30 STRUCTURE AND PHYSIOLOGY OF SEED PLANTS 



jar of water. The jar should be as thin and transparent as 

 possible, and it is well to get a flat-sided rather than a cylin- 

 drical one. Leave the jar of cuttings in a sunny, warm place. 

 B. As soon as roots have developed at the nodes, and reached 

 the length of three quarters of an inch or more, arrange a 

 microscope in a horizontal position (Pig. 1) and examine the 



Fig. 1. Microscope on ring stand 



tip and adjacent portion of one of the young roots with a 

 power of from twelve to twenty diameters. Note : 



(1) The root cap, of loosely attached cells. 



(2) The central cylinder. 



(3) The cortical portion, a tubular part inclosing the 

 solid central cylinder. 



(4) The root hairs, which cover some parts of the outer 

 layer of the cortical portion very thickly. Observe 

 particularly how far toward the tip of the root the 

 root hairs extend, and where the youngest ones 

 are found. 



