222 PUBLIC HEALTH BACTERIOLOGY 



60 C. for one hour ; inject 100 to 250 million of the dead 

 staphylococci, repeating in 3 to 4 days later ; opsonins 

 increased. 



Habitat. Skin and mucous surfaces. 



Differentiation: (Gordon). Staphylococcus pyogenes 

 aureus clots milk, liquefies gelatin, at times produces 

 green fluorescence in neutral red broth, reduces nitrates 

 to nitrites, produces acid in Lemco media containing 

 maltose, lactose, glycerin, and mannite. Staphylococcus 

 epidermidis albus gives the same reactions, except that it 

 does not produce acid with mannite. 



Houston's Lemco Medium : consists of distilled water 

 containing i per cent of Lemco, i per cent of peptone, 

 o-i per cent of sodium bicarbonate, and litmus solution 

 to colour. Add i per cent of test substance (carbo- 

 hydrate, etc.). 



STREPTOCOCCI. 



Ogston in 1881 first differentiated between the 

 irregularly grouped staphylococci and the chain cocci 

 or streptococci. Pure cultures were first obtained by 

 Fehleisen in 1883 and Rosenbach in 1884. Named from 

 tendency to form chains, and so the group includes 

 micro-organisms which differ considerably from each 

 other in cultural and pathogenic characters. The strep- 

 tococci pathogenic to man mostly form chains of eight 

 or more individual cocci, while the saprophytic varieties 

 are apt to be united in shorter groups. On this basis 

 streptococci have been divided into S. longi and S. breves, 

 but the distinction is not a reliable one. Similarly, 

 the streptococcus of ordinary pus formation was thought 

 to be different from that of erysipelas. This is now proved 

 not to be the case, and the two are regarded as one and the 

 same. These statements enable one to attach the proper 

 significance to the various names used ; to wit : S. pyogenes, 

 S. erysipelatis, S. longus, S. brevis. S. conglomeratus is a 

 variety, and is so called from its forming in broth culture 

 minute granules composed of very long chains (identical 

 with S. anginosus or scarlatinae). Streptococci grow well 

 on all the richer media, and better in broth made from meat 

 or veal than from meat extract. Animal serum and 



