42 METHODS OF CULTIVATION OF BACTERIA. 



of a large filter funnel, and strain the fluid through it into 

 a flask. Pour the minced meat into the cloth, and gather- 

 ing up the edges of the cloth in the left hand, squeeze out 

 the juice still held back in the contained meat. Finish 

 this expression by putting the cloth and 

 its contents into a meat press (Fig. 6), 

 similar to that used by pharmacists in 

 preparing extracts ; thus squeeze out 

 the last drops. The resulting sanguine- 

 ous fluid contains the soluble albumins 

 of the meat, the soluble salts, extractives, 

 and colouring matter, chiefly hsemo- 

 globin. It is now boiled thoroughly 

 for two hours, by which process the 

 albumins coagulable by heat are coagu- 

 lated. Strain now through a clean 

 cloth, boil for another half- hour, and 

 filter through white Swedish filter paper 

 (best C. Schleicher u. Schull, No. 595). Make up 

 to 1000 c.c. with distilled water. The resulting fluid 

 ought to be quite transparent, of a yellowish colour 

 without any red tint. If there is any redness, the fluid 

 must be reboiled and filtered till this colour disappears, 

 otherwise in the later stages it will become opalescent. A 

 large quantity of the extract may be made at a time, and 

 what is not immediately required is put into a large flask, 

 the neck plugged with cotton wool, and the whole sterilised 

 by methods B (2) or (3). This extract contains very little 

 albuminous matter, and consists chiefly of the soluble salts of 

 the muscle, certain extractives, and altered colouring matters, 

 along with any slight traces of soluble proteid not coagulated 

 by heat. It is of acid reaction. We have now to see how, 

 by the addition of proteid and other matter, it may be 

 transformed into proper culture media. 



i. Bouillon Media. These consist of meat extract with 

 the addition of certain substances to render them suitable 

 for the growth of bacteria. 



i (a). Peptone Broth or Bouillon. Add to the meat 



