PREPARATION OF NUTRIENT MEDIA. 8 1 



of bread and allowing it to dry in the oven. It 

 is then broken up, and reduced to a fine powder 

 with a pestle and mortar. Small, carefully cleansed, 

 conical, or globe-shaped flasks are plugged with 

 cotton wool and sterilised in the oven. When 

 cool a small quantity of the powder is placed in 

 them, and sterilised water added in the proportion 

 of one part for every four of the powder. The 

 paste is sterilised by steaming in the steriliser 

 at 100 C. for half an hour for three successive 

 days. The flasks can be reversed, and are inocu- 

 lated in the usual way with a platinum needle. 



CULTIVATIONS ON VEGETABLES, FRUIT, WHITE OF 

 EGG, ETC. 



Boiled carrots and other vegetables, and various 

 kinds of stewed fruit, are also occasionally em- 

 ployed for the cultivation of bacteria. The sterili- 

 sation of these media must be carried out on the 

 principles already explained. White of egg may 

 be poured out on sterilised glass plates, or in 

 shallow glass dishes, boiled in the steam-steriliser 

 and after inoculation, placed in a damp chamber. 



(D) PREPARATION AND EMPLOYMENT OF STERILE 

 BLOOD SERUM. 



The tubercle-bacillus, the bacillus of glanders, and 

 a few other micro-organisms, thrive best when culti- 



6 



