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EXPERIMENTAL PHYSIOLOGY 



be now closed and the one containing the piston opened, the piston 

 will move to and fro, and its movements can be recorded on a very 

 slowly rotating horizontal drum. 



It may happen that the perfused heart (which is a Stanniused heart) does not 

 begin to beat spontaneously, although the salts and the pressure of fluid serve 

 as a slight stimulus. In that event the beats may be started by faradic excita- 

 tion from an induction coil, one electrode being attached to the metal cannula 

 and the other to a wire which passes up through a cork in the bottom of the 

 plethysmograph, and is brought in contact with the ventricle. 



The influence of various salts, such as chloride of calcium and chloride of 

 potassium, of anaesthetic agents such as ether and chloroform, and of drugs such 



