GENERIC CHARACTERS IN THE COCCACEAE 205 



well under anaerobic conditions. Many forms fail to grow on 

 artificial media; none produce very abundant surface growths. 

 Planes of fission often parallel, producing pairs, or short or long 

 chains, never packets. Generally stain by Gram. Produce acid 

 in dextrose and lactose broth. Pigment, if any, white or orange. 



Genus i, Diplococcus (Weichselbaum) : Strict parasites. Not 

 growing, or growing very poorly, on artificial media. Cells nor- 

 mally in pairs surrounded by a capsule. Includes D. pneumoniae 

 Weich, D. Weichselbaumii Trev., and D. gonorrheae Neisser. 



Genus 2. Streptococcus (Billroth) : Parasites (see above). Cells 

 normally in short or long chains (under unfavorable cultural condi- 

 tions, sometimes in pairs and small groups, never in large packets). 

 Generally stain by Gram. On agar streak effused, translucent growth, 

 often with isolated colonies. In stab culture, little surface growth. 

 Sugars fermented with formation of large amount of acid. Generally 

 fail to liquefy gelatin or reduce nitrates. Includes S. erysipelatos 

 Fehleisen. 



Genus 3, Aurococcus, new genus: Parasites (see above). Cells 

 in groups and short chains, very rarely in packets. Generally stain 

 by Gram. On agar streak good growth of orange color. Sugars 

 fermented with formation of small amount of acid. Gelatin often 

 liquefied, very actively. May or may not reduce nitrates. Includes 

 A. aureus (Rosenbach). 



Genus 4, Albococcus, new genus: Parasites (see above). Cells 

 in groups and short chains (never in packets). Generally stain by 

 Gram. Growth on agar streak abundant and porcelain white in 

 color. Sugars fermented with production of a slight amount of 

 acid. Gelatin liquefaction and nitrate reduction may or may not 

 occur. Includes A. pyo genes (Rosenbach), A. rhenanus (Migula), 

 A. candicans (Fliigge), and A. canescens (Migula). 



Subfamily 2, Metacoccaceae (W. and R.): 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 

 zooglea masses. Generally decolorize by Gram. Pigment, yellow or 

 red. 



Genus 5, Micrococcus (Hallier): Facultative parasites or sapro- 



