46 



PHARMACEUTICAL BACTERIOLOGY. 



Mix ingredients in a rice cooker and boil for one-half hour, stirring fre- 

 quently; neutralize and filter. This forms a very efficient culture medium 

 for most bacteria, and is clear and remains solid at ordinary temperatures. 

 It must be borne in mind, however, that frequent or prolonged heating tends 

 to liquefy gelatin permanently. 



Fig. 22. — This is a copper double-walled incubator covered with non-conducting 

 material and provided with a water gauge, tubulations for thermometer and thermostat, 

 a ventilating strip, enclosed base and inner glass door. The incubating chamber is 24 cm. 

 high, 30 cm. wide and 24 cm. deep. 



I. Agar Medium. — Agar is a seaweed found on the Japanese coast. It 

 forms an important article of diet among the Japanese and Chinese. The 

 medium consists of 



Beef Extract, 



Agar, 



Salt, 



Peptone, 



Distilled Water, 



3 gm. 



15 gm. 



S gm. 



10 gm. 



1000 c.c. 



Prepare like the gelatin medium. Agar is difficult to filter, and the 

 medium is never quite clear. The agar medium liquefies at a higher tem- 

 perature than gelatin, and does not tend to remain liquid, no matter how 

 often or how long it may be heated. 



