126 



SAOTEBIOLOGY. 



asbestos boards or thick felt, to prevent radiation of 

 heat and consequent fluctuations in temperature. In 

 the top of the chamber is a small opening through which 

 a thermometer projects into its interior. At either cor- 

 ner, leading into the space containing the water, are 



Fig. 30. 



Incubator used in bacteriological work. 



other openings for the reception of anotlicr thermometer 

 and a therm o-regulator, and for refilling the apparatus 

 as the water evaporates. On the side is a water-gauge 



