THE WORK OF ROOTS 81 



covered over with layers of wood, other root hairs form in 

 profusion on the still newer portions which are of course 

 located in other feeding grounds. 



EXERCISE 26 



Object. — To study the origin of root hairs and anchor- 

 age roots. 



Procedure. — With the aid of a blunt knife or paddle, 

 remove with some of the soil surrounding it a young radish 

 seedling which has been growing in the sand for several 

 days. Note how the soil clings to the roots. Carefully 

 wash the clinging particles away. Examine the roots at 

 once with a hand lens, or better still, with a microscope. 

 See if you can find where a single cell in the surface of the 

 root has elongated into a root hair as shown in Figure 26. 



Split a parsnip or carrot lengthwise and see how the 

 anchorage roots originate or grow out from the stringy 

 central portion, the central cylinder, of the parent root. 

 If any other root is split in the same way at the point 

 where the anchorage root joins the parent root, its union 

 with the central cylinder of the larger root may be as 

 easily seen. 



Conclusion. — Which roots will be more easily torn 

 away when a plant is transplanted, • — the absorbing or 

 the anchorage roots? Why? Which class absorbs 

 moisture and mineral plant food ? Leaves throw off large 

 quantities of water when in direct sunlight. Why do we 

 shade a cabbage, toniato, or other young plant when it is 

 first set out ? How long is the shade necessary ? Why do 

 we often remove, or cut away, the twigs or leaves of a 

 tree or shrub when transplanting it ? 



68. How Roots work their Way through the Soil. — 

 A young root must work its way through the soil, avoiding 



