15 



allowing finely chopped lean meat mixed with twice its quan- 

 tity of water (2 c.c. of water for each, gram of meat) to 

 stand in a cool place for from 12 to 18 hours, or, the mix- 

 ture of meat and water may be heated with frequent stirring 

 at a temperature of 65" C. for a short time (one hour). 

 Each method has its peculiar advantages. When the meat 

 is macerated at a low temperature the muscle sugar is fre- 

 quently lost. When it is made by heating the meat the 

 bouillon usually contains a trace of muscle sugar. When 

 meat extract is used in place of the meat infusion the bouil- 

 lon 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 ex- 

 tract) and the method of preparing it to suit the conditions 

 in hand. It is sometimes desirable in bacteriological investi- 

 gations to resort to all of these methods. For the routine 

 work in the laboratory, bouillon prepared directly from the 

 meat by macerating it at a high temperature (65" C.) is 

 very satisfactory. 



Bouillon is used as the nutritive base in preparing agar 

 and gelatin. On this account the large quantities are stored 

 in flasks. (For other methods see text-books. Also Jour- 

 nal of the American Public Health Asso., Jan. 1898, p. 77.) 



§ 10. General Directions. Make 1000 c. c. of bouillon 

 and distribute it as follows : 



Put 7 c. c. in each of 10 small sterile test tubes. 



Put 300 c. c. in each of 2 flasks and the balance in a small 

 flask. 



Put 7 c. c. of distilled water in each of 5 small sterile test 

 tubes and sterilize them with the bouillon. These tubes 

 should be steamed or boiled for 10 minutes on each of the 

 two succeeding days. (They are to be used subsequently 

 in place of bouillon in making dilutions). Label the tubes, 

 "Sterile distilled water." 



Note. All media, in addition to that made by the student. 



