CHAPTER III. 



CULTIVATION ON PLATES AND IN ESMARCh's TUBES. 



At first glass plates were employed for cultivations, 

 but now the cultivation dishes, of which a diagram 

 and a description may be found in the preceding 

 chapter, are used with great advantage in their stead. 

 These dishes are always sterilised before they are 

 used, by being left for two or three hours ia the hot- 

 air steriliser. 



By means of these cultures on plates or on dishes, 

 the different kinds of bacteria may be separated from 

 one another, and cultivated apart. Thus, for instance, 

 if we wish to isolate the different varieties which ap- 

 pear in meat infusion (Chap. I.), we proceed in the 

 following manner : — A test-tube, containing gelatine, 

 is heated to 40° C. in order to liquefy its contents, 

 which are then poured quickly into a sterilised cultiva- 

 tion dish, the lid of which is held with the left hand 

 over the test-tube, in order as much as possible to 

 prevent the bacteria which are present in the air from 

 falling into the tube. After the lid has been replaced 

 on the dish, a small quantity of the meat infusion is 



