THE PREPARATION OF BOUILLON 7 



EXERCISE III 



THE PREPARATION OF BOUILLON 



10. Bouillon is the liquid medium most commonly employed 

 in cultivating bacteria. It is practically a beef tea containing 

 peptone. There are several methods recommended for mak- 

 ing it. It may be made directly from simple meat infusion 

 or it may be made from meat extract. The meat infusion 

 is prepared either by allowing finely chopped lean meat mixed 

 with twice its quantity of distilled or filtered and boiled tap 

 water (2 cc. of water for each gram of meat) to stand in a 

 cool place for from 12 to 18 hours, or the mixture of meat 

 and water may be heated with frequent stirring at a tempera- 

 ture of 65° C. for a short time (one hour). Each has its 

 advantages. When meat extract is used in place of the meat 

 infusion, the bouillon does not seem to be a favorable culture 

 fluid for certain bacteria. In making bouillon, therefore, it 

 becomes necessary to determine the kind (whether from meat 

 infusion or extract) and the method of preparing it to suit the 

 conditions in hand. It is sometimes desirable in bacteriologic 

 investigations to resort to all of these methods. For routine 

 work in the laboratory, bouillon prepared directly from the 

 meat by macerating it for a short time at a high temperature 

 (60° to 65" C.) is very satisfactory. The addition of peptone 

 and the neutralization of the liquid are the same in both cases. 



Bouillon is used as the nutritive base in preparing agar and 

 gelatin. On this account large quantities are stored in flasks. 

 (For other methods see text-books. Also Report (Journal) of 

 the Am. Public Health Asso., January, 1898, p. 77.) 



Referen'CES. Chapters on making culture media in text- 

 books. Jour, of the Am. Public Health Asso., October, 1895, and 

 January, 1898, p. 77. Smith, The Jour, of Exper. Med., Vol. Ill 

 (1898), p. 647- 



