182 



EXPERIMENTAL PHARMACOLOGY 



fairly rapid movements up and down correspond to the 

 regular respiratory movements of the animal. But in ad- 

 dition to these rapid movements a larger and more pro- 



Breathinq pan 



Inner pan 

 Trouqh (wafer) 

 Outer pan 



Respiratory 

 openinq 

 NaOH solution 



Hinge rod 

 Oxyqen inlet 

 Ether inlet 



Fig. 173. Inner construction of the pans shown in Fig. 172. These pans can be 

 made of sheet brass or tinned iron. Pans which can be used for the purpose can often 

 be purchased at a hardware store (or a ten cent store). (See Journal of Laboratory and 

 Clinical Medicine, 1916, ii, p. 145; also ibid, 1916, ii, p. 94. ) 



Removable 

 hinge rod 



Counrerbalancinq 

 weiqhf- 



Stopper 



Ji Inches 



13 xiz 



r. T. rtillrck 



Fig. 174. Lateral view of a cross-section of the apparatus shown in Fig. 172. The 

 breathing pan is best made of very thin sheet brass (which is easily soldered and is not 

 affected by alkalies as is aluminum). The pan should be carefully counterpoised with 

 an adjustable weight. The dimensions are indicated in inches on the scale. 



longed movement of the disc occurs. This corresponds to 

 the injection of oxygen from the tank into the pan when 

 the disc will be lifted up a considerable distance (perhaps 



