214 TRANSACTIONS OF THE ILLINOIS 



becoming living substance. To do this is the peculiar office of the plant, 

 working under the influence of the solar rays. 



The sun in some way supplies the power which enables the living 

 plant to originate these chemical combinations ; to organize matter into 

 forms which alone are capable of being endued with life. The process 

 is all the same, whether the plant is making direct growth or laying up 

 stores for future use. The principal ingredient laid up by plants is starch, 

 in the form of minute grains, in the cells of the plant. All plants, in a 

 general sense, receive their food from the roots ; the tree receives its 

 supply of minerals, such as silex, lime, potash, magnesia, etc., in solution ; 

 the sap thus charged with nourishment ascends the trunk, traverses the 

 branches, and passes into the leaf. The superfluous sap, which held the 

 nourishment in solution, passes off by respiration of the leaf, but does not 

 part with the nutriment contained in the liquid. 



The wonderful system of minute vessels which traverse the whole cell- 

 ular tissue becomes clogged as the season advances ; its circulating func- 

 tions gradually cease to operate, and long before winter, they are wholly 

 suspended. The leaf loses its hold and falls to the ground. The charac- 

 ter of plants in the various countries of the earth is much influenced by 

 peculiarities of soil, temperature, and other local influences. Plants hav- 

 ing an abundance of expansive foliage are apt to be natives of a humid 

 atmosphere. Asiatic plants have been noted for their beauty, African for 

 their fleshy, succulent leaves, and American for smoothness of their foli- 

 age and the singularity of shape in flower and fruit. Plants indigenous 

 to polar or mountainous regions are generally low, with small, compressed 

 leaves, but flowers large in proportion. Australian plants are distinguish- 

 able for small, dry, shriveled leaves. In Arabia, they are low and dwarf- 

 ish ; in the Indian Archipeligo, shrubby and prickly. 



Shrubby plants of the Cape of Good Hope, and Australian plants, 

 exhibit a striking similarity, also the plants of Northern Asia and Amer- 

 ica. All this variety is undoubtedly the result of the food taken up by 

 the roots or foliage, whether it be mineral or gaseous nutriment, governed, 

 of course, by climatic influences. 



It is a very well known principle that the grain, and other fast grow- 

 ing plants used for food by man and animal, require a rich, strong soil. 

 By rich soil, we understand a soil possessing an excess of the decomposed 

 organic matter that enters the composition of the plant in its new combi- 

 nation. 



" The soil and the air upon which plants live, and by which they 

 are everywhere surrounded, supply a variety of materials — some likely 

 to be useful to the plant, others not." Hence, to know what elements a 

 plant can use as food, we must know its chemical constituents and its 

 general composition. If we decompose or burn a plant, we find it all 

 dissipate, and pass off" into the atmosphere, except an earthy residue, 

 termed ashes. Plant food must contain carbon, oxygen, and hydrogen, 

 in some form or other. Plants absorb more water than any thing else ; 

 hence the most ignorant cultivator applies water, not knowing the elements 



