LECTURE I. 25 



blood on our coloured injections, so that 

 redness though a comm 

 tial character of muscle. 



redness though a common is not an essen- 



I here willingly relinquish the enquiry 

 into the structure of those organs in which 

 the irritable property chiefly resides, in 

 order, in the next place, to speak of the 

 principal phsenomena of irritability. 



Muscles have the power of contracting 

 with surprising celerity and force. It seems 

 indeed wonderful that the biceps muscle of 

 the arm, which in the dead state would be 

 torn by the weight of a few ounces ap- 

 pended to it, shall in the living state be 

 capable of lifting and sustaining more than 

 100 lbs. The matter in the muscle seems 

 neither to be increased nor diminished 

 during its contraction, what is lost in 

 length being gained in bulk. The volun- 

 tary contraction of muscles cannot be long 

 continued ; they become weary and pain- 

 ful, the contraction remits and recurs, 

 causing a tremulous motion. Yet this 

 phaenomenon does not seem to be the 



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