If, contrary to the generally accepted idea, within the female organism have been developed those elements which form the basis of human progress, or, if the higher faculties are transmitted through the mother, henceforth all examinations into primitive conditions and all research into the causes which underlie existing institutions must be carried on with reference to this particular fact. Only through a thorough understanding of the principles or forces which govern human development, and a just appreciation of the source whence these principles have sprung, may we hope to gain a clear understanding of the past history of the race, or to perceive the true course to be pursued toward further development. Through the investigation of facts revealed in the records of Geology, and through the study of comparative Embryology and Anatomy, or through an understanding of Zoölogy and Anthropology, man has well-nigh solved the problem of his origin, or has almost proved his connection with and development from the lower orders of life, but of the countless ages which intervened between the era of our ape-like progenitors and the dawn of organized society, little may be known without a correct knowledge of the inheritance received by mankind from creatures lower in the scale of being. Only by a careful study of the constitutional bias acquired throughout the entire line of development, are we enabled to note the motives or forces by which primitive society was controlled, or to form a just conclusion relative to the early conditions of human society and its subsequent progress. Through the attention which in these later years has been directed toward surviving tribes in the so-called middle and later stages of savagery, and in the three successive periods of barbarism, have doubtless been revealed many of the processes by which mankind have reached their present condition. Much of the information, however, which has been obtained by these inquiries still lacks that accuracy in detail demanded by exact science; but, so soon as the array of facts which the last half-century has brought to bear upon this subject shall have been correctly interpreted, logically arranged, intelligently classified, and without prejudice brought into line with the truths involved in the theory of natural development, there will doubtless be approximated a system of truth which will furnish a safe and trustworthy foundation for a more thorough research into the history of the human race.