VEGETABLE ABSORPTION. 21 



sorption whatever took place. Plants having a 

 fusiform^ or spindle-shaped root, such as the 

 carrot and the radish, are the best for these ex- 

 periments. 



In the natural progress of growth, the roots 

 are constantly shooting forwards in the direction 

 they have first taken, whether horizontally, or 

 downwards, or at any other inclination. Thus 

 they continually arrive at new portions of soil, 

 of which the nutritive matter has not yet been 

 exhausted ; and as a constant relation is pre- 

 served between their lateral extension and the 

 horizontal spreading of the branches, the greater 

 part of the rain which falls upon the tree, is 

 made to drop from the leaves at the exact dis- 

 tance from the trunk, where, after it has soaked 

 through the earth, it will be received by the ex- 

 tremities of the roots, and readily sucked in by 

 the spongioles. We have here a striking instance 

 of that beautiful correspondence, which has been 

 established between processes belonging to diffe- 

 rent departments of nature, and which are made 

 to concur in the production of such remote effects, 

 as could never have been accomplished without 

 these preconcerted and harmonious adjustments. 



The spongioles, or absorbing extremities of 

 the roots, are constructed of ordinary cellular or 

 spongy tissue ; and they imbibe the fluids, which 

 are in contact with them, partly by capillary 

 action, and jjartly, also, by what has been termed 



