THE ROOT AND ITS FUNCTIONS 



43 



of several millimeters and forces its way into the minute crevices 

 of the soil, thus coming into most intimate contact with the soil 

 particles (Fig. 26). Through the enormous surface which these 

 root-hairs expose to the soil, absorption of water and mineral 



Fig. 24. — Root-hairs and their relation to the root. A transverse section 

 across the root-hair zone, showing the attachment of the hairs. In the root may 

 be distinguished the fibro-vascular cylinder (in the center), surrounded by the 

 cortex. 



Cy+oplc 



Nucleus 



Fig. 25. — A root-hair. Section through a typical root-hair, showing its various 

 structures and its relation to the surface cells of the root. 



salts takes place. Root-hairs are generally short-lived, dying 

 away as the corky bark begins to appear. A root-hair zone of 

 fairly constant length thus follows behind the growing root-tip, 

 new hairs appearing in its younger portion to replace the oldest 

 ones, which arc continually dying away. 



