PHENOMENA OF PLANT-LIFE. 9 



and then, by the expansive power of growth, enlarge these 

 capillary channels to any required size. 



Roots of ordinary plants grow most freely in a loose, well- 

 drained soil, containing the essential elements of plant-food in 

 a soluble form. They absorb their water from the surface of 

 the molecules of the soil, to which they attach themselves by 

 very minute, cellular papillae, called root-hairs. These hairs 

 are much more numerous in a soil moderately dry than in 

 one which is wet and heavy. The most vigorous plants have 

 the largest number and greatest extent of roots. Hence 

 the importance of deep and thorough tillage in preparing the 

 ground for crops. The growth of a plant depends chiefly 

 upon the amount of water which is exhaled by its leaves, and 

 this necessarily depends upon the supply furnished by the 

 the roots. The folly of ploughing between rows of corn, or 

 other plants, after their roots have spread widely through the 

 soil, is self-evident. Prof. L. B. Arnold says he has known 

 the maturing of a corn-crop postponed ten days by ploughing 

 it at the last hoeing. 



The penetrating power and tendency of roots is well illus- 

 trated in the case of an apple-tree on the College farm, which 

 forced its roots down through a mass of coarse gravel eight 

 feet, to obtain a supply of water. The stones were about the 

 size of hens' eggs, and so closely packed by the waters of the 

 drift period which deposited them, that the cylindrical form 

 of the roots was entirely destroyed. The growing tissues 

 pressed themselves into every crevice so as actually to 

 surround and enclose the adjoining pebbles. (Fig. 17.) A 

 similar root of an elm was recently dug up in Westfield, Mass., 

 and presented to the College museum by Mr. B. H. Averell. 

 Prof. Stockbridge, last fall, washed out a root of common clo- 

 ver, one year old, growing in the alluvial soil near the Connec- 

 ticut River, and found that it descended perpendicularly to the 

 depth of eight feet. Mr. Mechi, of Tiptree Hall, England, 

 tells us that the reason clover is usually so short-lived, is the 

 fact that the lower roots are either unable to penetrate the 

 subsoil or to find in it the requisite supplies of food. He 

 also states that his neighbor, Mr. Dixon, of Riven Hall, dug 

 a parsnip which measured thirteen feet six inches in length, 

 but, unfortunately, was broken at that depth. 



