XV. Water Babies and Other Babies that Drink Milk
As we have seen all the way through—and will see a great deal more, the more we look carefully at the picture in Nature's wonder book, the higher forms of life keep summing up the lives below, and foretelling higher lives to come.
The earthworm, with his joint-ringed body, foretells the crawfish, with his jointed shell; the crawfish foretells the fish, with his tail set the other way, and the shell made into scales. The bird is a fish with true scales only on his legs, and the other scales changed to feathers and feather quills, the fins changed to wings and the tail turned back fiat, like the lobster's.
You know, when you are listening to a story, if you happen to get to listening to something else for a few moments, how the rest of the story gets all mixed up? Then you ask mama to tell part of it over again.
Mother Nature seems to want to be so sure that we will not miss the smallest part of her story—the story of lower lives growing into higher all the time. So she keeps going back and telling it over and over again, whether we ask her to or not.
The higher the form of life, the more features of all forms of life it has in it. The crawfish, for example, couldn't show us what wings looked like because his people and their near relations didn't have any wings. Nor Mr. Fish couldn't show us what feathers are because he never was a bird. But the bird can show us the fins of the fish in his wings, the fish's scales on his legs, the jointed rings of the earthworm in his backbone, the whole earthworm in his intestines.
Not only because they are made of the same stuff, and because they have similar habits, are animals that look so different supposed to belong to the same great family, but there are many "connecting links" between different animals, like the fish that fly. Go far enough down the tree of life and you will find where one branch of the family is connected with some other branch that seems as different as can be.
Fish and birds, the owl and the pussy cat, all belong to one great family—the back-boned family. But among the back-boned family those that suckle their young, as the cat does, are higher than those
