BIRDS' NESTS, EGGS, AND EGG-COLLECTING INTRODUCTION. =The Problem of Preservation.=--As a rule the first subject to which the young naturalist turns his attention is the most interesting one within his reach, and that subject is undoubtedly found in bird-life; particularly that portion of it which concerns the nests, eggs, young, and various modes of nidification, for this is really the kernel of ornithology. Its details teach him the utility of systematic study and close observation, two important points in all matters of scientific research. It is my intention in the following pages to furnish as full and interesting particulars on Oology, which may fairly be entitled to the dignity of a science, as can be found, or is likely to be required, in any popular treatise of its modest compass. This particular branch of natural history has been until lately but indifferently studied--in fact, considered unworthy of higher attention than that which could be bestowed upon it by schoolboys. People have been content to know that the wonderful architecture and mechanism of a bird's nest was the outcome of a force vaguely known as _instinct_, without taking the trouble to discover its workings, extent, or limits. Instinct is an extremely difficult power to define, and whether it be described as "hereditary habit," or simply accepted as an unknown law of Nature blindly followed by its possessor, it cannot be denied that it is the outcome of conditions, and always amenable to them. If the word mystery were often substituted for instinct, it would not be at all out of place, for it means quite as much. It is more honest to acknowledge our ignorance than to fence it round by speculative theory or cover it by almost meaningless phrases. Survival of the fittest is undoubtedly Nature's great law. With this end in view she governs and regulates the actions of birds in exactly the same way as she controls the colour and character of their plumage, shape, size, tint, and number of their eggs, first movements of their young, and other peculiarities we do not understand.