30 LIFE IN NATURE. 



structure, and will bear a very much greater strain 

 without rupture thau in its uncontracted state. 



The causes which determine contraction in a 

 muscle are those which induce its decomposition. 

 When placed beneath the microscope, it is seen to 

 contract first at any spot -where it has been broken 

 or otherwise subjected to injury. The slightest 

 mechanical irritation induces a local contraction, as 

 does also the contact of air or water. In cases of 

 lingering disease, in which the proneness to decay 

 is increased, contraction of the muscles takes place 

 with increased facility, and may often be excited 

 by a touch. And the stimuli which, in health, 

 induce action in the muscles most powerfully, are 

 those which most strongly evoke their tendency to 

 change of composition. Electricity, which ranks 

 next to the nervous force as the exciter of muscular 

 action, stands first among the physical forces as a 

 promoter of chemical change, and is known to induce 

 the speedier decomposition, after death, of muscles 

 to which it has been freely applied. 



But we must pass by many inviting topics, and 

 hasten to notice one objection to the view that has 



