62 LIFE IN NATURE. 



of vibration: but in order that it may do so that action 

 must take place under resistance, or must be incom- 

 plete. The pendulum rises from the effect of its fall, 

 because that fall is partial, and fails of reaching the 

 attracting body. If it fall to the earth, though the law 

 of its action and the total amount of the effect pro- 

 duced are the same, yet the practical result is dif- 

 ferent. Other forces, such as heat and sound, are 

 produced, but the raised condition of the falling body 

 does not re-appear. It is the same with the vibra- 

 tions of a string; the tension which is necessary 

 before vibration can be induced in it seems to intro- 

 duce a resistance to the full recoil of the particles 

 upon each other, so that their partial return after 

 being drawn aside carries them again asunder. Now 

 a similar thought respecting the chemical action 

 which is the cause of growth, seems to be appropriate 

 to, and demanded by, the facts. Living matter ap- 

 pears to afford such a limitation to chemical change, 

 when taking place in relation with it, and so it 

 educes a vitalizing action from that change. It 

 gives this direction to the force generated by decom- 

 position, or by other processes of chemical union, by 



