At night time, when the sun's rays are not present, as the heat radiates quickly from the plants on the ground, each plant becomes thereby cooler than the earth and stones which surround it. This causes the watery particles which the air contains, to condense on its leaves and flowers, in the same manner as you see the moisture in the air of a crowded room, settle on the outside of a glass of cold water; and, what is most wonderful, the surface of each plant is so constructed as to allow the escape of just so much heat, and to receive just so much dew in return, as its peculiar nature requires. You may see, if you look, that some plants always have more dew on them than others.
On a cloudy night, when dews are not so much required, a great part of the heat thus radiated is sent back, being reflected by the clouds. Hence the dew falls less heavily at such a time than on a clear starlight night, when every blade of grass and every little flower sends out its ray of heat to an indefinite extent, and may possibly meet another ray from the Dog-stars or one of the Pleiades!
This is very wonderful; but if you think, you will perceive that it is not more wonderful than that a ray of light should travel so far. Every particle of the surface of these stars does its part in emitting light, and by that the light of our nights is increased; and if Light is affected by such remote influences, why should not Climate be so affected?
IX. As everything has a place to fill up amongst the creatures by which it becomes connected with the universal system, we find innumerable instances of things being most wonderfully provided with powers of retaining the position for which they were created, when circumstances may oppose it. The tendency which every animal has to preserve its own life, supplies abundant illustration. It is this which causes the Arctic animals to change their colour to white in winter, and the swallows to migrate to warmer regions. But there is something selfish in this, as the provision is merely to save the animal's own life. Much more beautiful is it to observe the operation of the affections of parent animals towards their offspring, by which the young, when they are incapable of taking care of themselves, are kept alive and preserved from injury often at the sacrifice of the enjoyment, and even of the life of their parent. You will remember what I told you respecting the love of the old whales towards the suckers. Nothing parts with its own life willingly, but in a great many animals it may be seen that there is a greater regard to the preservation of their race than of their own individual lives.
X. These tendencies may be seen in vegetables as well as in animals. The young buds of various plants, of the common poppy for example, hang down their heads, so that the bottom of the calyx, as it is called by botanists, is placed upwards, and forms a sort of thatch or roof. When the flower spreads out its bright broad leaves, although its weight is increased, yet it then boldly lifts up its head to the sun, and the neck of the stalk which seemed unable to bear up the bud, is well able to sustain the full flower. Now if it were otherwise, and if the bud held the same position as the flower, the rain would run into the calyx and would lie there, so as to cause the petals or leaves of the future flower to become rotten.
In this Kingdom of Nature, the unwillingness to part with life is even more wonderfully exhibited than in animals.
Seeds have been known to retain their principle of life for centuries, and long after they have seemed perfectly dead and dry, when placed in proper circumstances, they have sent out shoots and borne flowers and fruit. Mr. White relates, that when some old beech trees were removed from a spot in the neighbourhood of Selborne, where they must have stood for ages, some strawberry plants sprung up, of which the seeds must have lain dormant under the roots of the beeches. When the Spaniards took possession of Peru, many of the race of Incas, the rulers of that country, fled to the deserts and took with them what provisions they could carry. There are now, sometimes, found in these deserts, ancient vessels with very narrow mouths, containing at the bottom a few grains of maize or Indian corn, the remains of the stock of those poor exiles. I have got one of the vessels; and the maize which came out of it was sown, and took root and bore seed, though it must have been bottled up for considerably more than three centuries.
But now I am going to tell you something still more surprising than this. The Ancient Egyptians, from some notion connected with their religion, used at times to place in the hands and under the soles of the feet of the bodies they embalmed, the roots of a kind of lily. The roots are of a bulbous sort, not much unlike an onion, and they have often been found on those mummies which have been uncovered. One or two of them have been set to vegetate, and have actually borne flowers and seed, after having slumbered in a mummy coffin for considerably more than 2000 years!