ABSORPTION BY ROOTS 167 
largely magnified in Figure 38. These root-hairs, 
which cluster about the 
growing point of the 
young roots, are the 
organs of the plant 
that absorb soil-water. 
They are of value only 
for limited periods of 
time, for as they grow 
older, they lose their 
power of water absorp- 
tion. In fact, they are 
active only when they 
are in actual process 
of growth. It follows, 
therefore, that water 
absorption occurs near 
the tips of the growing 
roots, and whenever a 
plant ceases to grow 
the water absorption 
ceases also. The root- 
hairs are filled with a 
dilute solution of vari- 
ous substances, as yet 
poorly understood, 
| 
\\ 
a 
Rasy 
Fig. 38. } Wheat root, showing 
which plays an impor- soil particles clinging to the lower part 
tant part in the ab- where the root-hairs are active. 
sorption of water and plant-food from the soil. 
