XIII. INCUBATORS. 



AN incubator (Fig. 113) consists essentially of a cham- 

 ber for the reception of cultivations, etc., surrounded by 

 a water jacket, the walls of which are of metal, usually 

 copper, and outside all an asbestos or felt jacket, or 



FIG. 113. Incubator- 



wooden casing. The water in the jacket is heated 

 by gas or electricity and maintained at some constant 

 temperature by a thermo-regulator. The cellular 

 incubator (Fig. 114) which was made for me 1 some 

 years ago is of the greatest practical utility. Here the 



1 Made by the firm of Chas. Hearson & Co., 235 Regent St., London, W. 



2l6 



