222 LECTURE V. 



that which he delivers. I shall therefore 

 merely tell you what I have been taught by 

 Mr. Hunter to think with respect to the 

 principal parts of the subject of the distri- 

 bution of nourishment in the higher classes 

 of animals. 



First, then, I find Mr. Hunter examining 

 the structure of the arteries or tubes by 

 which the blood appears to be carried to 

 every part of the body. He is neither 

 clear nor confident in his description of 

 them ; and yet I know not that any one 

 has described them better. Internally they 

 are membranous tubes, which is a com- 

 mon character of all sorts of vessels, the 

 polished surface of the membrane admit- 

 ting their fluid contents to pass along with 

 the greatest facility. He knew that exte- 

 rior to this, and not far from it, there was 

 some substance, thin, but particularly strong 

 and unyielding, which caused the vessel to 

 have a regular circular form when distend- 

 ed. He found that when the trunk of the 

 distributive vessels, the aorta, was injected 

 with a force equal to ninety pounds, this 



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