CLASSIFICATION OF BACTERIA 55 



mentative powers high, most strains forming acid in glucose, lactose, 

 sucrose, and inulin. Type species, D. pneumonice Weichselbaum. 



Genus 3. Leuconostoc. Saprophytes usually growing in cane 

 sugar solutions. Cells in chains or pairs united in large zoogleal 

 masses. Some types at least Gram-negative. Type species L. 

 m e s enter old es (Cienkowski) van Tieghem. 



Genus 4. Streptococcus. Chiefly parasites. Cells normally in 

 short or long chains (under unfavorable conditions sometimes in 

 pairs and small groups, never in, large packets) . Generally stain by 

 Gram. Capsules rarely present, no zoogleal masses. On agar 

 streak, efl'used translucent growth often with isolated colonies. In 

 stab culture little surface growth. Many sugars fermented with 

 formation of large amount of acid, but inulin is rarely attacked. 

 Generally fail to liquefy gelatin or reduce nitrates. Type species, 

 S. pyogenes Rosenbach. 



Genus 5. Staphylococcus. Parasites. Cells in groups and short 

 chains, very rarely in packets. Generally stain by Gram. On agar 

 streak good growth, of white or orange color. Glucose, maltose, 

 sucrose, and often lactose, fermented with formation of moderate 

 amount of acid. Gelatin often liquefied very actively. Type species, 

 S. aureus Rosenbach. 



Tribe C.Micrococcece. Facultative parasites or saprophytes. 

 Thrive best under aerobic conditions. Grow well on artificial media, 

 producing abundant surface growths. Planes of fission often at 

 right angles; cell aggregates in groups, packets, or zoogleal masses. 

 Generally decolorize by Gram. Pigment yellow or red. 



Genus 6. Micrococcus. Facultative parasites or saprophytes. 

 Cells in plates or irregular masses (never in long chains or packets). 

 Generally decolorize by Gram. Growth on agar abundant, with 

 formation of yellow pigment. Glucose broth slightly acid, lactose 

 broth generally neutral. Oelatin frequently liquefied, but not 

 rapidly. Type species, M. luteus (Schroeter) 1872b, Cohn. 



Genus 7.Sarcina.Sarcina differs from Micrococcus solely in 

 the fact that cell division occurs under favorable conditions in three 

 planes, forming regular packets. Type species, Sarcina ventriculi 

 Goodsir. 



Genus 8. Rhodococcus. Saprophytes. Cells in groups or regular 

 packets. Generally decolorize by Gram. Growth on agar abundant 

 with formation of red pigment. Glucose broth slightly acid, lactose 

 broth neutral. Gelatin rarely liquefied. Nitrates generally reduced. 

 Type species, R. rhodochrous Zopf . 



FAMILY V.Bacteriacece. Rod-shaped cells without endospores. 

 Usually Gram-negative. Flagella when present peri trichic. Metab- 

 olism complex, amino-acids being utilized and generally carbo- 

 hydrates. 



