Historical knowledge cannot be replaced by any other branch of science. It is clear that the prejudices that stand in the way of a general recognition of this "natural anthropogeny" are still very great; otherwise the long struggle of philosophic systems would have ended in favour of Monism. But we may confidently expect that a more general acquaintance with the genetic facts will gradually destroy these prejudices, and lead to the triumph of the natural conception of "man's place in nature." When we hear it said, in face of this expectation, that this would lead to retrogression in the intellectual and moral development of mankind, I cannot refrain from saying that, in my opinion, it will be just the reverse; that it will promote to an enormous extent the advance of the human mind. All progress in our knowledge of truth means an advance in the higher cultivation of the human intelligence; and all progress in its application to practical life implies a corresponding improvement of morality. The worst enemies of the human race--ignorance and superstition--can only be vanquished by truth and reason. In any case, I hope and desire to have convinced the reader of these chapters that the true scientific comprehension of the human frame can only be attained in the way that we recognise to be the sole sound and effective one in organic science generally--namely, the way of Evolution. INDEX. Abiogenesis. Accipenser. Abortive ova. Achromatin. Achromin. Acoela. Acoustic nerve, the. Acquired characters, inheritance of. Acrania, the. Acroganglion, the. Adam's apple, the. Adapida. Adaptation. After-birth, the. Agassiz, L. Age of life. Alimentary canal, evolution of the. structure of the. Allantoic circulation, the. Allantois, development of the. Allmann. Amblystoma. Amitotic cleavage. Ammoconida. Ammolynthus. Amnion, the. formation of the. Amniotic fluid, the. Amoeba, the. Amphibia, the. Amphichoerus. Amphigastrula. Amphioxus, the. circulation of the. coelomation of the. embryology of the. structure of the. Amphirhina. Anamnia, the. Anatomy, comparative. Animalculists. Animal layer, the. Annelids, the. Annelid theory, the. Anomodontia. Ant, intelligence of the. Anthropithecus. Anthropogeny. Anthropoid apes, the. Anthropology. Anthropozoic period. Antimera. Anura. Anus, the. Anus, formation of the. Aorta, the. development of the. Ape and man. Ape-man, the. Apes, the. Aphanocapsa. Aphanostomum. Appendicaria. Appendix vermiformis, the. Aquatic life, early prevalence of. Ararat, Mount. Archenteron. Archeolithic age. Archicaryon. Archicrania. Archigastrula. Archiprimas. Arctopitheca. Area, the germinative. Aristotle. Arm, structure of the. Arrow-worm, the. Arterial arches, the. cone, the. Arteries, evolution of the. Articulates, the. skeleton of the. Articulation. Aryo-Romanic languages, the. Ascidia, the. embryology of the. Ascula. Asexual reproduction. Atlas, the.