234 A MANUAL OF BACTERIOLOGY 



the surrounding medium ; the gelatin is not liquefied. 

 In broth a flocculent deposit forms, the fluid sometimes 

 remaining clear, sometimes becoming turbid. There is 

 no growth on potato. Litmus milk is usually acidified 

 and sometimes coagulated, and acid is generally produced 

 from glucose. The indole reaction can be obtained in 

 broth cultures in seven to fourteen days on the addition 

 of a nitrite, but not without. It is the only organism with 

 which the writer is acquainted that does not reduce a weak 

 solution of methylene blue. 



The thermal death-point of the streptococci is 53 to 

 55 C., the time of exposure being ten minutes, and they 

 are destroyed by weak solutions of disinfectants, e.g. 

 1-100 phenol, in ten minutes. 



Considerable attention has been directed to the dif- 

 ferentiation of streptococci by Houston, 1 Andrewes, 2 

 Andrewes and Horder, 3 Gordon, 4 and Besredka. Con- 

 siderable differences are found in the fermentation re- 

 actions of various strains of streptococci, and Andrewes 

 and Horder distinguish (1) Streptococcus pyogenes from 

 pus, erysipelas, cellulitis, pya3mia and septicaemia, endo- 

 carditis, etc. (2) S. salivarius, the common type in the 

 saliva. Also met with, probably as a " terminal " infec- 

 tion, in endocarditis and septicaemia. Shades into the 

 S. fcecalis and S. anginosus. (3) S. anginosus, from 

 inflamed and scarlatina throats, endocarditis, and rheu- 

 mati^m. (4) S. fcecalis, abundant in faeces, air, and dust. 

 Met with also in endocarditis, meningitis, cystitis, and 

 suppuration. Two strains of the Diplococcus rheumaticus 

 proved to be this organism. (5) The pneumococcus. 



1 Rep. Ned. Off. Loc. Oov. Board for 1902-03, p. 511, and 1903-04, 

 p. 472. 



2 Lancet, November 24, 1906. 



3 Ibid. 1906, vol. ii, pp. 708, 775, 852. 



4 Ibid. November 11, 1905, and Rep. Med. Off. Loc. Gov Board 

 for 1903-04, p. 388. 



