THE ROOT. 



69 



Stele. Soon a growing point is formed (fig. 56). The rootlet 

 is thus in its early stage completely hidden, being buried 

 beneath the cortex, through which it gradually makes its way, 

 partly by disorganizing the tissues by pressure, and, probably, 



Fig. 56. Fig. 57 



Fig. 56. — Transverse section of a root of a fern {Ptetis cvetica), passing through a 

 rootlet which has not yet emerged Only the stele and three rows of cortex shown. 

 a, apical cell of rootlet, forming anteriorly the root-cap, ^/, and posteriorly the body 

 of the root, ec, e, c, pd\ A, wood strands; /, bast strand with its fellow opposite ; pe, 

 outer layer of stele; ?«, inner layer of cortex; p, cells partly disorganized and 

 digested ; d, cells of cortex, which will be disorganized as rootlet advanced. Highly 

 magnified — After Van Tieghem. 

 Fig. 57. — The same as fig. 56, but older ; not quite so much magnified. The rootlet 

 is just emerging from the parent root, pd, c, stele of the rootlet ; ec, its cortex ; d, 

 disorganized cells of cortex ec', of parent root ; d', secondary wood ; other letters as 

 in fig. 56.— After Van Tieghem. 



partly by actually digesting and absorbing the material of 

 these cells. When the rootlet reaches the surface it emerges, 

 therefore, from a distinct rift in the cortex (fig. 57). 



85. Buds. — New shoots may be formed by the roots, either 

 as a result of injuries, or normally. In a partially developed 

 form, these constitute buds (see Tj 91). Whether formed as 



