sprouts at the margins, and finally the main
root perishes, and two roots, with branches a little distance apart,
support each a cluster of stems above ground.

[Illustration: FIG. 2.--Small tree, "grub," of white oak many times
killed back; finally dead at the middle and sprouting on the margins.]

[Illustration: FIG. 3.--Grub, or remains of a white oak, doubtless
at one time much like Fig. 2, but now decayed in the middle, including
its main root; sprouting on the margins, farther and farther out after
the tops were killed, to the ground.]

[Illustration: FIG. 4.--Grub, or remains of a white oak, still older
than the one represented in Fig. 3. A hole appears where the tap root
has rotted away. The right-hand portion is already dividing, and in
time, if often killed back, we might find several distinct oaks as
descendants from one acorn.]

There can be no doubt that young oak trees slowly move in this manner
from one place to another. If in fifty years we have two distinct
grubs or branches, three or four feet apart, where the connecting
part has finally died out, I see no reason why in another fifty years
each one of the two may not again have spread and divided, giving
us at least four grubs, or clusters of sprouts, all originally coming
from one acorn; and so the matter might go on. This is slow traveling,
I admit, but there is nothing to hinder nature from taking all the
time she wants.

[Illustration: FIG. 5.--Part of a grub of white oak, still alive and
spreading over the ground, the central portions dying, the margins
alive and spreading.]

CHAPTER III.
PLANTS MULTIPLY BY MEANS OF STEMS.

7. Two grasses in fierce contention.--In growing a lawn at the
Michigan Agricultural College, a little Bermuda grass was scattered
with June grass, and the struggle has been most interesting. In the
spring and for six weeks in autumn, when moisture usually abounds
and the weather is cool, June grass thrives and little else is seen.
In the dry, hot weeks of July and August, June grass rests and the
Bermuda, which continues to spread, assumes control of the lawn, with
but little of the June grass in sight. Each struggles for possession
and does the best it can, and to some extent one supplements the other,
with the result that at all times from spring to fall there is a close
mat of living green which delights the eye and is pleasant to the
feet that tread upon it. In soft ground, with plenty of room, a bit
of q