THE NATURE OF HEMOLYSINS 



91 



Figure 1 is typical of a number of curves derived when two 

 different kinds of media were used, each having an original pH 

 of 7.2, one being the standard medium, the other the standard 

 plus 0.2 per cent glucose. All tubes were heated to 37°C. before 





Fig. 1. Solid Line, Plain Broth Standard Medium 

 Broken Line, Glucose Broth Standard Medium 



inoculating, and then inoculated with a 4 mm. loopful from a 

 twelve hour 10 per cent serum-broth culture of Streptococcus 

 hemolyticus. The tubes were incubated at 37°C. and every two 

 hours one tube of each kind of medium was removed, a part 

 being centrifugated for one-half hour at 1800 revolutions per 

 minute, and the pH of the remaining portion determined. Then 

 0.1 cc. of the supernatant fluid was added to 1 cc. of cell suspen- 

 sion and placed in a water bath at 37°C. for one hour. The 

 abscissae of the chart represent minutes required for complete 

 hemolysis, the ordinates showing the age of the culture. 



