1002 COMPREHENSIVE KEY 



Organisms arranged singly, in pairs and in irregular clusters; rarely in chains 



Peptococciis p. l^^l^. 

 Note: Peptococcus constellatus may belong to Peptostrepiococcus. 



23. Gram-negative, kidney-shaped to hemispherical cells occurring basically in pairs with 



the flat sides adjacent; animal parasites Neisseria p. 4S0 



Note: Micrococcus morrhuae and M. roseus are described as Gram-negative 

 occurring singly and in pairs. 

 Not as above 24 



24. Organisms arranged in cubical packets Sarcina p. Ifil 



Organisms from liquids are arranged singly, in pairs or as tetrads and occasionally 



in short chains; tetrads common in acid media; produce at least 0.5 to 0.7 per cent 

 acid in yeast-extract-glucose-tryptose-phosphate broth, lowering the pH below 4.0; 

 lactic acid produced is optically inactive; found in fermented liquids and foods 



Pediocoecus p. 529 

 Not as above 25 



25. Organisms arranged in pairs only or in chains of varying lengths when growing in liquid 



media 26 



Organisms arranged singly, in pairs and in clusters in liquid media; occasional species 

 are motile 28 



26. Organisms produce gas in Eldredge tubes when growing in yeast-extract-glucose-tryp- 



tose-phosphate broth; lactic acid produced is levo -rotatory; frequently produce a 



copious slime (dextran) in sucrose broth Leuconostoe p. 531 



Not as above; lactic acid produced is dextro-rotatory 27 



27. Parasitic; cells usually in pairs, particularly in pathological material, where they are 



encapsulated; chains are common in culture media; bile-soluble; found in the respira- 

 tory tract of man Diplococcus p. 507 



Other than above; parasitic or saprophytic Streptococcus p. 508 



28. Cells occur predominantly as tetrads and are encapsulated in body fluids; occur as 



tetrads and in irregular masses in cultures Gaffkya p. ^66 



Not as above Micrococcus p. 1^.55 



Staphylococcus p. Ifil^ 

 Note: Placed in the genus Staphylococcus are two species, Staphylococcus aureus 

 and Staphylococcus epidermidis. Reference should be made to the species de- 

 scriptions for separation from the other micrococci. 



29. Cell masses are green or yellowish green; probably contain chlorobium chlorophyll 



and not bacteriochlorophyll 30 



Cell masses red or purple; proceed to Section J p. 1031 



30. Spherical to ovoid cells occurring in chains and forming flat sheets in which the chains 



are parallel. Oxidize hydrogen sulfide but do not store sulfur inside the cells 



Pelodictyon p. 63 

 Spherical cells united in loose trellis-like aggregates. Sulfur is deposited internally 



Clathrochloris p. 64 



