ROOT 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- 



t \ ally hairs, that is, root -hairs. 



I Touch them and they collapse, they are 



^ so delicate. Dip one of the plants in 



I \ water, and when removed the hairs are 



''\ not to be seen. The water mats them 



1 together along the root and they are no 



longer evident. Root-hairs usually are 



* destroyed when a plant is pulled out of 



t . — i^ the soil, be it done ever so carefully. 



'..'...ii'm"'" ■^ilnwi',','-''t'i'ie They cling to the minute particles of 

 covering of root-hairs. ^qW Under a microscopc, 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, connpact structure. The root -hair is a delicate 

 tube (Fig. 105), tvithin the cell- tv all of which is contained 

 living matter {protoplasm); the ivall and the lining mem- 

 brane permit water and substances in solution to pass 

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

 cially adapted for taking iu the largest quantity of solu- 



