ROOTS 49 
mainly through the root-hairs. These are delicate, hair- 
like outgrowths from the epidermis of -the root. They 
are, as seen in Fig. 11, thin-walled tubes, of nearly uniform 
diameter, closed at the outer end and opening at the inner 
end into the epidermis-cell from which they 
spring. The relation of each hair to the 
epidermis-cell is still better shown in Fig. 
23, which represents a very young root- 
hair and a considerably older one. 
61. Absorption of Water by Roots. — 
Many experiments on the 
cultivation of corn, wheat, omg 
oats, beans, peas, and other Led ‘ ress 
familiar plants in water have 
proved that some plants, at 
any rate, can thrive very 
well on ordinary lake, river, 
or well water, together with 
the food which they absorb 
from the air (Chapter XII). 
Just how much water some 
kinds of plants give off (and 
therefore absorb) per day Geek 
will be discussed when the 4,a very young root-hair; B,a much 
older one (both greatly magnified). 
uses of the leaf are studied. e, cells of the epidermis of the root ; 
is m, nucleus; s, watery cell-sap; p 
Fr or the present it 1s suffi- thicker protoplasm, lining the cell- 
cient to state that even an wall. 
annual plant during its lifetime absorbs through the roots 
very many times its own weight of water. Grasses have been 
known to take in their weight of water in every twenty- 
four hours of warm, dry weather. This absorption takes 
