Did you know that the ash and maple seeds actually have screw propellers, like a ship, so that they can ride on the wind? Pettigrew's great work, "Design in Nature," makes this very plain, both in word and picture.
In what way does the wind help to produce the seed of grasses as well as carry and plant them? (Any encyclopædia or botany will tell you how plants are fertilized.)
How could a tempest that blew down a tree help its seeds to get a start? Wallace, in his "World of Life," says that on a full-grown oak or beech there may be 100,000 seeds that are thus given a better chance of life.
Speaking of "wind ploughs," what is the object of ploughing anyway? The article on preparing the seed bed in "The Country Life Reader" tells about what ploughing means to the soil and also:
Why good soil takes up more room than poor.
Why it is a good thing to plough deep, but a bad thing, if you don't do it just right.
And farther on there is a most inspiring poem about the history of the plough from the days of early Egypt to the present. It begins like this:
"From Egypt behind my oxen,
With their stately step and slow,
Northward and east and west I went,
To the desert and the snow;
Down through the centuries, one by one,
Turning the clod to the shower,
Till there's never a land beneath the sun
But has blossomed behind my power."The deserts have helped to make western China fertile. How did they do it? (Look at your geography map and remember that the prevailing winds of the world are westerly.)
You'll find many interesting things about the winds and the soil in Keffer's "Nature Studies on the Farm" and Shaler's "[Outlines of Earth's History]." Shaler's "Man and the Earth" says a single gale may blow away more soil from an unprotected field than could be made in a geological age, and an hour's rain may carry off more than would pass away in a thousand years if the land were in its natural state. He also tells what to do to prevent the best part of ploughed fields from being carried off by the wind.
Have you any idea how far seed may be carried by a hurricane? Wallace, in his "Darwinism" deals with this question, and it's very important in the story of the earth. Beal's admirably written and illustrated little book on "[Seed Dispersal]." tells a world of interesting things about the wind as a sower. For instance:
How pigweed seeds are built so that wind can help them toboggan on snow or float on water;
How wind and water work together in the distribution of seeds;
About seeds that ride in an ice-boat;
About the monoplane of the basswood;
About the "flail" of the buttonwood, and how the wind helps it to whip out the seeds; and how the seeds then open their parachutes.
Dandelions go through quite a remarkable process in preparing for flight. I wonder if you have ever noticed it. Before the seeds get ripe Mother Dandelion blankets them at night and puts a rain-cloak on them on rainy days, and just won't let them get out, as shown on page 51. And do you know how she opens the flowers for the bees on sunshiny days?
There is no island, no matter how remote, that isn't supplied with insects. How do you suppose they get there? You may be sure the wind has something to do with it or I wouldn't mention the subject at the end of this chapter. (Wallace: "Darwinism.")
THE WEST WINDS AND THE RAINS
On the western slopes of this mountain the trees, with the help of the winds and the rain, climb to the very summit, while the other side of the mountain remains only a barren rock. The moisture-laden winds from the west glide up the slope, the air expands as it rises, the expansion cools it and down comes the rain! But the eastern slope gets little or none of it.
CHAPTER IV
(APRIL)