THE PARTS OF THE SEEDLING. 13 
* 
ing glass, then as opaque objects in a cell under a low power 
of the miscroscope; finally cut off a very small portion of the 
root with its hairs and examine in water with a power of 150 
to 200 diameters.? 
Make several sketches of the root-hairs and compare with 
Figs. 5and 19. Notice that they do not cover all portions 
1a 
a 
fa 
| 
5 
YL 
Ss 
Fic. 3.— Lengthwise Section through Tip of a Root of Barley. (Much magnified.) 
a, thick outer wall of epidermis; 6 (portion bounded by the heavy line), the central 
cylinder of the root; c, the growing-point, from which the root-cap is produced 
(in this and similar plants) and from which growth in length proceeds ; d, loose 
cells of the root-cap. 
of the rootlets. Where are they most abundant? Observe 
that each hair is in reality a very slender tube, closed at the 
ends, and with walls of extreme thinness. 
The root-hairs in plants growing under ordinary conditions 
_1Great care is needed to prevent the root-hairs from becoming distorted by 
pressure, and they shrivel up in dry air almost at once. 
