INCUBATION OF CULTURE MEDIA. 



"5 



sealed. In this way separate cultures of isolated organisms are ob- 

 tained, and their characteristics may be observed with great ease in 

 this form of cultivation. 



Incubation. 



65. Incubation of culture media which have been inoculated should 

 be, as far as possible, carried on at even temperatures. To maintain 

 any temperature equally for a length of time, one or other form of care- 

 fully constructed incubator is absolutely necessary. That depicted in 

 Fig. 60 is a convenient form, from its having double glass sides, 



Fig. 60. — Incubator, with regulator (a) in air chamber. 



which allow of the contents being from time to time examined, without 

 removing them from the wanner atmosphere within the apparatus. The 

 apparatus is double-walled, and the interspace between the walls is 

 occupied by a layer of water. There is, of course, a layer of air be- 

 tween the double glass walls. The heating is carried on by a small 

 Bunsen burner in connection with a gas regulator, which controls 

 the amount of gas supplied to it. The tube of the regulator lies in 

 the water, within the hollow walls of the incubator, or in the air 

 chamber, and is so constructed that when the temperature of the 



