HISTOLOGICAL METHODS. 



145 



marble in another bottle Q When the gas is desired, A 

 is elevated upon some support. The gas is passed 

 through a wash bottle (C) containing water, and 

 thence to a T tube (D). The microscopic gas 

 chamber is joined to the tube E ; and when the 

 transmission of gas through it is desired, a clamp 

 (G) is placed upon the waste-tube F. When it is 



FIG. 46. Carbonic acid apparatus. 



necessary to rapidly arrest the transmission of the 

 gas, a clamp is placed on H. The gas accumu- 

 lates in B, and drives the acid back into A. A 

 stream of air may be pumped through the gas 

 cell by connecting an elastic pump to F, and 

 placing the clamp G upon H. pf IG t te 45 'for 



259. Application of Heat. Simple hot 

 stage. A stage suitable for roughly heating a 

 microscopic object may be made of a plate of tin 

 9 x 2j inches, with an aperture about a quarter 

 of an inch in diameter in the centre (Fig. 47). The plate 

 should be long enough to project some inches on each 

 side of the stage of the microscope. The slide, with the 

 object to be heated, is laid on the plate, the object is focal- 

 ised, and a spirit lamp is applied to one end of the plate. 

 It is convenient to apply the lamp to the right extremity, 

 and to keep the forefinger of the left hand on the plate 



removing 

 fluid from 

 microsco- 

 pic ob- 

 jects. 



