SEQUENCE OF CONTRACTION IN THE HEART. 529 



which was exposed to view, were pulsating. The veins, as well 

 as both auricles, pulsated at the rate of 119 per minute, but the 

 contractions of the veins were not synchronous with those of 

 the auricles. Both auricles next ceased to beat, but the pul- 

 monary veins in both lungs continued to pulsate. The ventricles 

 now began to beat again, while the auricles remained still. The 

 ventricles pulsated at tlie rate of 8 per minute, while the pul- 

 monary veins pulsated at the rate of 46 per minute ; and no 

 motion was perceptible in any part of the auricles. 



One hour and twenty minutes after the thorax had been 

 opened, and about an hour and ten minutes after artificial 

 respiration had been discontinued, the ventricle was still pul- 

 sating. Its rliythm was very irregular. After one beat a pause 

 of half a minute followed, and then 37 pulsations all together. 

 One hour and forty minutes after opening the thorax the inferior 

 vena cava was noticed to be pulsating close to its entrance into 

 the auricle. A contraction spread like a wave from the vena 

 cava over the right auricle, and the appendix contracted after 

 the auricle itself. The superior vena cava also pulsated close to 

 the neart. The left auricle had ceased to pulsate a considerable 

 time previously, and the ventricles liad also stopped. After the 

 auricles had pulsated for a while the ventricles again began. 

 At one hour and fifty minutes ai"ter opening the thorax the 

 inferior vena cava was still pulsating. In ten minutes more all 

 movement had nearly ceased, and the observation was discon- 

 tinued. 



At one hour and fifty minutes after opening the thorax slight 

 contractions of the diaphragm were noticed. 



The striking points in this experiment are the contractions of 

 the pulmonary veins and the vena cava independently of the 

 heart, the long time during wdiich they retained their irrita- 

 bility, and the continuance of their pulsations after the other 

 parts of the heart had ceased. The pulsation of the pulmonary 

 veins and of the ventricles at the same time, while the auricles 

 were motionless, is also deserving of attention. 



In another experiment we found the pulmonary veins pulsat- 

 ing in a cat killed by a blow on the head. We have also seen 

 pulsation in animals killed in other ways ; but the proportion of 



2 M 



