THE LIFE AND GROWTH OF SEEDLINGS 



dll split even a mass of rock. It is well known that roots help 

 >nsiderably in breaking up the subsoil ; they also follow the 

 -ack of earthworms, which, as it were, prepare a passage for the 

 'oung plant. 



REGIONS OF THE ROOT. As a root grows, certain regions 

 may be detected : (i.) The growing-point is just behind the root- 

 cap. 



(ii.) Next comes the elongating region, that is the part growing 

 rapidly in length. 



(iii.) Behind that is the region bearing root-hairs. 

 (iv.) Behind that again, the region which is growing in thickness 

 id developing branches, i.e. lateral roots. 



In order to see how the branches arise, the outer tissues nearest 

 te branch should be scraped away, and it will then be seen that 

 ie branches arise internally ; or sections may be made and 

 :amined under the microscope. 



A transverse section should be made through the main root, 

 iust where one of the branches is 

 :oming off. In the accompanying 

 igure the branch (L) is seen arising 

 :om the inner tissues from one of 

 ie bundles of the wood. It then 

 mshes its way through the outer 

 issues, and grows out laterally from 

 ie main root. Although these 

 lateral roots grow more or less 

 horizontally, their tips bend down- 

 wards. This enables the root to 

 reach those portions of the soil 



where nutriment an pi moisture are most abundant. These 

 lateral roots are of special importance in trees. Both the 

 birch and the beech are able to thrive in very shallow soil, 

 on account of their immense system of lateral roots. Even 

 where trees have a deep root-system, their lateral roots are 

 of great use to them, for they usually extend horizontally to 

 the circumference of the tree. Every one knows that it is possible 

 to shelter under a tree during a slight shower, for until the foliage 



FIG. 9. Transverse section through 

 a dicotyledonous root. L, lateral 

 root. 



VOL. III. 2 



