VEXUS'S FLY-TRAP. 65 



that of the leaf is so wonderfully complete, that the 

 further we pursue the inquiry the more striking does 

 it appear. Whether we bring the microscope to bear 

 on the structural changes which accompany contrac- 

 tion, or employ the still more delicate instruments 

 of research, which you have before you this evening, 

 in order to determine, and measure, the electrical 

 changes which take place in connexion with it, we 

 find that the two processes correspond in every 

 essential particular so closely, that we can have no 

 doubt of their identity. 



" Muscle, like every other living tissue, is the seat, so 

 long as it lives, of chemical changes, which if the 

 tissue is mature, consist entirely in the disintegration 

 of chemical compounds and the dissipation of the 

 force stored up in these compounds, in the form of 

 heat or some other kind of motion. This happens 

 when the muscle is at rest, but much more actively 

 when it is contracting, in which condition it not only 

 produces more heat than it produces at other times, 

 but also may do — and under ordinary circumstances 

 does — mechanical work ; these effects of contraction 

 of muscle are, of course, dependent in quantity on the 

 chemical disintegration which goes on in its interior. 



"Again, muscle, so long as it is in the living state, is 

 electromotive. This property it probably possesses 

 in common with other living tissues, for it is very 

 likely that every vital act is connected with electrical 



F 



