THE SOIL AND THE PLANT 



loosen as few roots as possible. How do the roots compare in area 

 with the part above the ground? Try to trace a single root of the 

 corn plant from the stalk to its very tip. How long are the roots of 

 mature plants ? Are they deep or shallow feeders ? Germinate some 

 oats or beans in a moist chamber as suggested and observe the root 

 hairs. 



SECTION IX HOW A PLANT FEEDS FROM THE SOIL 



Plants receive their nourishment from two sources, from 

 the air and from the soil. The soil food, or mineral food, 

 must, dissolved in water, reach the plant through the root 

 hairs, with which all plants are provided in great numbers. 

 Each of these hairs may be compared 

 to a finger reaching among the par- 

 ticles of earth for food and water. 

 If we examine the root hairs ever so 

 closely, we find no holes, or pores, 

 in them. It is evident that no solid 

 particles can enter the root hairs. 

 All food must then pass into the 

 root in solution. 



An experiment just here will help 

 us to understand how a root feeds. 

 Secure a narrow glass tube like the 

 one in Fig. 22. If you cannot get 

 a tube, a narrow, straight lamp chim- 

 ney will, with a little care, do nearly 

 as well. Cut from a bladder made soft by soaking, a piece 

 large enough to cover the end of the tube or chimney and 

 to hang over a little all around. Make the piece of blad- 

 der secure to the end of the tube by wrapping tightly 

 with a waxed thread, as at B. Partly fill the tube with 



FIG. 22. EXPERIMENT 

 TO SHOW HOW ROOTS 

 TAKE UP FOOD 



