STIMULATION AND PARALYSIS OF THE VAGUS. 



507 



I 



Post mortem (immediately after death). — The heart contained 

 blood, and contracted on puncture. The auricles contracted for 

 3 minutes after death. 



This experiment shows that the action of a small dose of 

 casca is to raise the blood-pressure and slow the heart at first. 

 Next, when the heart becomes very slow, the pressure falls, and 

 finally the heart ceases to beat, and death takes place. 



The cardiac pulsations remained slow from the time of the 

 injection of the casca up till death ; and although they at one 

 time rose from 1 pulsation in 30 seconds up to 5 pulsations in 

 10 seconds, they never came at all near to the normal, which in 

 this animal was 18^ pulsations in 10 seconds. 



The very slow pulse here indicates that the vagus is prob- 

 ably stimulated by the casca; and the continuance of the 

 blood-pressure at the height of 65 mm. during a cardiac 

 diastole, lasting for 30 seconds, shows unmistakably that the 

 arterioles are strongly contracted by the drug. 



Action on Vagqs. 



Maximum Irritation, 



Experiment XXXV. — March 4. 



A cat, weight 4 lb., was chloroformed, and a cannula was 

 placed in the left carotid artery and in the left femoral vein. 



* Tlie mark ° here signifies distance in cm. between primary and secondary 

 coils in Du Boia Eejmond's induction-apparatus. 



