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PREPARATION OF NUTRIENT BOUILLON 

 AND OF NUTRIENT AGAR. 



Place 500 g. of chopped lean beef into a clean 1^ or 

 2-litre flask ; add 1000 c. c. of tap-water and insert a cotton 

 plug into the neck of the flask. Shake the flask repeatedly 

 during the next 15 or 30 minutes, then immerse in a water- 

 bath containing boiling water, and heat for 15 or 30 min- 

 utes. Filter through muslin, and to the filtrate or meat 

 extract thus obtained add 



10 g. of dry peptone, 

 5 g. of common salt. 



Warm in the water-bath for some minutes, then render 

 slightly alkaline by cautious addition of saturated sodium 

 carbonate solution. Continue heating in a water-bath, 

 with occasional shaking, for f to 1 hour, then filter through 

 a plaited filter bouillon. The bouillon thus prepared 

 should be (1) perfectly clear; (2) should be slightly 

 alkaline in reaction, and (3) should not coagulate or cloud 

 on heating. 



Take 100 c. c. of the bouillon and fill into sterilized 

 plugged test-tubes, using a small funnel, to a depth of 

 1 1^ \i\c\\e'&= ordinary bouillon. 



To 100 c. c. of the bouillon add two per cent, of 

 glucose, warm till dissolved, then fill likewise into test- 

 lubes glucose bouillon. 



To the remainder of the bouillon (800 c. c.) add H to 2 

 per cent, of agar, previously cut up into very small pieces. 

 Place on a wire gauze and heat at just below the boiling 

 point (to prevent frothing) for2or3hours, till the agar has 

 completely dissolved. Then turn the flame low and con- 

 tinue heating for 1 or 2 hours, when the suspended matter 

 largely subsides to the bottom. Then filter by decaritation 

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