1 6 CULTURE MEDIA. 



If fresh meat is used, take about 500 grams (one pound), remove 

 fat and cut it up with a sausage mill or purchase the meat already 

 cut up as fora Hamburg steak. It makes little difference whether the 

 amount be 100 grams more or less. Place the chopped-up meat in a 

 receptacle and pour 1000 c.c. of water over it. Keep in the ice chest 

 over night and the next morning skim off with a piece of absorbent 

 cotton the scum of fat; then squeeze out the infusion with a strong 

 muslin cloth, making the amount up to 1000 c.c. This meat 

 infusion contains all the albuminous material necessary for the 

 clarification of the bouillon. It is convenient to designate this 

 meat base as Meat Infusion to distinguish from the base containing 

 meat extract. 



Having obtained 1000 c.c. of this 50% meat infusion, we dissolve in 

 it i% of Witte's peptone and 1/2% of sodium chloride. While there is 

 a sufficiency of the various salts necessary for bacterial development 

 in the meat juices, yet there is not enough to give the best results when 

 bouillon cultures of various organisms are used for agglutination tests; 

 and futhermore, when bouillon is used for blood cultures, disinte- 

 gration of the red cells, with clouding of the clear medium, may occur 

 if there be not sufficient salt present to prevent this. 



The salt and the peptone are best put in a mortar, and adding about 

 one ounce of the meat infusion we make a pasty mass; then we grad- 

 ually add the remaining infusion until solution is complete. It is 

 sometimes recommended to use a temperature of 50 C. to facilitate 

 the solution of the peptone. This is not necessary, and if the tempera- 

 tare is not watched closely it might go up to 65 C. or higher and we 

 should lose the clearing albuminous material from its coagulation. 

 Of this rather cloudy solution take up 10 c.c. with a pipette and let it 

 run out into a beaker. Add forty c.c. of distilled or rain water and 

 about six drops of a 0.5% phenolphthalein solution. (Phenolphtha- 

 lein, 0.5; dilute alcohol, 100 c.c.) Now from a burette filled with 

 decinormal sodium hydrate solution, run in this solution until we have 

 the development of a rich violet-pink color in the diluted bouillon in the 

 beaker. To obtain a standard for comparison, simply add six drops of 

 the phenolphthalein solution to 50 c.c. of water and add about i c.c. of 

 the N/io sodium hydrate solution. As soon as we have obtained a 



