STUDIES ON CULTURAL REQUIREMENTS OF 

 BACTERIA. II 



J. HOWARD MUELLER 



From the Department of Bacteriology, College of Physicians and Surgeons, 

 Columbia Vniversily, New York 



Received for publication November 1, 1921 



In the introductory paper (Mueller, 1922) of this series of 

 studies, it was intimated that by treating an infusion of beef 

 heart with charcoal, two factors necessary in the growth of 

 hemolytic streptococci were removed, and that these factors 

 could be again supplied by the addition to the charcoal treated 

 infusion of commercial peptone or of a sulphuric acid hydrolysate 

 of casein. The main facts learned up to this time about these 

 two growth determining substances have been already briefly 

 reported (Mueller, 1920), and will be here presented in detail. 

 Work upon these substances has not yet been completed in the 

 sense of chemical isolation and identification, and it is hoped 

 that after further investigation which is now under way, it will 

 be possible to give a more definite report of their nature. 



TECHNIC 



The general technic of preparation of media, adjustment of 

 reaction, inoculation and recording of results, together with the 

 method of carrying the test strain of streptococcus in culture, 

 etc., has been fully described in the introductory paper (Mueller, 

 1922), and need not be repeated here. 



Removal of certain growth determining factors from beef heart 

 infusion by charcoal, and reactivation of the charcoal treated infu- 

 sion by means of peptone 



Three hundred cubic centimeters of a beef heart infusion, 

 prepared by mixing chopped heart muscle and water in the pro- 



325 



