Contents Prefatory Note by Thomas H. Huxley Preface Development and Creation Certain Proofs of the Doctrine of Descent The Skull Theory and the Ape Theory The Cell-Soul and Cellular Psychology The Genetic and Dogmatic Methods of Teaching The Doctrine of Descent and Social Democracy Ignorabimus et Restringamur Ernst Haeckel (1834-1919) received a thorough university education, and in 1862 became Professor of Zoology at Jena. He was the first outspoken Darwinian in Germany. He developed especially the theory that the history of the embryo follows the history of the race to which it belongs. Von Baer had made the first step in the theory, but Haeckel extended it and did much to prove its general truth. His investigations on the lower classes of marine organisms are classical.