46 METHODS OF CULTIVATION OF BACTERIA 



by aseptic methods. The mixture is then allowed to solidify in the 

 sloped position. This medium is also very suitable for the growth of the 

 gonoeooous, meningococcus, and influenza bacillus. 



Blood-Alkali Agar (Dieudonn£). — This medium, introduced for the 

 culture of the cholera spirillum, for which purpose it has been found 

 extremely suitable, has the property of inhibiting the growth of most of 

 the intestinal bacteria ; for example, the b. coli does not grow on it, or 

 does so very slightly. A blood-alkali solution is prepared by adding 

 equal parts of defibrinated ox blood and of normal caustic soda solution ; 

 the solution may then be sterilised in the steam steriliser. Of this 

 solution three parts are added to seven parts of ordinary peptone-agar 

 rendered neutral to litmus, and the mixture is disposed in test-tubes. 



Novy and MacNeal's Medium for Culture of Trypanosomes. — 125 

 grammes rabbit or ox flesh are treated with 1000 c.c. distilled water, 

 as in making ordinary bouillon, and there are added to the meat 

 extract 20 grms. "Witte's peptone, 5 grms. sodium chloride, 20 grms. 

 agar, and 10 c.c. normal sodium carbonate. The medium is placed in 

 tubes and sterilised in the autoclave at 110° 0. for thirty minutes. It is 

 cooled at 50° C, and there is added to the medium in each tube twice 

 its volume of defibrinated rabbit blood, which has been prepared with 

 all aseptic precautions ; the tubes are allowed to set in the inclined 

 position. In inoculating such tubes they are placed in an upright 

 position for a few minutes, and then the infective material is introduced. 



Hiss's Serum Water Media.— These are composed of one part of ox's 

 serum and three parts of distilled water with 1 per cent, litmus ; various 

 sugars in a, pure condition are added in the proportion of 1 per cent, 

 (see p. 78). The development of acid by fermentation is shown by the 

 alteration of the colour and by coagulation of the medium. These media 

 do not coagulate at 100° 0., and thus can be sterilised in the steam 

 steriliser. They have been extensively used by American workers in 

 studying the fermentative properties of the b. dysenteriae, b. coli, etc. 



Egg Media. 



Within recent years media containing either the yolk, or both 

 the yolk and the white of egg, have been used for the culture 

 of the tubercle bacillus by Dorset and others. The following 

 will be found very suitable : — 



Dorset's Egg Medium. — The contents of four fresh eggs are 

 well beaten up, 25 c.c. of water are added and thoroughly 

 mixed, the mixture being passed through muslin to remove 

 air bells. The fluid is then filled into tubes, and these 

 are heated for four hours in the sloped position at 70° C. 

 Another method of solidifying the medium is to place the tubes 

 high up in a Koch's steriliser for 3-5 minutes. In either case the 

 medium may then be covered with -8 per cent, sodium chloride 

 solution and (sterilised in the autoclave (p. 29). Before the 

 inoculation of a tube, two drops of sterilised water are placed 

 on the surface. The inoculation material is well rubbed over 

 the surface of [the medium, the tubes are sealed with a few 



