ROOTS. 9 



incalculable number of rootlets grow from the radicles 

 as fine as hairs. 



a, fibrous root of grass ; 6, the same, downy from growing in 

 loose sand. 



The roots of trees and most other plants, when once 

 formed, do not lengthen, except at the tips, a fact 

 proved by Du Ham el and Mr. T. A. Knight, who tied 

 threads around roots, and found that the spaces between 

 the threads always measured, the same. In the orchis 

 group, Professor Lindley proved, by similar experi- 

 ments, that this does not hold. 



The great care which Providence has taken for the 

 preservation of the life of plants, is strikingly mani- 

 fested in the fact, that any part of a plant which is 

 furnished with pores, or, in other words, which can 

 form buds, leaves, or branches, may be made to shoot 

 out rootlets, by placing it in warm and moist earth. 

 It is on this principle that plants are propagated by 

 cuttings and layers. 



It is a singular property of roots, that they seem as 

 anxious to shun the light, as the leaves and young 



