the help of a
microscope. And when we get into the land of magnification, where the
little looks big and the slow looks quick, we see such evidence of
movement that we wonder not to hear as well as see the stream of life
that flows before our eyes.

In speaking of the cells of which plants are built, Huxley said that a
plant is "an animal enclosed in a wooden box." It is this prisoner, the
living protoplasm, that we may watch pacing round its prison walls. And
we may see it stop as though frightened at our rough usage, and then,
after a hesitating twitch or two, we see it recover and once more flow
round the cell. Or we can watch under the microscope minute
free-swimming plants rushing across the field of view, all one way, like
a flock of little green sheep that we can drive to and fro with a ray of
light for a sheep-dog.

But I am not going to deal with microscopic matters, but rather with
things on a bigger scale which can be seen with the naked eye. I will
begin by trying to show that very obvious movements are to be seen in
every kitchen garden, or in every garret window, where a scarlet runner
is grown for its red flowers' sake.

In a scarlet runner the shoot is not completely vertical, but bends over
to one side. To record the movements of the plant a series of
photographs may be taken vertically from above the plant, so that the end
of the shoot shows like the hand of a watch against a sort of clock-face
on which the points of the compass are marked. Such photographs show how
the shoot swings round in its instinctive search for another stick to
climb.

This well-known movement is performed by a co-ordinated series of
curvatures, the exact nature of which need not trouble us now. Let us
rather consider the less obvious power of co-ordination which enables a
plant to grow upwards in a straight line. Think of a forest of pine
trees, hundreds of thousands of them, all growing vertically up towards
the sky. Here is a clear case of movement, for the leading shoots were
once but a few inches from the ground, and now they are crawling along
vertical lines 100 feet up in the air. It may be said that this is mere
increase in size, not movement in the ordinary sense. But it may be made
plain that the trees could not grow in this way had they not a power of
curvature, to which the term _movement_ cannot be refused.

As it is not easy to experiment on pine trees we may use a pot of mustard
seedlings, which