34 VEGETABLE POT SONS. 



so material a difference in its effects. If the contractions of lire 

 voluntary muscles had depended on the infusion circulating with the 

 blood, it is reasonable to suppose that the pressure on the aorta 

 'would have occasioned some diminution of them, and that the com- 

 plete obstruction of the circulation would have caused them to 

 cease altogether. 



From these considerations, I am induced, on the whole, to be- 

 lieve that the infusion of tobacco, when injected into the intestines, 

 influences the heart through the medium of the nervous system ; 

 but I have not been able to devise any experiment, by which the 

 truth or fallacy of this opinion might be put beyond the reach of 

 doubt. 



It appears remarkable, that the brain and nervous system, al- 

 though not necessary to the action of the heart, should, when under 

 the influence of the infusion of tobacco, be capable of influencing 

 this organ so as to stop its actiou ; but this is analogous to what we 

 see occur in consequence of violent emotions of the mind. Those 

 states of the nervous system which accompany the passions of joy, 

 tear, or anger, when existing in a moderate degree, render the heart 

 more sensible to the stimulus of the blood, and increase the fre- 

 quency of its contractions ; while, when the same passions exist in 

 a greater degree, the heart is rendered altogether insensible to the 

 stimulus of the blood, and syncope ensues. 



Empyreumatic oil of Tobacco, 



Exp, 13. Less than a drop of this oil was applied to the tongue 

 f a young cat. Instantly violent convulsions took place in all the 

 muscles, and the respirations became very frequent. In five mi- 

 Hutes after the application, she lay on one side insensible, with slight 

 spasmodic actions of the muscles. At the end of eleven minutes 

 she retched, but did not vomit. In a quarter of an hour she ap- 

 peared to be recovering. I repeated the application of the poison, 

 and she was agaiu seized with violent convulsions, and became in 

 sensible, breathing at long intervals ; and in two minutes from the 

 second application respiration had entirely ceased, and she was ap- 

 parently dead. On opening the thorax, 1 found the heart acting 

 with regularity and strength, circulating dark-coloured blood. I 

 introduced a tube into the trachea, and produced artificial respira- 

 tion ; the contractions of the heart became augmented in force anfj 



