CHAPTER III 



PREPARATION OF CULTURE MEDIA 

 Each student is required to make up the following 

 amounts of culture media: 



EXERCISE I. PREPARATION OF NUTRIENT AGAR-AGAR 



1. Weigh the saucepan without the lid accurately 

 and make note of the weight. 



2. Measure into the saucepan 1000 c.c. of tap- water, 

 adding about 300 c.c. of water to allow for evaporation, 

 and heat over gas. 



3. Cut and shred i<;g. of agar-agar (ij per cent.), 

 add to the water, and boil slowly, with constant stirring, 

 until perfectly dissolved, taking care not to overheat. 



4. Add 3 g. of extract of beef. When dissolved, 

 remove the saucepan from the flame, and 



5. Slowly dust 10 ( i per cent.) g. of Witte's peptone 

 on the surface, constantly stirring until perfectly dissolved. 

 Avoid allowing the peptone to clump. 



NOTE. Agar-agar (called simply "agar") is a watery ex- 

 tract of certain seaweeds found on the Pacific coast of Asia. 



