As the slow tremendous change of the Earth's climate narrowed the forest, there was no longer food for all the woodland animals, and some of them ventured out into the open glades. Here was a final parting of the ways between the tapir who stayed in the woods and the horse-ancestor who went out into the open. He was as yet no bigger than a sheep, and still wore three toes on each foot, but the grass diet agreed with him, for his tribe soon grew to the size of an English donkey. The firmer ground no longer needed a wide tread to the foot. Slowly the second and fourth toes shrank away up the leg, and hung there like the dew claw of a dog, sometimes surviving more or less even in human times, as with Julius Cæsar's charger. The next ages evolved an animal the size of our ponies, running on one toe hardened to the hoof we know to-day. The snout diminished, while the tail became a fly whisk. [Sidenote: Varieties of the horse] So we have the beginning of a group of {9} animals the tarpan (Prejevalski) zebra, quagga and ass. They are so much alike that one cannot easily tell from the bones to which kind a skeleton belongs. We must think of them, then, as varieties of the horse. {10} CHAPTER II. THE ORIGIN OF HORSE VARIETIES. PROPOSITIONS. In the study of any subject, if we can only begin by clearing our vision, we shall have a sporting chance of avoiding muddle. The horse, like man or any other animal, reflects his environment in times past and present. 1. If all countries had equal lighting, all horses would reflect one colour. 2. If all countries were equally warm, all horses would grow the same thickness of coat. 3. If all countries had equal moisture, all horses would show similar endurance. 4. If all countries had one type of landscape, all horses would show the same markings. 5. If all countries had one soil, all horses would be of one build. 6. If all countries had one weight of forage to the acre, all horses would have one bulk. {11} 7. If all countries had one quality of forage, all horses would have one strength. 8. It follows that the study of light, heat, moisture, landscape, soil, and food should explain the origin of the wild types of horses. Our breeds are got by crossing from these varieties. If, therefore, the facts which we find out by study shall correspond with the reader's own experience of horses, no further proof is needed; but if they fail to appeal to the reader's sense and judgment, no balancing of proofs upon a point of falsehood will save a useless book from the flames which await waste paper. PART I. COLORATION BY SUNLIGHT. [Sidenote: Coloration by sunlight]