Cultivation of Micro-organisms 225 



All accurate bacteriologic culture experiments require 

 that an exact knowledge of the chemistry of the media used 

 shall be at hand. The importance of this and the necessity 

 for having exact information regarding the reaction of the 

 media are well brought out in the following excerpts from 



Fig. 44. Buret for titrating media. (From Hiss and Zinsser, "Text- 

 Book of Bacteriology," D. Appleton & Co,, Publishers.) 



the Report of the Committee of Bacteriologists of the Amer- 

 ican Public Health Association :* 



"The first thing to obtain is a standard 'indicator' which will give 

 uniform results. These requirements are best fulfilled by phenol- 

 phthalein." 



" The question of the proper reaction of media for the cultivation 

 of bacteria and the method of obtaining this reaction have been dis- 

 cussed in a valuable paper by Mr. George W. Fuller, published in the 



* "Jour. Amer. Public Health Assoc.," Jan., 1898, p. 72. 

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