VASCULAR AND RESPIRATORY ORGANS. 201 



(Etherisation must be maintained, otherwise the animal might 

 suffer pain. Why?) 



While maintaining the artificial respiration the sciatic and 

 vagus nerves are stimulated as before. What conclusions can be 

 drawn from the results? 



The effect of asphyxia on the arterial blood pressure is then 

 studied, the asphyxia being induced by suspending the artificial 

 respiration. How do the results compare with those observed 

 during asphyxia with the vagi intact? After the blood pressure 

 has finally fallen to zero the thorax is opened and the heart ex- 

 amined. Extreme venous engorgement is observed. Note the 

 behaviour of the heart when the engorgement is relieved by punc- 

 turing the right ventricle. What conclusions do the observations 

 warrant? 



