188 NATURAL THEOLOGY. 



derable degree of elasticity to the whole frame. 

 Without such elasticity, a jar would reach the 

 more delicate organs, even in the very recesses of 

 the body, at every violent motion ; and, but for 

 this provision, every joint would creak by the at- 

 trition of the surfaces of the bones. The bones are 

 surrounded with the flesh or muscles. The mus- 

 cle is a particular fibrous texture, which alone, of 

 all the materials constituting the frame, possesses 

 the peculiar inherent power or endowment of con- 

 tracting : it is this power which we are to under- 

 stand, when professional men speak of irritability. 

 The contraction of the muscle bears no proportion 

 to the cause which brings it into operation, more 

 than the touch of the spur upcn the horse's side 

 does as a mechanical impetus to the force with 

 which the animal propels both himself and rider. 

 Each muscle of the body — and by common esti- 

 mate there are hundreds — is isolated; and no 

 property of motion is propagated from one to an- 

 other ; they are distinct instruments of motion. 

 The muscles surround the bones, and are so beau- 

 tifully classed, that in every familiar motion of the 

 limbs some hundreds of them are adjusted in their 

 exact degree,, to eftect the simplest change in the 

 positioa of the body. 



Each fibre of a muscle, and a muscle may con- 

 tain millions of fibres, is so attached to the tendon, 

 that the whole power is concentrated there ; and 

 it is the tendons of the muscles which, like ropes, 

 convey the force of the muscles to the bones.. The 



