88 MANUAL OF BACTERIOLOGY. 



walls, the space between the two being filled with water. 

 The outer surface is covered with some non-conductor of 

 heat, such as felt or asbestos. At one side is a door, which 



Tic. 22. 



Incubator. 



is also double. The inner door is of K"^ lss < the outer door 

 is of copper covered with asbestos. At one side is a gauge 

 which indicates the level at which the water stands in the 



