88 



EXERCISE XIV 



with a weak current, not much above the strength which just elicits 

 muscular contraction when the electrodes are applied directly to some 

 muscular surface exposed in the wound, e.g. 15 cm. on the inductorium 

 scale may be about the strength. Note the ensuent gradual though 



Text-fig. 33. Arterial-pressure record showing depressor reflex evoked from the n. 

 depressor ; decerebrate preparation (H. V. Forster and C. S. S.). a.p., carotid pressure 

 by Hg manometer ; z, zero-line of manometer pressure ; t, time in 3" intervals ; s, signal-line 

 showing time of faradization of central end of severed n. depressor. 



somewhat rapid decline of the mean pressure (text-fig. 33). 

 slight slowing of the heart's frequency. 



There may be a 



Obs. 70. 

 Reflex cardiac 

 inhibition. 



VI. Faradize similarly the central end of the prepared vagus 

 trunk. Note the ensuent decline of the carotid mean pressure. There is 

 almost always a slowing of the heart's frequency. 



Faradize the vagus with slightly increased strength of current ; distinct 

 slowing of the heart's frequence will, if not evident before, become evident. 

 This is reflex cardiac inhibition through the cardio-inhibitory centre in 



