SCIENTIFIC PROCEEDINGS. 



Abstracts of Communications. 

 One hundred sixteenth meeting. 



Columbia University, May 20, IQ21. 

 President Wallace in the chair. 



134 (17x6) 



Variations in the streptolysin curve in serum media. 



By FRANKLIN A. STEVENS and CLIFFORD L. LAMAR. 



[From the Medical Clinic of the Presbyterian Hospital, 

 Columbia University, New York City.] 



In the growth of hemolytic streptococci in serum media, the 

 hemolysin, titrated from hour to hour, shows a gradual ascending 

 curve of concentration which reaches a maximum at about the 

 sixth to the twelfth hour of growth, and then falls rapidly. This 

 curve may be modified by the character of the culture used to seed 

 the media, by the quantity of serum present, the source of the sera, 

 and the amount of peptone in the broth. There are two variations 

 which occur; variations in concentration of hemolysin, and in the 

 time that hemolysin first appears in the culture and later the time 

 at which the maximum amount can be demonstrated. With 

 similar seeding, and only one variant introduced in experiments, 

 these variations are brought out very sharply. Cultures in 20 

 per cent, rabbit serum and horse serum in broth without peptone 

 show that rabbit serum media allows the production of the lysin 

 sooner and does not give as great concentrations as horse serum. 

 The lower percentages of these sera, when seeded with different 

 plain broth cultures give greater variations in the maximum 

 titre, but these variations are largely obviated in 20 per cent. 



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