96 



30TANY. 



has been applied (Fig. 81). These are composed of single 

 cells, which have very thin and delicate walls (Fig. 82), and 

 are the active agents in the absorption of nutritive matters 

 for the plant. 



Fig. 82. Root-hairs of a seedling rye plant. A, the ends of three hairs, one much 

 smaller than the others ; the larger ones have particles of sand adhering to and im- 

 bedded in their walls ; B, the base of a hair growing from the rooi-cell, r. X 900. 



129. In the development of the hairs on aerial parts of 

 plants it frequently happens that the terminal cell becomes 

 changed into a secreting cell, in which gummy, resinous, or 

 other substances are produced ; sometimes several terminal 



