CHEMICAL DECAY. 935 
nature of the one part more easily and quickly 
yields to them, than the firmer and drier 
nature of the woody tissues permits the other 
to do. 
This change has been already described in a 
previous page, in alluding to the cause of the 
decay in the trunk of the tree. It is, as has 
been before said, the wind and the rain which 
produce the crumbling down of the firmest strue- 
tures of the vegetable world. These simple and, 
in our eyes, weak and inefficient agencies, are 
the Divinely appointed means whereby the dead 
portions of plants, or the dead trunks of entire 
trees, are, without fail, to be restored in a com- 
mon but altered form to the bosom of the earth ; 
nor can any vegetable structures long resist their 
operations. By their means the materials long 
since taken from the soil, in the shape of alkalis, 
salts, and mineral ingredients, are all safely restored 
again. During the period of its existence the 
plant may indeed accumulate within itself a very 
large portion of these substances, and in pro- 
portion impoverish the soil in which it grows. 
If these substances were to be no more restored 
to the soil again, it would by and by become 
