8. PREPAEATION OP NUTRIENT MEDIA. 



A. BOUILLON. 



1. Add one pound of finely-chopped lean meat to 1000 

 cc of water, and allow this to stand from twelve to twen- 

 ty-four hours in a cool place. 



2. Strain through cheese-cloth, or a coarse towel, and 

 squeeze in a meat-press, or by twisting the ends of the 

 cloth, until 1000 cc of so-called "meat-" or "flesh-water," 

 are obtained. If less than 1,000 cc are thus obtained, 

 make up the deficiency with fresh water. 



3. Add 5g. common salt and dissolve. 



4. Add lOg. dried peptone and dissolve. 



6. Boil one-quarter hour, either in steam or over an 

 open flame. 



6. Make the solution slightly alkaline by the addi- 

 tion of sodium carbonate (saturated solution). 



7. Boil from three-quarters to one hour, filter; the 

 filtrate should be clear, if not, add the whites of two eggs, 

 mix rapidly, boil from a quarter to half hour and again 

 filter.* 



B. BOUILLON (PETEI AND MAASZEN METHOD). 



1. Mix meat and water, as above, under A 1, and let 

 it stand for one hour. 



2. Heat in water-bath to about 60 degrees C. for three 

 hours. 



3. Boil one-half hour. 



4. FUter and when cool make slightly alkaline. 



5. Add 5g. salt and dissolve. 



6. Add lOg. dried Peptone and dissolve. 



7. Boil one-quarter hour (best over a free flame). 



8. Add glycerine if desired. 



9. Filter. 



iTn the preparation of nil the nentonijed media, it is often the case 

 that the final filtration is not snfEeiently clenr. This cloiidinesg is gen- 

 erally due to the fine particles of matter suspended in the fluid. Tf esg 

 albumen is now added, and the solution is afr.iin hoiled, these particles 

 are generally cauRht in the coaffulum. and they can he removed with 

 the filter. It is. perhaps, a good practice always to add the eggs he- 

 fore the last boiling, thus ayoiding a second filtration. Even after every 

 precaution has been taken, it sometimes seems impossible to obtain n 

 perfectly clear filtrate; in such cases, the repeated addition of eggs 

 and' boiling are recommended; in the case of bouillon, the narticlea 

 will sink to the bottom on cooling, and, as a rule, may then be 'fil- 

 tered off. 



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