AGAR-AGAR MEDIA 53 



which is placed obliquely in the flask, and a small Bunsen flame fixed at 

 an angle a short distance from the neck of the glass funnel. The 

 gelatine Jilt ers easily by this method, and a hot water funnel is un- 

 necessary.) 



6. The reaction is again tested, and if still faintly alkaline, fill into 

 tubes, about 10 c.c. in each, and close with cotton wadding plugs. 

 ( ; The Koch method of sterilizing wadding and tubes before use is now 

 dispensed with, except for blood serum media.'') 



7. Sterilize the tubes of gelatine in the steam sterilizer for fifteen 

 minutes on each of three successive days. The gelatine must finally 

 be as clear as glass. 



XC. GRAPE SUGAR GELATINE. 



To 100 c.c. of nutrient gelatine, before it is sterilized (see 89, 

 No. 6), add 2 grammes of grape sugar. 



XCI. MILK SUGAR GELATINE. 



Add 2 grammes of milk sugar to 100 c.c. of gelatine in the manner 

 described for grape sugar gelatine. 



XCII. THREE PER CENT. COMMON SALT GELATINE. 



Add 3 per cent, instead of the J per cent, of common salt used in 

 the ordinary process of making nutrient gelatine. 



AGAR-AGAR MEDIA. 



XCIII. ORDINARY AGAR-AGAR. 



1. Make 1 litre of meat infusion (see Bouillon, processes Nos. 1 

 and 2, 73), add 



1 per cent, of peptone siccum . . 10 grammes. 



J common salt . . 5 



2. Place the above in a clean flask, heat in a water-bath one to 

 one and a half hours, and add 1 to 2 per cent. (1J is the amount 

 generally used) of agar-agar, finely powdered or cut into very small 

 pieces, and boil five to eight hours until the agar-agar is thoroughly 

 dissolved. 



3. Make alkaline with sodium bicarbonate solution. 



