ELEMENTARY DEMONSTRATIONS 



133 



Stimulate the peripheral end of the vagus nerve. The heart is 

 inhibited, and the arterial pressure falls. Complete arrest cannot be 



FIG. 112. Record of arterial pressure (AP) and plethysmogram of limb (volume 

 record LV). Excitation of the depressor nerve at signal A. The limb expanded in 

 spite of the fall of arterial pressure. The time is marked in seconds. (Bayliss.) 



obtained in the cat. It is easily obtained in the dog. In the chloro- 

 formed dog with low blood-pressure, vagus excitation, produced by 



FIG. 113. Hill's animal table. The table can be raised or lowered at one end, or1>e reversed. 



inhalation of concentrated chloroform vapour, may arrest the heart 

 for so long a period as to kill the animal. This is one cause of chloro- 

 form syncope in man. The heart soon escapes from vagus arrest if 



