196 MICROBIOLOGY 



media. Perrone isolated a strictly anaerobic streptococcus 

 from the human intestinal tract. 1 



In alkaline bouillon at 37.5 C., pyogenic streptococci 

 grow rapidly, form long and tortuous chains, and have a ten- 

 dency to form flakes which rapidly sink to the bottom. 



Resistance. Streptococci on ordinary culture media, 

 without transplantation and kept at room temperature, usu- 

 ally die out within ten days to two weeks. Many of the cul- 

 tures die out in from two to three days. According to Hiss * 

 they may be kept alive for much longer periods by the use of 

 the calcium-carbonate-glucose bouillon, if the cultures are 

 thoroughly shaken and the powdered marble thoroughly mixed 

 with the bouillon from time to time. Preservation at low tem- 

 peratures (1 to 2 C.) in the ice chest considerably prolongs 

 the life of cultures. Virulence is preserved longest by frequent 

 transplantation upon albuminous media. In sputum or animal 

 excreta, streptococci may remain alive for several weeks. 



Streptococci are killed by exposure to a temperature of 

 54 C. for ten minutes. 2 Low temperatures, and even freezing, 

 do not destroy some races. Some species seem to resist a tem- 

 perature somewhat higher than 54 C. 



The action of various chemical disinfectants has been 

 thoroughly investigated by v. Lingelsheim, 3 who reports among 

 others the following results : Carbolic acid 1 : 200 kills strep- 

 tococci in fifteen minutes. In the same time, bichloride of 

 mercury is efficient in a dilution of 1 : 1,500 ; lysol in a dilution 

 of 1 : 200 ; peroxide of hydrogen 1 : 35 ; sulphuric acid 1 : 150 

 and hydrochloric acid 1 : 150. Inhibition is exerted by carbolic 

 acid 1 : 550 ; and by bichloride of mercury 1 : 65,000. Exposure 

 to direct sunlight kills streptococci in a few hours. 



1 Perrone. Ann. de 1'Inst. Pasteur, Vol. XIX (1905) p. 367. 

 * Hiss, loc cit. 



2 Sternberg. Textbook of Bacteriology, 2d. ed., 1901. Hartmann 

 Arch. f. Hyg., Bd. VII (1887) p. 83. 



3 v. Lingelsheim. Beit. z. Exper. Therap., Abt. I (1899) p. 1. 



