THE BACTERIOLOGICAL LABORATORY 39 



chamber, covered on five sides with felt, but in 

 front the felt forms a loose flap, which can be raised. 

 The interspace between the two walls is filled with 

 water, which is heated from below. The incubator 

 has two glass doors, a moveable shelf, a water-gauge, 

 and a gas-regulator. 



Among other good incubators are those of Pas- 

 teur, 1 Eohrbeck, 1 Klein, 2 Gautier, Abel, D'Arsonval. 

 and Hueppe. Whatever form of in- 

 cubator is preferred, it is essential 

 that it should be provided with a 

 gas or heat regulator. The acting 

 agent in most regulators of this de- 

 scription is either a membrane, 

 mercury, or electricity. Tieftrunk's, 

 Giroud's, and Elster's are membrane 

 gas -regulators ; Eeichert's, Page's, 

 Schiitz's, Fraenkel's, and Meyer's 

 are mercury heat - regulators ; and 

 Schlosing's is a membrane heat-regu- 

 lator. Fig. 15 represents Keichert's 

 mercury heat - regulator. It is a Flo> 15> 

 tube with two lateral arms (a and REICHERT-S 



, x ,, .. f , \ , . REGULATOR. 



0); the upper portion of which is 

 extended into a funnel-like arrangement, bearing 

 the arm b. Into this funnel-like opening fits a 

 hollow T piece. ' One arm of the T piece is open, 

 and connected with the gas supply; the vertical 



1 For figures of these incubators see Dr. Griffiths' Researches 

 on Micro-Organisms, pp. 19 and 20. 



2 See Dr. Klein's Micro- Organisms and Disease (3d ed.), 

 p. 15. 



