184 ATLAS OF BACTERIOLOGY. 



15. Loffler's serum mixture for diphtheria bacilli. 

 Three parts of beef or sheep serum are mixed with 

 one part calf's bouillon, which contains one per cent 

 grape sugar, one per cent peptone, and one-half per 

 cent sodium chloride. 



16. Entirely different from the other media is that 

 first devised by Kulme, modified by various writers, 

 and finally made somewhat more practicable by 

 Stutzer and Burri. We refer to the silicic acid nu- 

 trient medium. Gelatinous silicic acid, whioh is 

 merely mixed with a few salts, is an important nu- 

 trient medium for certain organisms (for example, the 

 nitrate-producers) on account of the lack of organic 

 nutrient substances. For the somewhat complicated 

 manipulation, vide Stutzer and Burri (C. B., Yol. I., 

 PartY., 722). 



2. THE EMPLOYMENT OF THE DIFFERENT NUTRIENT 

 MEDIA DEPENDS UPON THE FOLLOWING VIEW- 

 POINTS : 



I. Fluids (bouillon, sugar bouillon, milk, non- 

 albuminous nutrient solution). 



1. To produce cultures en masse. 



2. To obtain bacterial solutions containing an ac- 

 curately determinable number of bacteria (counting 

 by means of plates). 



3. To observe the development of membrane and 

 sediment. 



4. To study the metabolic products. 

 II. Solid Nutrient Media. 



1. Gelatinous nutrient media. The most exten- 

 sive use is made of gelatinous, transparent nutrient 



