NUTRIENT BOUILLON 17 



A 15% solution of salt raises the boiling-point 2 1/2 C.; a 20%, 3 1/2 C., 

 and a 25%, 4 1/2 C. The raising of the boiling-point by calcium chloride is about 

 the same for similar strength solutions. 



Although the Bacteriological Committee of the A P. H. Association recom- 

 mends special steps to be taken in the preparation of gelatin and agar, yet for clinical 

 purposes it will be found satisfactory to keep on hand a stock of bouillon, and when 

 it is desired to make agar or gelatin to simply prepare such media from the stock 

 bouillon in the way to be subsequently given. 



NUTRIENT BOUILLON. 



This may be made either from fresh meat or from meat extract. 

 Media from fresh meat are usually lighter in color and possibly clearer. 

 In the Philippines, however, certain measures employed for the preser- 

 vation of the meat made it very difficult to prepare clear bouillon from 

 it, so that meat extract was used entirely. There is very little differ- 

 ence, if any, in the nutritive power of media made in either way. The 

 chief objections to fresh meat as a base are: i. It takes more time and 

 trouble. 2. The reaction, due to sarcolactic acid and acid salts, is 

 quite acid, so that it is necessary to titrate and neutralize the excess of 

 acidity. 3. The reaction of the finished media tends to change unless 

 the boiling at the time of making was very prolonged. 4. It is not 

 infrequent to have a heavy precipitate of phosphates thrown down at 

 the time of sterilization, thus making it necessary to repeat the process 

 of filtration and sterilization. 



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 for a 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 cot- 

 ton the scum of fat; then squeeze out the infusion with a strong muslin cloth, mak- 

 ing the amount up to 1000 c.c. This meat infusion contains all the albuminous mate- 

 rial 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 furthermore, when bouillon is used for blood cultures, 

 disintegration 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 gradually add the remaining 

 infusion until solution is complete. It is sometimes recommended to use a temper- 



