ROOT HAIRS 



145 



is made up of cellulose. Clinging close to the cell wall is the pro- 

 toplasm of the cell, the outer border forming a very delicate 

 membrane. The interior of the 

 root hair contains many vacuoles, 

 or spaces, filled with a fluid called 

 cell sap. Forming a part of the 

 living protoplasm of the root hair, 

 sometimes in the hairlike prolonga- 

 tion and sometimes in that part 

 of the cell which forms the epi- 

 dermis, is found a nucleus. The 

 nucleus, the membrane, and the rest 

 of the protoplasm are alive ; the cell 

 wall, formed by the living matter in 

 the cell, is dead. The root hair is 

 part of a living plant cell with a 

 membrane and wall so delicate that 

 water and dissolved mineral substan- 

 ces from the soil can pass through them into the interior of the root. 

 Functions of the root hairs. If a root containing a fringe of 

 root hairs is washed carefully, it will be found to have tiny 

 particles of soil still clinging to it. Examined under the micro- 

 scope, these particles of soil seem to be cemented to the sticky 



.vacuole 



^ p ro toplasm. 



#^- beginning 

 of ct rootTiafr* 



L.eell wall 



^..vacuole 



nucleus, 



a root hair 



The growth of a root hair. What are 

 root hairs, according to this diagram? 



,-N/ater ..vacuole r tytoplasm- 

 ; -a'\r- rSoil ! -nucleus 





zmom 



u 



U^Xf^< 



plumule 



root hairs 



A corn root covered with root 

 hairs which go between the 

 particles of soil to get water 

 and dissolved mineral matter. 



