We have now seen how a plant springs up, feeds itself, grows,
stores up food, withers, and dies; but we have said nothing yet
about its beautiful flowers or how it forms its seeds. If we
look down close to the bottom of the leaves in a primrose root
in spring-time, we shall always find three or four little green
buds nestling in among the leaves, and day by day we may see the
stalk of these buds lengthening till they reach up into the open
sunshine, and then the flower opens and shows its beautiful pale-
yellow crown.
We all know that seeds are formed in the flower, and that the
seeds are necessary to grow into new plants. But do we know the
history of how they are formed, or what is the use of the
different parts of the bud? Let us examine them all, and then I
think you will agree with me that this is not the least wonderful
part of the plant.
Remember that the seed is the one important thing and then notice
how the flower protects it. First, look at the outside green
covering, which we call the calyx. See how closely it fits in
the bud, so that no insects can creep in to gnaw the flower, nor
any harm come to it from cold or blight. Then, when the calyx
opens, notice that the yellow leaves which form the crown or
corolla, are each alternate with one of the calyx leaves, so that
anything which got past the first covering would be stopped by
the second. Lastly, when the delicate corolla has opened out,
look at those curious yellow bags just at the top of the tube
(b,2, Fig. 43). What is their use?
But I fancy I see two or three little questioning faces which
seem to say, "I see no yellow bags at the top of the tube." Well,
I cannot tell whether you can or not in the specimen you have in
your hand; for one of the most curious things about primrose
flowers is, that some of them have these yellow bags at the top of
the tube and some of them hidden down right in the middle. But
this I can tell you:those of you who have got no yellow bags at
the top will have a round knob there (I a, Fig. 43), and will find
the yellow bags (b) buried in the tube. Those, on the other hand,
who have the yellow bags (2 b, Fig. 43) at the top will find the
knob (a) half-way down the tube.
Now for the use of these yellow bags, which are called the
anthers of the stamens, the stalk on which they grow being
called the filament or thread. If you can manage to split them
open you will find that they have a yellow powder in them,
called pollen, the same as the powder which sticks to your nose
when you put it into a lily; and if you look with a magnifying
glass at the little green knob in the centre of the flower, you
will probably see some of this yellow dust sticking on it (A,
Fig. 43). We will leave it there for a time, and examine the
body called the pistil, to which the knob belongs. Pull off the
yellow corolla (which will come off quite easily), and turn back
the green leaves. You will then see that the knob stands on the
top of a column, and at the bottom of this column there is a
round ball (s v), which is a vessel for holding the seeds. In
this diagram (A, Fig. 43) I have drawn the whole of this curious
ball and column as if cut in half, so that we may see what is in
it. In the middle of the ball, in a cluster, there are a number of
round transparent little bodies, looking something like round
green orange-cells full of juice. They are really cells full of
protoplasm, with one little dark spot in each of them, which
by-and-by is to make our little plantlet that we found in the
seed.
"These, then, are seeds," you will say. Not yet; they are only
ovules, or little bodies which may become seeds. If they were
left as they are they would all wither and die. But those little
grains of pollen, which we saw sticking to the knob at the top,
are coming down to help them. As soon as these yellow grains
touch the sticky knob or stigma, as it is called, they throw out
tubes, which grow down the column until they reach the ovules. In
each one of these they find a tiny hole, and into this they
creep, and then they pour into the ovule all the protoplasm from
the pollen-grain which is sticking above, and this enables it to
grow into a real seed, with a tiny plantlet inside.
This is how the plant forms its seed to bring up new little ones
next year, while the leaves and the roots are at work preparing
the necessary food. Think sometimes when you walk in the woods,
how hard at work the little plants and big trees are, all around
you. You breathe in the nice fresh oxygen they have been
throwing out, and little think that it is they who are making
the country so fresh and pleasant, and that while they look as if
they were doing nothing but enjoying the bright sunshine, they
are really fulfilling their part in the world by the help of
this sunshine; earning their food from the ground working it up;
turning their leaves where they can best get light (and in this it
is chiefly the violet sun-waves that help them), growing, even at
night, by making new cells out of the food they have taken in the
day; storing up for the winter; putting out their flowers and
making their seeds, and all the while smiling so pleasantly in
quiet nooks and sunny dells that it makes us glad to see them.
But why should the primroses have such golden crowns? plain green
ones would protect the seed quite as well. Ah! now we come to a
secret well worth knowing. Look at the two primrose flowers, 1
and 2, Fig. 43, p. 163, and tell me how you think the dust gets
on to the top of the sticky knob or stigma. No. 2 seems easy
enough to explain, for it looks as if the pollen could fall down
easily from the stamens on to the knob, but it cannot fall up,
as it would have to do in No. 1. Now the curious truth is, as Mr.
