ABSORPTION OF LIQUID NUTRIMENT. 7 



chlorotic plant with iron solution. The portions treated will become 

 green in a short time, and this color will gradually extend over the 

 plant. 



5. Organs of Absorption. In the lower plants ot simple or- 

 ganization the absorption of nutriment is carried on by a greater 

 part or all of the surface of the organism. In the higher 

 plants the roots are the special organs of absorption, and 

 nearly all of the liquid taken in by the plant is- obtained 

 through them. The marked branching shown in the root sys- 



FIG. 3. 



Cross-section of a root showing structure and arrangement of root-hairs. 

 The latter are swollen in places, applying a broader surface to the soil- 

 particles in contact with them. (Frank.) 



tern of the higher plants not only increases the efficiency of 

 the roots as organs for the fixing of the plant in the soil, but 

 also magnifies the absorbing surface. Absorption is carried 

 on through the outer walls of the peripheral cells which con- 

 stitute the epidermis. In land plants the outer walls of these 

 epidermal cells are developed into long tubelike extensions, 



