ELEMENTARY EXPERIMENTAL PHYSIOLOGY 



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normal level in the cat. In the hutch rabbit the pressure falls, until 

 the medullary centres become paralysed from anaemia. The weight of 



FIG. 142. Record of arterial pressure and respiration (A) before and (B) one minute 

 after dividing the vagi. The upstroke marks inspiration. The arterial pressure rose 

 from 150 to 180mm., the pulse rate from 110 to 260. Respiration fell from 24 to 10. 

 The expirations became strenuous. (Burdon Sanderson.) 



FIG. 143. The effect of excitation of the peripheral end of the vagus nerve upon the 

 blood pressure in the aorta (top curve) and the vena cava (second curve) of a curarised 

 animal with artificial respiration. Note the inhibition of the heart ; the great fall of 

 aortic and the insignificant rise of vena cava pressure ; the escape of the heart from the 

 vagus action and the after effect on the aortic pressure. The time is marked in seconds, 

 and the signal line shows the duration of vagus stimulation. (L.H.) 



