136 ADDITIONAL NOTES. 



mentioned poisons. The action of the diaphragm 

 continues after that of the heart has ceased, and 

 the animal dies with scarlet blood, in the left 

 cavities of the heart and in the aorta. This 

 fact has been ascertained by Dr. Chossat and 

 myself, and may be of some practical importance, 

 inasmuch as it has been proved by one of my 

 experiments with the infusion of tobacco, that 

 under these circumstances there is a possibility 

 of the action of the heart being restored, which 

 never can happen when the circulation of dark- 

 coloured blood has continued after respiration 

 has ceased. 



In the true angina pectoris, depending on ossi- 

 fication of the coronary arteries, it is probable 

 that death takes place in the same way. The 

 supply of scarlet blood to the muscular structure 

 of the heart by these vessels is sufficient for ordi- 

 nary purposes, but when, under the influence of 

 mental emotion, or from other causes, the heart 

 is required to make any unusual exertion, the 

 supply is insufficient, and its action ceases. Mr. 

 Hunter, however, who laboured under this dis- 

 ease, supposed that on one occasion he kept him- 

 self alive by a forced or voluntary act of re- 

 spiration, after ordinary respiration had been 

 suspended. 



The most marked symptom of ordinary 

 syncope is the failure of the pulse, and it is not 

 improbable that in some instances the heart 

 entirely ceases to act, though it resumes its 

 action afterwards. 



