622 LABORATORY HINTS 



Glucose and Lactose Broth. 



To each loo c.c. of above i to 2 grm. of line g"lucose or lactose. 

 This is used for anaerobic bacteria. 



Nutrient Gelatin. 



To one litre of acid beef broth add 100 grm. of gelatin, 10 grm. of 

 peptone, and 5 grm. of salt. Place in water bath until solution is 

 clear, make faintly alkaline with NajOH, cool to 50° C, add the white 

 of an egg, after stirring steam for an hour, filter, and run into test- 

 tubes. Sterilize for fifteen minutes on three successive days. 



Agar-agar. 



15 grm. of powdered agar-agar well boiled with one litre of nutrient 

 broth for two hours until dissolved, replace the water .lost, see that it 



Hot-air sterilizer. 



is faintly alkaline, clear with egg-albumen, filter through a " Chardin " 

 filter paper. It remains solid at 40° C, and only melts completely 

 at 90° C. 



Glucose and Lactose Peptone Waters. 



10 grm. of peptone and 5 grm of salt dissolved in 1,000 c.c. of dis- 

 tilled water, boil well, neutralize in the usual way, boil and filter, run 

 into tubes and sterilize thrice. 



Add I to 2 per cent, of glucose or lactose to this, tinge it with 

 litmus solution to indicate production of acid and alkaline. 



It is a useful media for determining the fermentative power of 

 organisms. This medium is best placed in Durham's miniature test- 



