33 



BOTANY. 



Demonstration 1 4. 



75. To ihow the relation of the root hairs to the other cells of the root. — 



The teacher can make thin sections of young roots, with a razor, through the 

 region of the root hairs, and mount them for microscopic study for demon- 



Kig. 24. 

 Section of corn root, showing rhizoids formed from elongated epidermal cells. 



stration before the class. Let each member of the class sketch a portion of 

 the section, to show the root hairs, their relation to the other cells of the root, 

 as well as some of the characters of the tissues of the root. 



76. Action of the cell-sap. — In the absorption of the watery 

 solutions of plant food by the root hairs, the cell-sap, being a 

 more concentrated solution, gains some of the former, since the 

 liquid of less concentration flows through the protoplasmic 

 membrane into the more concentrated cell-sap, increasing the 

 bulk of the latter. This makes the root hairs turgid, and at the 

 same time dilutes the cell-sap so that the concentration is not so 

 great. The cells of the root lying' inside and close to the base of 



