274 THE LAWS OF ORGANIC 



belonging to the peritoneum or intestines be- 

 ing affected ; the latter brings forward a contrary 

 opinion, supported by direct experiment, in which 

 he attempts to show, that opium applied to the 

 coats of the blood-vessels destroys their muscular 

 power, and therefore must " influence the motion 

 of the heart, by impeding, or entirely interrupt- 

 ing, that of the blood, in nearly one-third of the 

 whole animal."* 



This explanation is very ingenious, but far 

 from being correct. He supposes that the heart 

 becomes immediately affected from the muscular 

 power of the capillary vessels being destroyed, 

 preventing the usual quantity of blood being trans- 

 mitted to the heart. To shew that it does not, 

 by any means, depend on this cause, I removed 

 the intestines in Experiments VII. IX. and X. 

 and applied a stimulus to the vena cava, just 

 above the pelvis, and found that the motions of 

 the heart were almost instantaneously quicken- 

 ed, and, still further, that the effect in some de- 

 gree was proportionate to the vicinity of the vein 

 acted upon to the heart. By applying the agent 

 to large vessels, we cannot suppose we either 

 paralyse or stimulate the coats, so as to affect indi- 

 rectly the circulation ; and therefore the stimulus 

 or sedative must be conveyed by the absorbents 

 or blood-vessels. 



* A Treatise on Febrile Diseases, Vol. IV. p. 685. 



