50 EFFECTS OF 



tobacco renders the heart insensible to the 

 accustomed stimulus, but it does not altogether 

 destroy the power of muscular contraction, since 

 the heart resumed its action in one instance 

 on the division of the pericardium ; and I have 

 found that the voluntary muscles of an animal 

 killed by this poison, are as readily stimulated to 

 contract by the influence of the Yoltaic battery, 

 as if it had been killed in any other manner. At 

 the same time, however, that the infusion of 

 tobacco destroys the action of the heart, it ap- 

 pears to destroy also the functions of the brain, 

 since these did not return in the last experi- 

 ment; although the circulation was restored, 

 and kept up by artificial respiration. 



There being no direct communication between 

 the intestine and the heart, I was at first in- 

 duced to suppose that the latter becomes affected 

 only in consequence of the infusion being con- 

 veyed into the blood. Some circumstances in 

 the following experiment have since led me to 

 doubt whether it may not exercise an influence 

 over the system independently of absorption. 



EXPERIMENT XII. 



In a dog, whose head was removed, I kept up 

 the circulation by means of artificial respiration, 

 in the manner already described in a former com- 

 munication to this Society. I then injected into 

 the stomach and intestines nine ounces of infusion 

 of tobacco. At the time of the injection, the body 



