But we are not yet nearly at an end of the contrivances of flowers to secure the visits of insects. Have you not observed that different flowers open and close at different times } The daisy receives its name day's eyey because it opens at sunrise and closes at sunset, while the evening primrose {CEnothera biennis) and the night campion {^Silene noctijiora) spread out their flowers just as the daisy is going to bed.

What do you think is the reason of tliis ? If you go near a bed of evening primroses just when the sun is setting, you will soon be able to guess, for they will then give out such a sweet scent that you will not doubt for a moment that they are calling the evening moths to come and visit them. The daisy opens by day, because it is visited by day insects, but those particular moths which can carry the pollen- dust of the evening primrose, fly only by night, and if this flower opened by day other insects might steal its honey, while they would not be the ri^lit size or shape to touch its pollen-bags and carry the dust.

It is the same if you pass by a hon ysuckle in the evening ; you will be surprised how much stronger its scent is than in the day-time. This is because the sphinx hawk-moth is the favourite visitor of that flower, and comes at nightfall, guided by the strong scent, to suck out the honey with its long proboscis, and carry the pollen-dust.

Again, some flowers close whenever rain is coming. The pimpernel {Anagallis arvensis) is one of these, hence its name of the '* Shepherd's Weather-glass." This little flower closes, no doubt, to prevent its pollen-dust being washed away, for it has no honey ; while other flowers do it to protect the drop of honey at the bottom of their corolla. Look at the daisies for example when a storm is coming on ; as the sky grows dark and heavy, you will see them shrink up and close till the sun shines again. They do tliis because in each of the little yellow florets in the centre of the flower there is a drop of honey which would be quite spoiled if it were washed by the rain.

And now you will see why cup-shaped flowers so often droop their heads—think of the harebell, the

snowdrop, the li!y-of-the-valley, the campanula, and a host of others ; how pretty they look with their bells hanging so modestly from the slender stalk ! They are bending down to protect the honey-glands within them, for if the cup became full of rain or dew the honey would be useless, and the insects would cease to visit them.

But it is not only necessary that the flowers should keep their honey for the insects, they also have to take care and keep it for the right kind of insect Ants are in many cases great enemies to them, for they like honey as much as bees and butterflies do^ yet you will easily see that they are so sniall that if they creep into a flower they pass the anthers without rubbing against them, and so take the honey without doing any good to the plant Therefore we find numberless contrivances for keeping the ants and other creeping insects away. Look for example at the hairy stalk of the primrose flower ; those little hairs are like a forest to a tiny ant, and they protect the flower from his visits. The Spanish catchfly {Silene otites), on the other hand, has a smooth, but very gummy stem, and on this the insects stick, if they try to climb. Slugs and snails too will often attack and bite flowers, unless they are kept away by thorns and bristles, such as we find on the teazel and the burdock. And so we are gradually learning that everything which a plant does has its meaning, if we can only find it out, and that even every insignificant hair has its own proper use, and when we are once aware of this a flower-garden may become quite a new world to us if we open our eyes to all that is going on in it.

But as we cannot wander among many plants today, let us take a few which the bees visit, and see how they contrive not to give up their honey without getting help in return. We will start with the blue wood-geranium, because from it we first began to learn the use of insects to flowers.

More than a hundred years ago a young German botanist, Christian Conrad Sprengel, noticed some soft hairs growing in the centre of this flower, just round the stamens, and he was so sure that every part of a plant is useful, that he set himself to find out what these hairs meant. He soon discovered that they protected some small honey-bags at the base of the stamens, and kept the rain from washing the honey away, just as our eyebrows prevent the perspiration on our faces from running into our eyes. This led him to notice that plants take great care to keep their honey for insects, and by degrees he proved that they did this in order to tempt the insects to visit them and carry off their pollen.

The first thing to notice in this little geranium flower is that the purple lines which ornament it all point directly to the place where the honey lies at the bottom of the stamens, and actually serve to lead tlie bee to the honey ; and this is true of the veins and marking of nearly all flowers except of those which open by night, and in these they would be useless for the insects would not see them.

