69 Mated for Life 396 70 Evidence of Conjugal Affection 400 71 Life in the Primordial Sea 410 72 Carboniferous Times 412 73 Mesozoic Flora and Fauna 415 74 Palæolithic Men Attacking Cave Bear 448 75 Era of Mind and Heart 462 FULL PAGE PLATES. From Photographs from Nature by A. RADCLYFFE DUGMORE. 1 Snapping Turtles Fighting Frontispiece FACING PAGE 2 Crab Waiting for Food Under a Rock 74 3 Box-tortoise Feeding on Fungus 200 4 Woodcock on Nest (showing protective coloring) 212 5 Red-eyed Vireo’s Two-Storied Nest With Cow-bird’s egg beneath 264 6 Long-billed Marsh Wren’s Nest 272 7 Chipping Squirrels Feeding 286 8 Wood Thrush Setting 402 LIFE AND IMMORTALITY. LIFE AND ITS CONDITIONS. All natural objects, roughly divided, arrange themselves into three groups, constituting the so-called Mineral, Vegetable and Animal kingdoms. Mineral bodies are all devoid of life. They consist of either a single element, or, if combined, occur in nature in the form of simple compounds, composed of more than two or three elements. They are homogeneous in texture, or, when unmixed, formed of similar particles which have no definite relations to one another. In form they are either altogether indefinite, when they are said to be amorphous, or have a definite shape, called crystalline, in which case they are ordinarily bounded by plane surfaces and straight lines. When mineral bodies increase in size, as crystals may do, the increase is produced simply by accretion. They exhibit purely physical and chemical phenomena, and show no tendency to periodic changes of any kind. Fossils or petrifactions, which owe their existence and characters to beings which lived in former periods of the earth’s history, cannot, though made up of mineral matter, be properly said to belong to the mineral kingdom.