24 THE OAK 



CHAPTER III 



THE SEEDLING AND 7OUNG PLANT 



BEFORE proceeding to describe the further growth and 

 development of the seedling, it will be well to examine 

 its structure in this comparatively simple stage, in 

 order to obtain points of view for our studies at a later 

 period. For many reasons it is advantageous to begin 

 with the root-system. If we cut a neat section accu- 

 rately transverse to the long axis of the root, and a few 

 millimetres behind its tip, the following parts may be 

 discerned with the aid of a good lens, or a microscope, 

 on the flat face of the almost colourless section. A cir- 

 cular area of greyish cells occupies the centre this is 

 called the axis cylinder of the young root (fig. 5, A, a). 

 Surrounding this is a wide margin of larger cells, forming 

 a sort of sheathing cylinder to this axial one, and termed 

 the root-cortex. The superficial layer of cells of this root- 

 cortex has been distinguished as a special tissue, like an 

 epidermis, and as it is the layer which alone produces 

 the root-hairs, we may conveniently regard it as worthy 

 of distinction as the piliferous layer (fig. 5, e). 



Similar thin sections a little nearer the tip of the 