When the geranium first opens, all its ten stamens are lying flat on the corolla or coloured crown, as in the left-hand flower in Fig. 58, and then the bee cannot get at the honey. But in a Fig. 58. short time five stamens begin to raise themselves and cling round the stigma or knob at the top of the seed-vessel, as in the middle flower. Now you would think they would leave their dust there. But no ! the stigma is closed up so tight that the dust cannot get on to the sticky part. Now, however, the bee can Geranhim sylvaticum^ tte Wood Geranium. get at the honey- In the left-hand flower the stamens are glands on the out- all lying down. In the middle flower five side of the raised stamens clasp the stigma. In the rightstamens and as he hand flower the stigma is open after all ; the stamens have fallen. sucks it, his back touches the anthers or dust-bags, and he carries off" the pollen. Then, as soon as all their dust is gone, these five stamens fall down, and the other five spring up. Still, however, the stigma remains closed, and the pollen of these stamens, too, may be carried away

to another flower. At last these five also fall down, and then, and not till then, the stigma opens and lays out its five sticky points, as you may see in the righthand flower, Fig. 58.

But its own pollen is all gone, how then will it get any ? It will get it from some bee who has just taken it from another and younger flower ; and thus you see the blossom is prevented from using its own pollen, and made to use that of another blossom, so that its seeds may grow healthy and strong.

The garden nasturtium, into whose blossom we saw the humble-bee poking his head, takes still more care of its pollen-dust. It hides its honey down at the end of its long spur, and only sends out one stamen at a time instead of five like the geranium ; and then, when all the stamens have had their turn, the sticky knob comes out last for pollen from another flower.

All this you may see for yourselves if you find geraniums* in the hedges, and nasturtiums in your garden. But even if you have not these, you may learn the history of another flower quite as curious, and which you can find in any field or lane even near London. The common dead-nettle (Fig. 59) takes a great deal of trouble in order that the bee may carry off its pollen. When you have found one of these plants, take a flower from the ring all round the stalk and tear it gently open, so that you can see down its throat. There, just at the very bottom, you will

The scarlet and other bright geraniums of our flower-gardens are not true geraniums, but pelargoniums. You may, however, watch all these peculiarities in them if you cannot procure the true wild geranium.

find a thick fringe of hairs (/, No. 2, Fig. 59), and you will guess at once that these are to protect a drop of honey below. Little insects which would

Fig. 59.

Flower of the Dead-Nettie {Lamium album), I, Whole. 2, Cut in half. /, Fringe of hairs protecting honey at base. J, Stigma, d!, Anthers of stamens. /, Lip of flower. creep into the flower and rob it of its honey without touching the anthers of the stamens Fig. 59) cannot get past these hairs, and so the drop is kept till the bee comes to fetch it.

Now look for the stamens : there are four of them {a a)y two long and two short, and they are quite

hidden under the hood which forms the top of the flower. How will the bee touch them? If you were to watch one, you would find that when the bee alights on the broad Hp /, and thrusts her head down the tube, she first of all knocks her back against the little forked tip s. This is the sticky stigma, and she leaves there any dust she has brought from another flower; then, as she must push far in to reach the honey, she rubs the top of her back against the anthers a a, and before she comes out again has carried away the yellow powder on her back, ready to give it to the next flower.

Do you remember how we noticed at the beginning of the lecture that a bee always likes to visit the same kind of plant in one journey ? You see now that this is very useful to the flowers. If the bee went from a dead-nettle to a geranium, the dust would be lost, for it would be of no use to any other plant but a dead-nettle. But since the bee likes to get the same kind of honey each journey, she goes to the same kind of flowers, and places the pollen-dust just where it is wanted.

There is another flower, called the Salvia, which belongs to the same family as our dead-nettle, and I think you will agree with me that its way of dusting the bee s back is most clever. The Salvia (Fig. 60) is shaped just like the dead-nettle, with a hood and a broad lip, but instead of four stamens it has only two, the other two being shrivelled up. The two that are left have a very strange shape, for the stalk or filament of the stamen (i/) is very short, while the anther, which is in most flowers two little bags stuck together, has here grown out into a long thread a b, with a little dust-bag at one end only. In i, Fig. 60, you only see one of these stems, because the flower is

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