Once upon a time there lived a little plant in a marshy place. We will call it Primus, not because that was the very first form of the plant, for it was not, but because that was its form when we first saw it. It had five small yellow petals, five small stamens, and an ovary. When its seeds were ripe, along came a great wind and blew them away from the marsh upon the dry land at the edge. Poor little seeds, they were out of their familiar wet marsh and they could not grow. But they did their best. Some of them managed to sprout, but soon they found the earth too dry and the sun too hot; so they said, “We will turn to other work; we will help the other plants and not try to grow ourselves.” So they changed into gases and minerals and other substances. But a few of the seeds continued to grow. They blossomed and bore seeds, but they were not just like the plants in the marsh. Mother Nature had helped them get a tougher skin and taught them how to shut tightly their pores in dry weather, so that the water within them could not escape. You see, they were already different from their parents, though you might not have noticed it if you had seen them, the difference was so slight. The seeds of these new plants sprouted the next season. They did not have a hard time to grow. They knew just what to do, and the best and strongest of them grew a few hairs to help cover up the pores, so the water would not go out too fast. It happened to be a very hot, dry season, and all the plants but these hairy ones stopped growing. They changed into gases and minerals and other substances to help the other plants. The hairy people got through the dry season very well. They set a good many seeds, and these seeds sprouted. The new plants remembered about the hairs and had plenty of them. Some were covered all over with a soft down. And it was well they were, for it was a _very_ hot, dry season, and all but the downy ones stopped growing and changed into minerals and gases and other substances to help the others. The seeds of the downy plants blew far over the dry land, far away from the marsh; but they had learned to live in the dry soil, and if you had found these downy people, you would hardly have known they were descended from the smooth, juicy, large-leaved marsh plants. Their stems were hard and tough and their leaves stiff and small. We can no longer call them Primus, they are so changed.