14 BOTANY 
water and examine the different parts in detail. In 
addition, each student should have his own plant, which 
may be removed from the soil with a spade and washed 
under the tap. Such parts as are missing may be 
examined in the more carefully removed specimen. 
There is one main root ealled the tap-root, which goes 
down deep into the soil and tapers towards the tip. 
This throws off branches throughout its entire length, 
and these again produce secondary branches, which 
in their turn may branch repeatedly. By cutting 
through the main root just where a branch is given 
off it may be seen that the branch has burst through 
from the inside, having its origin in the interior tissues 
(Fig. 3). 
The older parts of the root are hard and woody, 
but as we approach the ends of the more slender 
branches we find the tissues soft and tender. The 
ageregate length of all the root branches is very great, 
and by measuring a few of these and counting the rest, 
this may be roughly calculated. 
The root system of a maize plant examined by the 
author in this way, showed, without root hairs, a total 
of about 350 yards, while it is stated on good authority 
that the root system of a Spanish vine reached an 
ageregate length of 15 miles, and that of this length 
the major part must have been produced at the rate 
of 1,000 feet per day. 
Now examine the ends of the more delicate root 
branches with a lens. These will be found to be 
covered almost to their tips with a* delicate fur of 
white root hairs. These hairs are the really active 
parts of the root which do the work of absorbing the 
soil-water with its dissolved minerals. It is only close 
to the root tips that these hairs are found. The extreme 
tip, however, is devoid of hairs, being covered by the 
root cap which protects the delicate growing point as 
