No. 144.] 305 



tinually occurring both with the plant and the soil in which it 

 grows, for the evaporation of water from the surface of the soil 

 cools the water below the surface to the proper temperature for 

 the use of plants. 



Different parts of the organism of the plant are discharging ex- 

 cretia, which can only be carried down through water, while 

 excess of pabulum existing in one part of the plant is by means 

 of water' transferred to another part where it is required for ap- 

 propriation, but the necessity for the presence of water does not 

 end here, for in the atmosphere and in the soil it is the prime 

 motor for the re appropriation of the ultimate results from de- 

 caying nature, thus the dews and rains as they fall through the 

 atmosphere wash from it and carry to the soil ammonia, carbonic 

 acid, &c., and with them are received into the roots of plants, 

 where these constituents are appropriated, while the aqueous 

 portion passes through the plant, performing its lubricating offices, 

 and is parted with at the surface for the purposes we have before 

 named. 



In the soil the presence of water is not less important. It car- 

 ries to the soil the heat it receives from the atmosphere, and in 

 its evaporation from the surface of the soil it carries off the excess 

 of this heat, and such other quantities as may be received from the 

 direct action of the sun's rays on the surface of the soil. 



From the expansion and contraction of water during freezing 

 and thawing, it exerts a mechanical action in the disintegration 

 of soils, rocks, &c. After such disintegration it carries the con- 

 stituents rendered soluble by chemical changes, consequent upon 

 the presence of moisture, so as to bring these constituents in con- 

 tact with others, and thus new chemical actions are engendered, 

 and new compounds formed, such as may be required to prepare 

 inorganic food for plants. 



The roots of former crops, by the presence of moisture, are 

 slowly rendered soluble, and their integrants are carried in a 

 state of solution into the roots of the new growing crops. By the 

 presence of this medium, each chemical product is more evenly 



[Assembly, No. 144.] T 



