LECTURE V. 227 



system, we seem warranted in concluding, 

 as Mr. Hunter has done, that the different 

 degrees of power allotted to different 

 parts of the arterious system, is given to 

 them for the purpose of aiding in carrying 

 on the circulation. 



When the blood is projected by that pow- 

 erful engine, the heart, into the large arte- 

 ries, little energy on their part is requisite 

 to urge on the rapid current ; but in pro- 

 portion as the heart's influence diminishes, 

 power is allotted to the vessels to aid in its 

 propulsion. There are some modern physio- 

 logists, and those of high repute, who con- 

 glider the heart, by its actions alone, as fully 

 adequate to maintain the circulation, and 

 consequently discredit the irritability of arte- 

 ries, except of those which are called capil- 

 laries. But where, I would ask, am I to sup- 

 pose that these capillaries begin ? I cannot 

 observe the sudden and deep blush of sh^ne, 

 or extreme paleness of terror, without being 

 convinced that arteries of no inconsiderable 

 size possess vital activity; we cannot believe 

 that the heart's influence can be partially 



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