Darwin has shown, that neither of these flowers can get the dust
easily for themselves, but of the two No. 1 has the least
difficulty.
Look at a withered primrose, and see how it holds its head down,
and after a little while the yellow crown falls off. It is just
about as it is falling that the anthers or bags of stamens burst
open, and then, in No. 1 (Fig. 44), they are dragged over the
knob and some of the grains stick there. But in the other form
of primrose, No. 2, when the flower falls off, the stamens do
not come near the knob, so it has no chance of getting any
pollen; and while the primrose is upright the tube is so narrow
that the dust does not easily fall. But, as I have said, neither
kind gets it very easily, nor is it good for them if they do. The
seeds are much stronger and better if the dust or pollen of one
flower is carried away and left on the knob or stigma of another
flower; and the only way this can be done is by insects flying
from one flower to another and carrying the dust on their legs and
bodies.
If you suck the end of the tube of the primrose flower you will
find it tastes sweet, because a drop of honey has been lying
there. When the insects go in to get this honey, they brush
themselves against the yellow dust-bags, and some of the dust
sticks to them, and then when they go to the next flower they
rub it off on to its sticky knob.
Look at No. 1 and No. 2 (Fig. 43) and you will see at once that
if an insect goes into No. 1 and the pollen sticks to him, when
he goes into No. 2 just that part of his body on which the
pollen is will touch the knob; and so the flowers become what we
call "crossed," that is, the pollen-dust of the one feeds the
ovule of the other. And just the same thing will happen if he
flies from No. 2 to No. 1. There the dust will be just in the
position to touch the knob which sticks out of the flower.
Therefore, we can see clearly that it is good for the primrose
that bees and other insects should come to it, and anything it
can do to entice them will be useful. Now, do you not think that
when an insect once knew that the pale-yellow crown showed where
honey was to be found, he would soon spy these crowns out as he
flew along? or if they were behind a hedge, and he could not see
them, would not the sweet scent tell him where to come and look
for them? And so we see that the pretty sweet-scented corolla is
not only delightful for us to look at and to smell, but it is
really very useful in helping the primrose to make strong
healthy seeds out of which the young plants are to grow next
year.
And now let us see what we have learnt. We began with a tiny
seed, though we did not then know how this seed had been made.
We saw the plantlet buried in it, and learnt how it fed at first
on prepared food, but soon began to make living matter for
itself out of gases taken from the water through the cells to
its stomach - the leaves! And how marvellously the sun-waves
entering there formed the little green granules, and then helped
them to make food and living protoplasm! At this point we might
have gone further, and studied how the fibres and all the
different vessels of the plant are formed, and a wondrous history
it would have been. But it was too long for one hour's lecture,
and you must read it for yourselves in books on botany. We had to
pass on to the flower, and learn the use of the covering leaves,
the gaily coloured crown attracting the insects, the dust-bags
holding the pollen, the little ovules each with the germ of a new
plantlet, lying hidden in the seed- vessel, waiting for the
pollen-grains to grow down to them. Lastly, when the pollen crept
in at the tiny opening we learnt that the ovule had now all it
wanted to grow into a perfect seed.
And so we came back to a primrose seed, the point from which we
started; and we have a history of our primrose from its birth to
the day when its leaves and flowers wither away and it dies down
for the winter.
But what fairies are they which have been at work here? First,
the busy little fairy Life in the active protoplasm; and
secondly, the sun-waves. We have seen that it was by the help of
the sunbeams that the green granules were made, and the water,
carbonic acid, and nitrogen worked up into the living plant. And
in doing this work the sun-waves were caught and their strength
used up, so that they could no longer quiver back into space. But
are they gone for ever? So long as the leaves or the stem or the
root of the plant remain they are gone, but when those are
destroyed we can get them back again. Take a handful of dry
withered plants and light them with a match, then as the leaves
burn and are turned back again to carbonic acid, nitrogen, and
water, our sunbeams come back again in the flame and heat.
And the life of the plant? What is it, and why is this protoplasm
always active and busy? I cannot tell you. Study as we may, the
life of the tiny plant is as much a mystery as your life and
mine. It came, like all things, from the bosom of the Great
Father, but we cannot tell how it came nor what it is. We can
see the active grains moving under the microscope, but we cannot
see the power that moves them. We only know it is a power given
to the plant, as to you and to me, to enable it to live its
life, and to do its useful work in the world.