GRAM-NEGATIVE COCCI 



387 



with 24 hours. Cultures from the nose and throat, however, produce 

 acid and coagulation, or else produce an alkaline reaction. 



OTHER GRAM-NEGATIVE COCCI 



Micrococcus pharyngis siccus. First described by von Lingelsheim 1 

 in 1906. It is described by Elser and Huntoon as readily differentiable 

 from meningococcus and other Gram-negative cocci by the firm adher- 

 ence and dryness of its colonies. It is similar to Micrococcus catarrhalis 

 from which it may, however, be differentiated by fermentation tests. 



Diplococcus mucosus. This organism was also described by von 

 Lingelsheim together with the preceding one. Its colony formation is 

 similar to that of meningococcus, but slightly more sticky and mucoid. 

 Stained by the capsule methods, it is seen to possess a distinct capsule. 



Chromogenic Gram-negative Cocci. These microorganisms all pro- 

 duce a greenish-yellow pigment on the ordinary culture media. When 

 pigment is absent, as is frequently the case when grown upon sugar-free 

 media, these microorganisms can be distinguished from meningococcus 

 only by sugar fermentation and serum reactions. 



An exhaustive study of Gram-negative micrococci has recently been 

 made by Elser and Huntoon. 2 These authors, in studying the differ- 

 ential value of sugar fermentation in the diagnosis of these bacteria, 

 have constructed the following table: 



v. Lingelsheim, Klin. Jahrb., 15, 1906, 



2 Elser and Huntoon, loc. cit. 



