A MICROSCOPE-STAGE INCUBATOR. 



325 



incandescent to the egg-cell, but also increases the size of the 

 bulb, and thus increases the sensitivity of the regulator. 



For my purpose, the regulator is adjusted so as to maintain a 

 temperature of about 39. 4 C. in the neighborhood of the ther- 

 mometer t, which is placed as close to the egg-cell as will permit 

 an easy manipulation of the objectives. In order to keep the 

 temperature constant it is necessary to have a circulation of the 



Fig. 1. 



water within the incubator, and the way in which this is accom- 

 plished can be understood better from the drawing (Fig. 2), in 

 which the greater part of the top and back has been cut away 

 in order to show the internal structure. The shaded part of the 

 drawing represents that portion of the incubator that fits about 

 the microscope stage. For convenience we may speak of three 

 apartments, A, B, and C. A is separated from B and C by a 



