CHAPTEE VI 



OF THE MUSCLES OF MUSCULARITY AND ELAS- 

 TICITY 



THERE are two powers of contraction in the 

 animal frame elasticity, which is common to 

 living and dead matter, and the muscular power, 

 which is a property of the living fibre. 



The muscles are the only organs which properly 

 have the power of contraction, for elasticity is 

 never exerted but in consequence of some other 

 power bending or stretching the elastic body. In 

 the muscles, on the contrary, motion originates ; 

 there being no connection, on mechanical princi- 

 ples, betwixt the exciting cause and the power 

 brought into action. 



The real power is in the muscles, while the safe- 

 guard against the excess of that power is in the 

 elasticity of the parts. This is obvious in the 

 limbs and general texture of the frame ; but it is 

 most perfectly exhibited in the organs of circula- 

 tion. If the action of the heart impelled the 

 blood against parts of solid texture, they would 

 quickly yield. When, by accident, this does take 

 place, even the solid bone is very soon destroyed. 



