Let us call them Secundus. Secundus had small yellow flowers, like the marsh plants it was descended from. But one day some of the seeds of Secundus blew into the edge of a wood where the soil was rich and the air damp. This just suited the Secundus seeds, and they grew into very thrifty plants indeed. They had so much sap and grew so luxuriantly that their petals were twice as large as was usual with Secundus petals. These fine showy flowers also possessed a great deal of nectar, they had so much sap. Of course the bees came to them, and they were well fertilized. They set many seeds. The next year these strong seeds were able to grow even when their neighbors were not, and the plants that came from these seeds also had large showy flowers. These stronger plants held their own, you may be sure, and at last there was more of them than of the small-flowered plants. It was well for them this was so, for there came several bad seasons when nothing was just right for these plants. It was cold and stormy, and only the very strongest lived through it. But _they_ managed to survive, and their flowers were large and showy. All the weaker plants with smaller flowers were killed out, and only these large-flowered ones remained. They were _very_ different from their ancestors the marsh plants, and we shall have to call them Tertius. One day some of the seeds of Tertius were blown into a new kind of soil; they sucked up the juices of this new soil, and lo! some of their flowers opened white instead of yellow. It so happened that the white-flowered plants were stronger than the others. The bees liked them, too; for, being so strong and full of sap, they made plenty of honey. So these white-flowered ones increased in numbers very greatly. At last only the white ones could be found; the yellow ones had gradually given way before them until no yellow ones were left. So we will call the white-flowered people Quartus. Quartus lived a long time, each year bearing seeds, the strongest and best of which grew up and bore flowers. One day some of Quartus’ seeds were blown into a hot, sandy place; this almost killed them, but some of them managed to grow.