The purpose of this book is well expressed in the Preface by the statement of the authors that each had a feeling that the problems of the origin of species had not been settled, and alone each one felt unable to attack and settle so momentous a question; but apparently they found strength in union and have attempted to settle the question of species-making. Most naive is their statement in the Introduction: "Our aim in writing this book has been twofold: In the first place, we have attempted to place before the general public in simple language a true statement of the present position of biological science. In the second place, we have endeavored to furnish the scientific men of the day with food for reflection."

Frank Finn (1868 1 October 1932) was an English ornithologist.