GRAPHIC OF ARTERIAL PRESSURE 



37 



will take place. Following this there usually occurs (text-fig. 18) a change 

 in the rate of the heart-beat, the rate falling suddenly to one-half, and then 

 sometimes again suddenly to one-third or one-quarter. This is due to 



Text-fig. 17. Arterial-pressure record showing eifect of intravenous "injection of 

 adrenal extract ; decapitate preparation (D. Collier and W. Peacey). a.p,, carotid pressure ; 

 z, zero-line of Hg manometer ; s, signal-line showing time of injection of adrenal extract ; 

 T, time in 2" intervals. 



heart-block, the ventricle responding only to every second or at a later 

 stage every third beat of auricle. When this heart-block has occurred and 

 lasted for a few seconds it is time to relieve the asphyxial condition, 



