THE ROOT 67 
ARRANGEMENT OF TISSUES. 
To consider the path taken by the absorbed liquid 
from the root hairs to the stem for transmission to 
the leaves, we must now examine the arrangement of 
the tissues of the root. If we cut across the root of 
a young bean plant somewhat beyond the seedling 
stage we shall see that in the middle is a harder denser 
portion which forms the stele or vascular cylinder. 
Outside this is a ring of softer tissue, the cortex, and 
the whole is enclosed in a thin skin, the epidermis. The 
latter, however, is not so easy to peel off as in the stem. 
Now, with a wet razor, cut a number of very thin 
sections or slices (Fig. 45) from the severed end of the 
root (which must also be kept wet) and place them 
on a small piece of glass, moistening them with water 
to prevent their drying up. When held against a good 
light and examined with a hand lens, the essential 
points of tissue arrangement and structure may be seen. 
If the first sections are not satisfactory cut others, 
remembering always to keep razor and root as wet as 
possible. The tissues will appear to be perforated by 
numberless little openings separated from each other 
by very thin dividing walls. These are in most eases 
the cells which contain the living and active materials 
of the plant. They are really little closed boxes, 
generally with very thin walls, which have been sliced 
through by the razor. These will be seen to vary in 
size and appearance in the different layers of the root. 
In other words, in passing in from the epidermis to 
the centre of the stele, different tissues will be observed, 
a tissue being regarded as one kind of living material, 
doing work more or less peculiar to itself. 
The epidermis is chiefly protective, but just behind 
the growing points of all roots and root branches the 
cells of the epidermis lengthen outwards to form the 
all-important root hairs by which the absorbing surface 
is enormously increased. 
