122 APPENDIX. 



N 

 hydroxid or — hydrochloric acid. As a rule, the reaction 



will be acid and the alkali may be used. The determina- 

 tion should be made not less than three times, and the 

 average of the results taken. 



LACTOSE AGAR. 



This medium is made in the same manner as nutrient 

 agar except that 2 per cent of lactose is added after the 

 final nitration and the reaction is adjusted to — .5. 



GLYCERINE AGAR. 



For this medium, 5 per cent glycerine is added to nutri- 

 ent agar immediately after final filtration. 



SUGAR BROTH. 



The most important and widely used sugar broth is 

 that containing dextrose, although lactose and saccharose 

 and occasionally maltose are used for special experi- 

 mental work. 



Dextrose broth may be easily prepared by adding 

 2 per cent of dextrose to ordinary broth just before the 

 final filtration, and making the reaction neutral. For 

 the preparation of lactose, saccharose, or maltose broth, 

 however, where it is necessary to eliminate dextrose, the 

 meat infusion after filtration is placed in an Erlenmeyer 

 flask, inoculated with an active broth culture of B. coli 



