VENTRICLE STIMULATION 



77 



A signal may be arranged as in Less. XII, 3, to write on the 

 drum, and the key closed for a moment as each drop falls. Thus a 

 record may be obtained of the rate of flow. 



2. The heart which was placed in saline solution will 

 probably not be beating, but it may be beating slowly. 

 Arrange a lever to write on the drum, and connect the 

 heart to the lever as in Less. XII, 1. Pin the sinus to 

 the frog board. Pin thin wire electrodes to the stand, 



Fig. 24. 



arrange the points to touch two sides of the ventricle 

 near its tip, and connect for single induction shocks. 

 Move up the secondary coil till a contraction is obtained 

 at make and break. When stimulating, the key must be 

 opened and shut quickly and steadily. Set the drum 

 moving slowly. 



a. If the heart is not beating : 



Stimulate with a make and after a few seconds with a 

 break current ; a single contraction is obtained with each 



