57 



EXERCISE XXVI. 



PREPARATION OF CULTURE MEDIA. 



§ go. General directions. Prepare, after the methods 

 already given (Exercise III, IV and X) the following media : 



15 small test tubes of bouillon. 



ID small and 15 large test tubes of agar. 



10 small and 15 large test tubes of gelatin. 



5 small test tubes of glucose agar. 



5 small test tubes of milk. 



5 small test tubes of litmus milk. 



5 small or large test tubes of potato. 



5 small test tubes of distilled water. 



4 Fermentation tubes of glucose bouillon. 



4 Fermentation tubes of lactose bouillon. 



4 Fermentation tubes of saccharose bouillon. 



10 small test tubes of Dunham's solution. 



A tube of each of these media will constitute a "set of 

 media" as subsequently used for convenience in these direc- 

 tions. 



§91. Dunham's peptone solution. This is simply a 

 solution of peptone and sodium chloride in distilled water. 

 The formula is as follows : 



Dried peptone I gram. 



Sodium chloride 0.5 gram. 



Distilled water 100 c.c. 



Dissolve the peptone and salt in the water and distribute it 

 in the tubes (7 c.c. each) and sterilize the same as bouillon. 

 This is used for making the indol (cholera-red) test. A 

 sugar free bouillon has been found better but for an elemen- 

 tary course Dunham's solution is more desirable. See article 

 by T. Smith, Journal of Experimental Medicine, Vol. II 

 (1897)- P- 543- 



