APPENDIX 



PREPARATION OF CULTURE MEDIA 



In view of the marked influence upon bacteriological 

 reactions of variations in culture media caused by differ- 

 ences both in ingredients and in technique of preparation, 

 it is necessary that uniform methods be used in order to 

 obtain comparable data. In spedf}dng the various ingre- 

 dients used in culture media it is the intention that they 

 shall be uniform in quaUty, but it is not the intention 

 that the recommendations as to ingredients and technical 

 manipulations shall stand in the way of true progress as 

 to improvements. When, however, improved or modified 

 methods are used, the variations from the standard methods 

 shall be plainly set forth together with the reasons for the 

 modifications. 



INGREDIENTS 



Distilled water sliall be used in the preparation of stand-: 

 ard cvilture media. 



Infusions of fresh lean meat, and not meat extract, 

 shall be used as the basis of various media. 



Peptone shall be that of Witte (dry from meat). 



Gelatin shall be the best French brand, so called. It 

 shall be as free as possible from acids and other impurities, 

 and shall be of such a character that a lo per cent solution 



* From the Report of the Committee on Standard Methods of the 

 American Public Health Association. 



265 



