ROOTS AND THE SOIL. 1 25 



ducting part ; and, as the cortex cells are cut off by this 

 from food, they wither and die away. But, long before 

 this period, some of these pericycle cells have begun to 

 produce new or branch-roots. It will be observed that 

 the pericycle is, from its position near phloem and xylem, 

 well nourished, and well supplied with water. One of 

 the pericycle cells, generally one opposite a xylem ray, 

 begins to divide and soon forms a bulging mass of cells, 

 which grows outwards, or eats through the cortex, until 

 it eventually reaches the outside, where it forms a new 

 rootlet absorbing on its own account. Roots, with 

 very few exceptions, arise in this way from the inside 

 of the older roots. Obviously this is of advantage, 

 as the water vessels, or xylem of the offspring, are 

 in direct connection with the xylem system of the 

 parent root. It is clear, therefore, that every detail in 

 the anatomy of the root is exactly what it should 

 be, if the working of it is conducted in the manner 

 described above. 



On the tip of the root there is usually a small cap of 

 dead material, often slimy on the outside. This thimble- 

 like rootcap protects the young cells underneath. It is 

 perpetually renewed by the epidermis cells underneath, 

 and this is necessary, as the rootcap must always be 

 injured and destroyed in its passage through the soil. 

 Some roots exploit the soil solely by means of their 

 system of growing and branching roots covered with 

 root hairs. But a great many, probably the majority, 

 are assisted by certain fungi, which may be regarded as 

 the servants or assistants to the root. The roots of 

 common trees, such as the oak, beech, and hazel, are 

 often clothed with a close-set mantle composed of the 

 threads of these fungi. This viycorhiza varies in colour 

 from white to pink, golden yellow, or rusty-brown. 



