To Prepare Bouillon from Meat Extract 



193 



n. To Prepare Bouillon from Meat Extract. — When desirable, the 

 bouillon may also be prepared from beef-extract, the method being 

 very simple: To 1000 cc. of clean water 10 grams of beef-peptone, 

 5 grams of sodium chlorid, and about 2 grams of beef-extract are 

 added. The solution is boiled until the constituents are dissolved, 

 titrated, and filtered when cold. If it be filtered while hot, there is 

 always a subsequent precipitation of pieat-salts, which clouds it. 



Bouillon and other liquid culture media are best dispensed and 

 ■ kept in small receptacles — test-tubes or flasks — ^in order that a single 

 contaminating organism, should it enter, may not spoil the entire 



Kg- 37. — Funnel for filling tubes with culture media (Warren): a, Funnel 

 containing the culture media in liquid condition; b, pinch-cock by which the floiy 

 of fluid into the test-tube is regulated; c, rubber tubing. 



quantity. A convenient, simple apparatus for filling tubes with 

 liquid media consists of a funnel to which a short glass pipet is at- 

 tached by a bit of rubber tubing. A pinch-cock controls the outflow 

 of the liquid. The apparatus need not be steriHzed before using, as 

 the culture medium must subsequently be sterilized either by the 

 intermittent method or in the autoclave after the tubes are filled. 

 The test-tubes and flasks into which the culture medium is filled 

 must, however, be previously plugged and sterilized by dry heat, 

 unless the subsequent sterilization is to be performed in the auto- 

 clave, when it may be unnecessary. 

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