You remember moss first made seeds, and then used the seeds to grow spores, to grow new plants. The fern turns right around. It grows spores first. Then it uses the spores to grow seeds to grow plants. You can watch it do this if you have a great deal of patience, and a good magnifying glass. Take a bit of fern leaf and lay it on a pot full of soft, rich earth. Keep the earth moist and in a dim light. As the fern leaf decays and the spore cases burst, you may see the little scattered spores swell. They are soaking up water. One of them is sure to crack open and show a little white tip. That is a plant cell. Like the yeast cell it has a thin skin, and it is filled with jelly protoplasm. One cell grows out of another, like a honey comb. The cells spread and spread, until a heart-shaped leaf is formed.
The leaf lies on the ground, and it acts exactly like the leaf of a liver-wort. The upper side turns green, while from the lower side little hair-like suckers go down. Then little dots lift up their heads. These are cups and bottles just as on the liver-wort and mosses, too. In one kind of cup is a ball or egg, and in the other kind is the whip lash. The egg is called an ovule. It takes an ovule a certain time to become ripe, just as the egg in a chicken takes time to make a yolk and a white and to put a shell around it. The whips seem to know when the ovules are ripe, for they thrash around in the water in their cups, and finally flash across into the ovule cups. They cling together with a gelatin on the ovule, and grow together into——seed!
The fern seed use that heart-shaped leaf grown on the ground by the spore for food, and begin to grow right away. They sprout just like all true seeds, sending cells down for roots and up for leaves. The crown of the root is the buried stem of the plant. In the leaf stems the cell walls lengthen and stiffen into woody fibres. In some way that no one understands, the air and water pipes of the plants learn also to do the work of bones strong enough to support long feathery leaves. Besides, the fern is the first plant that grew from seeds. The mosses make seeds and then go back to spores to make new plants, but the ferns make spores first, and then seeds to grow plants. After the ferns, plants had no further use for spores. Having learned how to make seeds they all make them directly. Seeds are embryo, or unborn baby plants. The fern took two steps forward. It made leg and arm bones, and it made seed babies. (See Ferns, Filicales, Seeds.)
