206 



THE CONTRACTION OF CARDIAC MUSCLE. 



Excitation Signal 

 ji_jij_ji_ji_n_rLJLJLJi_n-ji_n-JL^ 

 Time in. Seconds 



Fig. 110. — Heart of toad. Suspension method. Ventricle only registered. 



lation of the intracranial vagus roots with moderately strong current 



Long stimu- 



_A_JLAJULJl_n_n_nJlJlJLJLJLAJlJUUL 



Time in Seconds . MillUU\\U\U\\\\\\\\\\\M\\U\\U\U\UU\UUU\\UU\UUtl«ii»i»' ,, '. ... . 



Ventricle 



m\mmmmimmNmmmmmmmmwmw 



mmwwmmw 



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. 



Au.r. 



^mmmwMM 



' IlK i ___^aaI' 



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. 



