LIV.] 



SUSPENSION METHODS FOR HEART. 



267 



By this method, also, the efifect 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 Gaskcll's lever record the form of the heart- 

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

 case (fig. 189). 



Fia. 189.— Shows how Heart Curve varies witn 

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

 Gaskell's Lever. 



FlO. 190. — Shows the effect of Normal Saline 

 directly applied to the Heart (at 0°, 15' 

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

 Lever. 



{b.) 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 



