THE VEGETATIVE ORGANS OF PLAOTS. 239 



apple, peach, and other trees, when very young, in order 

 that they may be readily and safely transplanted as occa- 

 sion shall require. The depth and character of the soil, 

 however, to a certain degree influence the extent of the 

 roots and the tenacity of their hold. The roots of maize, 

 which in a rich and tenacious earth extend but two or three 

 feet, have been traced to a length of ten or even fifteen 

 feet in a light, sandy soil. The roots of clover, and espe- 

 cially those of lucem, extend very deeply into the soil, 

 and the latter acquire in some cases a length of 30 feet. 

 The roots of the ash have been known as much as 95 feet 

 long. (Jour. Roy. Ag. Soc. 9 VI, p. 342.) 



2, Root-absorption. The Office of absorbing Plant 

 Food from the Soil is one of the utmost importance, and 

 one for which the root is most wisely adapted by the fol- 

 lowing particulars, viz.: 



a. The Delicacy of its Structure, especially that of the 

 newer portions, the cells of which are very soft and absor- 

 bent, as may be readily shown by immersing a young 

 seedling bean in solution of indigo, when the roots shortly 

 acquire a blue color from, imbibing the liquid, while the 

 stem, a portion of which in this plant extends below the 

 seed, is for a considerable time unaltered. 



It. is a common but erroneous idea that absorption from 

 the soil can only take place through the ends of the roots 

 through the so-called spongioles. On the contrary, the 

 extreme tips of the rootlets cannot take up liquids at all. 

 (Ohlerts, loc. cit., see p. 249.) All other parts of the roots 

 which are still young and delicate in surface-texture, are 

 constantly active in the work of imbibing nutriment from 

 the soil. 



In most perennial plants, indeed, the larger branches of 

 the roots become after a time coated with a corky or oth- 

 erwise nearly impervious cuticle, and the function of ab- 

 ^orption is then transferred to the rootlets. This is demon- 



