LIV.] 



SUSPENSION METHODS FOR HEART. 



267 



By this method, also, the effect of heat, cold, drugs on the heart 

 can be ascertained. 



N.B. If it is desired to ascertain the action of a drug on the 

 heart by this method, then make a snip in the heart so that the 

 blood may flow out and the drug act directly on the cardiac 

 muscle. 



2. Varying Speed of Cylinder and Effect of Temperature. 



(a.) By means of Gaskell's lever record the form of the heart- 

 beat with varying rates of speed, marking time in seconds in each 

 case (fig. 189). 



FIG. 189. Shows how Heart Curve varies with 

 rate of Drum. In i, 2, 3, T=time in seconds. 

 Gaskell's Lever. 



Fl<3. 190. Shows the effect of Normal Saline 

 directly applied to the Heart (at o, ic 

 and 30 C.). T time in seconds. Gaskell's 



Lever. 



(/;.) Then ascertain effect of temperature on the rate of beat and 

 form of heart curve by applying normal saline, say at o, 15, and 

 30 C., directly to the heart (fig. 190). 



3. Gaskell's Clamp. 



(a.) On a suitable support arrange two recording long light 

 levers of the same length, and with their writing points exactly in 

 the same vertical line, recording on a slow-moving drum, the levers 

 being about 1 2 cm. apart. About midway between the two place 



