326 



ELEMENTS OF GENERAL SCIENCE 



under a tree a cubic centimeter of soil that does not contain 



rootlets. It is these small rootlets that bear the root hairs. 



It must not be supposed that root hairs are roots. The 



hairs never become 

 roots ; on the contrary, 

 as the root tip grows 

 out farther the old 

 root hairs die and new 

 ones are formed on 

 the newer parts of the 

 rootlet. 



327. Water-carrying 

 tissues. We have al- 

 ready spoken of the 

 way in which water 

 passes from cell to cell 

 in the tip of the root- 

 let and of the way in 

 which it is transferred 

 from the surface to the 

 interior of the root. In 

 some of the smaller 

 plants, such as the 

 mosses, water passes 

 through the plant di- 

 rectly, but in all the 

 FIG. 160. Transplanting a large tree 



Note how the soil and roots are protected so 

 that when the tree is planted, its roots will be 

 able readily to gain anchorage and supply the 

 rest of the tree with soil water. Photograph 

 by American Forestry 



larger plants there is 

 a more intricate system 

 by means of which it is 

 carried. The structure 

 of the water-carrying 

 parts is so similar in roots and stems that we shall use a stem 

 for our example. If we cut a stem with leaves from any of 

 our common trees and stand it with the end in red ink for 

 a while, we shall find that the ink has ascended the stem as 



