THE ROOT 



229 



the side-roots will often be found just beneath the periphery of 

 their crowns. In the same measure as the crown of the tree 

 increases iio, width, its roots grow to have the full benefit of the 

 water falling from the leaves. 



(c) Root-hairs — Allow some seeds of maize or mustard to 

 germinate between sheets of moist blotting paper. Put each 

 plant into a phial filled with water fixing its stem in the neck of 

 the phial with a cotton stopper. Examine the roots and you 



1. 2. 3. 



lU 



Fig. 21]. — 1. Root-hairs of the Mustard 

 seedling. 2. The same with particles of soil 

 clinging to the root-hairs. 3. Root-hairs 

 {H, 200 times enlarged), which are mere 

 outward prolongations of the cells forming 

 the epidermis (E). 



will find a delicate down just a little above the end of each tap- 

 root and of each side-root. This down consists of numerous little 

 hairs or threads. When a seedling is carefully taken out of the 

 soil, the root-hairs cannot be distinctly seen as they are too thickly 

 covered with earth (see fig. 211, 2). Even if washed in water, 

 the root-hairs cannot be freed from the particles of earth. So 

 closely do they cling to them, — you would sooner break off the 



