Appendix. 207 



than offset this advantage. Consequently, when possible, 

 media shall be put at once into tubes and placed in cold 

 storage. 



To guard against changes due to evaporation all media 

 not used promptly shall be stored in a moist atmosphere, 

 preferably in an ice-box, or else the flask shall be sealed 

 by dipping the cotton plug in paraffin. 



NUTRIENT BROTH. 



Nutrient broth shall be prepared as follows: Infuse 

 500 g. chopped lean meat 24 hours with 1000 c.c. dis- 

 tilled water, in refrigerator. Restore loss by evaporation. 

 Strain infusion through cotton flannel. Add one per cent 

 pepton. Warm on water bath, stirring until the pep- 

 ton is dissolved. Heat over boiling water (or steam) 

 bath 30 minutes. Restore loss by evaporation. Titrate. 

 Adjust reaction to + i per cent by adding normal hydro- 

 chloric acid or normal sodium hydrate, as required. Boil 

 two minutes over free flame, constantly stirring. Restore 

 loss by evaporation. Filter through absorbent cotton and 

 cotton flannel, passing the liquid through until clear. 

 Titrate and record final reaction. Tube, using 10 c.c. in 

 each tube. Sterilize. 



SUGAR BROTHS. 



Sugar broths shall be prepared in the same general 

 manner as the standard nutrient broth, with the addition 

 of one per cent of dextrose, lactose, saccharose or other 

 sugar; or the sugar may be added to the completed 



