NUTRIENT MEDIA AND METHODS OF CULTIVATION. 119 



of neutralisation with carbonate of soda solution, the flask of broth 

 is placed in\ the steam steriliser for half an hour at 100 C. A 

 clear liquid results on nitration which is transferred to plugged 

 sterilised flasks or test-tubes, and sterilisation effected by exposing 

 the*n in the steam steriliser for half an hour at 100 C. for two 



FIG. 47. APPARATUS FOE STERILISATION BY STEAM UNDER PRESSURE. 



or three successive days, or] by; I using the apparatus for sterilising 

 by steam under pressure. For some bacteria a more suitable 

 cultivating medium is obtained by the addition of glycerine or 

 grape-sugar. 



Liquid Blood Serum. The preparation of blood serum has 

 already been described. ' It may be required for cultivations before 

 the final treatment by which it is solidified, for example, in the 

 method of drop-cultivation, and may be used with the addition of 

 glycerine or grape-sugar. Hydrocele fluid, peritonitic arid pleuritic 



