stain. 



3. Pasteurella 

 7a. Lactobacillaceae. 



Generic characters mainly those of famih'..l. Lactobacillus 

 8a. Bacillaceae. 



b. Aerobic, usually saprophytic; cells not greatly enlarged (if at all) at 



sporulation 1. Bacillus 



2b. Anaerobic, often saprophytic; cells frequently enlarged at sporulation. 



2. Clostridium 



