206 



THE CONTRACTION OF CARDIAC MUSCLE. 



FIG. 110. Heart of toad. Suspension method. Ventricle only registered. Long stimu- 

 lation of the intracranial vagus roots with moderately strong current. 





FIG. 111. Heart of toad. Suspension method. Clamp in auriculo-ventricular groove. 

 Stimulation of augmentor (sympathetic) nerve before it joins the vagus. 



FIG. 112. Heart of toad. Suspension method. Clamp in auriculo-ventricular groove. 

 Stimulation of vagus (i.e. vago-sympathetic) nerve in neck. 



FIG. 113. Heart of frog. Suspension method. Clamp in auriculo-ventricular groove. 

 Stimulation of the vagus in the neck (i.e. the combined vagus and sympathetic nerve), 

 showing the effect of the simultaneous stimulation of the two nerves. 



