326 J. HOWAED MUELLER 



portion of 1 pound meat to 500 cc. tap water, heating slowly to 

 boiling, straining and filtering, was boiled for twenty-five min- 

 utes with 10 per cent "Norit," a commercial grade of wood char- 

 coal used in sugar refining. The mixture was filtered through 

 paper, and the colorless filtrate used in the preparation of the 

 following media: 



■J . fDecolorized infusion 25 cc. 



\Glucose-SaIt solution 25 cc. 



Lot 2 Same plus peptone ("Difco") .5 gm. 



. „ fOriginal heart infusion 25 cc. 



\Glucose-salt solution 25 cc. 



Lot 4 Same plus peptone .5 gm. 



fWater 25 cc. 



Lot 5 < Glucose-salt solution 25 cc. 



[Peptone 0.5 gm. 



Each lot was brought to pH of 7.4 to 7.8, filtered if necessary, 

 tubed and sterihzed at ten pounds steam pressure for ten minutes. 



It is evident from this experiment, that beef heart infusion, 

 prepared as described above, constitutes a perfectly satisfactory 

 medium for the strain of streptococcus used, without the addi- 

 tion of peptone. Peptone water alone, moreover, even when 

 suppUed with glucose and an inorganic salt mixture will not 

 support growth of the organism. When the infusion has been 

 treated with Norit and filtered, it is no longer suitable for growth, 

 but may be reactivated by the simple addition of peptone. 



' Numbers refer to the standard turbidity scale composed of varying suspen- 

 sions of BaSO<. 



