9 CHRONICLES OF A CLAY FARM. 



" Into the Air : 



And what seemed corporeal hath melted 

 Like breath into the wind ! " 



The weight, the bulk, the vegetable mass, of a 

 crop, is simply, its Carbon. COMBUSTION just un- 

 does what GROWTH did : and nothing more. It re- 

 combines the Carbon of the plant with the Oxygen 

 of the air, and their union is Carbonic-acid gas: the 

 very substance which the leaves of a plant feed upon 

 in the air where it is presented to them in its gase-. 

 ous form in which alone they can absorb it : they do 

 absorb it ; and in their clever little laboratory, they 

 pick out the carbon and return the oxygen ; just as 

 our own lungs take up the oxygen and return the 

 nitrogen. Multiply the two surfaces of an oak-leaf 

 by the number of leaves on the tree, and you will 

 be able to form some idea of the enormous surface, 

 which the plant annually presents to the atmosphere 

 to carry on this work of absorption. 



But the roots what is their use then? 



Examine them through a Microscope, and you will 

 see that, as the Leaves are adapted to intercourse 

 with AIR, so the roots are adapted to WATER : not 

 stagnant water : for the sponge rots which is always 

 saturated, and their myriad fibers are each furnished 

 at the end with a sponge, capable of rapid expansion 



