Man was the last to come but the first to use his brain for the purpose of conquering the forces of nature. That is the reason why we are going to study him, rather than cats or dogs or horses or any of the other animals, who, all in their own way, have a very interesting historical development behind them.

      In the beginning, the planet upon which we live was (as far as we now know) a large ball of flaming matter, a tiny cloud of smoke in the endless ocean of space. Gradually, in the course of millions of years, the surface burned itself out, and was covered with a thin layer of rocks. Upon these lifeless rocks the rain descended in endless torrents, wearing out the hard granite and carrying the dust to the valleys that lay hidden between the high cliffs of the steaming earth.

      Finally the hour came when the sun broke through the clouds and saw how this little planet was covered with a few small puddles which were to develop into the mighty oceans of the eastern and western hemispheres.

      Then one day the great wonder happened. What had been dead, gave birth to life.

      The first living cell floated upon the waters of the sea.

      For millions of years it drifted aimlessly with the currents. But during all that time it was developing certain habits that it might survive more easily upon the inhospitable earth. Some of these cells were happiest in the dark depths of the lakes and the pools. They took root in the slimy sediments which had been carried down from the tops of the hills and they became plants. Others preferred to move about and they grew strange jointed legs, like scorpions and began to crawl along the bottom of the sea amidst the plants and the pale green things that looked like jelly-fishes. Still others (covered with scales) depended upon a swimming motion to go from place to place in their search for food, and gradually they populated the ocean with myriads of fishes.

      Meanwhile the plants had increased in number and they had to search for new dwelling places. There was no more room for them at the bottom of the sea. Reluctantly they left the water and made a new home in the marshes and on the mud-banks that lay at the foot of the mountains. Twice a day the tides of the ocean covered them with their brine. For the rest of the time, the plants made the best of their uncomfortable situation and tried to survive in the thin air which surrounded the surface of the planet. After centuries of training, they learned how to live as comfortably in the air as they had done in the water. They increased in size and became shrubs and trees and at last they learned how to grow lovely flowers which attracted the attention of the busy big bumble-bees and the birds who carried the seeds far and wide until the whole earth had become covered with green pastures, or lay dark under the shadow of the big trees.

      But some of the fishes too had begun to leave the sea, and they had learned how to breathe with lungs as well as with gills. We call such creatures amphibious, which means that they are able to live with equal ease on the land and in the water. The first frog who crosses your path can tell you all about the pleasures of the double existence of the amphibian.

      Once outside of the water, these animals gradually adapted themselves more and more to life on land. Some became reptiles (creatures who crawl like lizards) and they shared the silence of the forests with the insects. That they might move faster through the soft soil, they improved upon their legs and their size increased until the world was populated with gigantic forms (which the hand-books of biology list under the names of Ichthyosaurus and Megalosaurus and Brontosaurus) who grew to be thirty to forty feet long and who could have played with elephants as a full grown cat plays with her kittens.

      Some of the members of this reptilian family began to live in the tops of the trees, which were then often more than a hundred feet high. They no longer needed their legs for the purpose of walking, but it was necessary for them to move quickly from branch to branch. And so they changed a part of their skin into a sort of parachute, which stretched between the sides of their bodies and the small toes of their fore-feet, and gradually they covered this skinny parachute with feathers and made their tails into a steering gear and flew from tree to tree and developed into true birds.

      Then a strange thing happened. All the gigantic reptiles died within a short time. We do not know the reason. Perhaps it was due to a sudden change in climate. Perhaps they had grown so large that they could neither swim nor walk nor crawl, and they starved to death within sight but not within reach of the big ferns and trees. Whatever the cause, the million year old world-empire of the big reptiles was over.

      The world now began to be occupied by very different creatures. They were the descendants of the reptiles but they were quite unlike these because they fed their young from the “mammæ” or the breasts of the mother. Wherefore modern science calls these animals “mammals.” They had shed the scales of the fish. They did not adopt the feathers of the bird, but they covered their bodies with hair. The mammals however developed other habits which gave their race a great advantage over the other animals. The female of the species carried the eggs of the young inside her body until they were hatched and while all other living beings, up to that time, had left their children exposed to the dangers of cold and heat, and the attacks of wild beasts, the mammals kept their young with them for a long time and sheltered them while they were still too weak to fight their enemies. In this way the young mammals were given a much better chance to survive, because they learned many things from their mothers, as you will know if you have ever watched a cat teaching her kittens to take care of themselves and how to wash their faces and how to catch mice.

      But of these mammals I need not tell you much for you know them well. They surround you