PHYSIOLOGY OF ORGANIC LIFE. 115 



Iciousness resides, \ve are totally ignorant of 

 the manner by which its actions are displayed ; 

 how it is, that without being muscular in its 

 fabric, it is, nevertheless, the cause of muscular 

 motion ; how, though formed of parts which 

 were originally destitute of sense and of reason, 

 it, nevertheless, constitutes the instrument from 

 which the principles of sense and of reason 

 perpetually flow. Notwithstanding all analogy 

 justifies the opinion that the brain is an organ of 

 secretion, the fact has never been demonstrated, 

 and the most perfect ignorance exists, at this 

 time, how, this most important organ of the 

 whole system acts, and what is its nature. 

 This state of ignorance has been very candidly 

 confessed by Sir Busic HARWOOD, the present 

 learned and respectable professor of anatomy 

 at the university of Cambridge : " When we 

 dissect the brain," says he, " and observe the 

 different substances of which it is composed, 

 and their different forms ; imagination, assum- 

 ing the office of reason, would willingly assign 

 a peculiar use to every part, and pronounce 

 one to be the residence, or rather the instrument 

 of memory; another of abstraction, a third of 

 volition, &c. When a sensation is excited by 

 the action of any substance upon the body, we 

 immediately perceive upon what part of the 

 body, the substance acts, where the impression 

 begins ; and as the impression is conveyed by 



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