38 



APPLIED BACTERIOLOGY 



tion ' temperature is meant one about the heat of the 

 human body, i.e., 37° C. ( = 98-6° P.). 



The incubator, or warm chamber, consists essentially of 

 an inner chamber of copper, fitted with a door; this 

 chamber is surrounded with an outer casing, which is 

 protected by one or more layers of felt, or some other 



Fia. 6. — Incubator, 



non-conducting material. The space between the two 

 walls is filled with water, which is warmed to the necessary 

 extent by means of a small gas-burner. To secure an even 

 and regular temperature, the water or air in the inner 

 chamber is controlled by means of a thermostat or 

 regulator, generally a mercurial one of the Page or Eeichert 



