72 JSotang 



The foliage not onl}^ prepares food fit for 2:>lant 

 use, but it also prepares air fit for the breathing of 

 animals. The out-breathing of all animals is loaded 

 with carbonic acid gas, which is a poison ; their in- 

 breathing takes from the air oxygen, wdiich is whole- 

 some and valuable for all animals. It is evident 

 that all the air in the w^orld would become loaded 

 Avith carbonic acid gas poison and robbed of useful 

 ox3^gen were not some way contrived to exhaust the 

 one and replace the other. Here the i3lant comes in 

 to restore the balance of affairs. The out-breathed 

 carbonic acid gas is the chief food of the plant w^orld. 

 Oxygen is a drug in the market to plants; a ver}^ 

 small trace of it suffices for their needs. Thus while 

 men breathe out carbonic acid gas and breathe in 

 oxygen, plants do exactly the reverse ; they out- 

 breathe" oxygen and in-breathe carbonic acid gas. 

 Thus the plant and the animal form a mutual bene- 

 fit society, and prepare air that suits all concerned. 

 The green jiarts of the plant, chiefly the leaves, are 

 the agents in this constant reconstruction of the 

 atmosphere. 



Activity for many months in all these directions 

 exhausts the energies of the plant for the time being. 

 The leaves, the stem, the veins become clogged by 

 the abandoned particles of solid matter. This is 

 especially the case in the leaf, stem, and veins. The 



