244 LECTURE VI. 



the circulating fluids are called the secern- 

 ing vessels. It is curious to observe Mr. 

 Hunter's expressions with regard to these 

 agents. " I would not," says he, " call 

 them arteries ; they are workers, they are 

 the labourers." He would not consider 

 them as concerned in the circulation of the 

 blood, they are the chemists and the archi- 

 tects of the body. That such vessels could 

 separate from the blood something that 

 was formally present in that fluid, might be 

 easily credited. But how they could pre- 

 pare that extreme diversity of fluids and 

 substances which they are known to do, 

 formed a problem that was never solved till 

 the time of Hunter. He thought that the 

 vital principle of the vessel, acting on that 

 of its fluid contents, produced these che- 

 mical changes. He thought that there was 

 a correspondence or concert of affection and 

 action between them, a harmony as he calls 

 it. Thus did l,ie attempt to explain how a 

 morbid state of fluids could induce an un- 

 healthy action of vessels, and how the latter 

 could reciprocally occasion the former. Was 

 he not, indeed, a strong and clear-sighted 



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