18 BOTANY. 



Synopsis. The root hairs are formed near the growing end of the young 

 root. 



The root hair is a single plant cell, very long and narrow. 

 The root hair is formed by the elongation of one of the outer cells of the 

 root. 



Cell wall, the enclosing cellulose membrane to protect and hold 



the cell contents. 

 Protoplasm. 

 Nucleus. 



The root- 

 hair cell. 



Granular protoplasm, arranged differently from that in spiro- 

 gyra ; a wall layer, and then stout strands and masses 



which reach across with clear rounded spaces between (the 

 vacuoles). 



Cell sap, in the vacuoles. 

 L Chlorophyll absent. 



Reactions of the protoplasm ; is killed, and stained yellowish brown with 

 iodine; a 1% aqueous solution of eosin does not stain it; it does stain with the 

 eosin when first killed with alcohol. 



Materials. Young seedlings of radish, corn, squash, or other plants, with 

 clean root hairs, grown in a germinator (see Demonstration 2). 

 A solution of iodine. 

 A 1% aqueous solution of eosin. 

 95$ alcohol (commercial strength). 



Watch glasses to receive small quantities of these solutions when the pupils 

 are engaged in exercise 10. Medicine droppers. 



For the demonstrations : Microscope, razor, glass slips, cover-glass circles, 

 dissecting needles. (Hereafter the microscope and accessories will not be 

 listed in each case for the demonstrations ; microscope, etc. , will be inserted 

 instead.) 



