BOOT STRUCTURE 



65 



germinate radish or other seed, so that no delicate 

 parts of the root will be injured. For this purpose, place 

 a few seeds in packing -moss or in the folds of cloth or 



blotting paper, being careful to 

 keep them moist. In a few days 

 the seed has germinated, and the 

 root has grown an inch or two 

 long. Notice that, excepting at a 

 distance of about a quarter of 

 an inch behind the tip, the root 

 is covered with minute hairs 

 (Figs. 11, 104). They are actu- 

 ally hairs, that is, root -hairs. 

 Touch them and they collapse, they are 

 so delicate. Dip one of the plants in 

 water, and when removed the hairs are 

 not to be seen. The water mats them 

 together along the root and they are no 

 longer evident. Eoot-hairs usually are 

 destroyed when a plant is pulled out of 

 the soil, be it done ever so carefully. 

 They cling to the minute particles of 

 soil. Under a microscope, observe how 

 they are flattened when they come in contact with grains 

 of sand (Chapter II). These root-hairs clothe the young 

 rootlets, and a great amount of soil is thus brought into 

 actual contact with the plant. Root-hairs are not young 

 roots : they soon die. 



138. The rootlet and the root -hair differ. The rootlet 

 is a solid, compact structure. The root -hair is a delicate 

 tube (Fig. W5), within the cell -wall of which is contained 

 living matter (protoplasm) ; and the lining membrane of 

 this wall permits water and substances in solution to pass 

 in. Being long and tube -like, these root -hairs are espe- 

 cially adapted for taking in the largest quantity of solu- 



104. Root of pumpkin 

 seedling, showing the 

 covering of root-hairs. 



