68 Principles of Plant Culture. 
B hy growth, scarcely ex- 
Ait} ceeded half an inch 
zi long. In Fig. 26, the 
\ parts that are increas- 
ing in length are con- 
» e siderably shorter than 
the root-tips, (R. T.) to 
which no sand adheres. 
ee 
-, 
f 101. The Root- 
“Ve Hairs (Fig. 27 B.) de- 
velop just behind the 
elongating part of the 
1( adh rootlet, and are present 
Ns jf &, in nearly all plants. 
j es Their object is to ab- 
4 LE ms | sorb water, with the 
ar: y A food materials it con- 
2 % B Bon. tains. The root-hairs 
a : 8 Bs \\ greatly increase the ab- 
Poa ‘\ ae sorbing surface of the 
“ S ei _ roots, just as leaves in- 
. 3) & “~ crease the absorbing 
wy  F PRES BRisurface of the plant 
oe ef above ground. Hach 
a RH ee root-hair consists of a 
ra x single elongated cell 
a VRY ig. 28), and in com- 
a mon with the cells in 
IR other living parts of 
Fic. 26. Roots of young wheat plant. The parts the plant, is filled with 
inclosed in sand (R H.) are surrounded by root- protoplasm (13). As 
hairs. R. T. root-tips; e, older parts of root. Na- : 
tural size. (After Frank and Tschirch) the extremity of the 
