Abstract
Observing life in all its forms, we wonder as to its origin. We see animals and plants of all sorts, from one-celled individuals to very complex organisms containing billions of cells. Naturally we look for origins among the simpler, one-celled forms. Then we note that the animals feed on the plants, and that plants depend but incidentally upon the animals. This unbalanced relation at once suggests that the plants may have preceded the animals in evolution. But when we study the one-celled forms of both, we find ourselves confused, they are so much alike. It looks as though they originated together from a common beginning, and then diverged very early along two boldly distinct lines.