The Last Link: Our Present Knowledge of the Descent of Man

The Riddle of the Universe at the close of the nineteenth century

Freedom in Science and Teaching. from the German of Ernst Haeckel

The Evolution of Man — Volume 1

The History of Creation

Monism as Connecting Religion and Science

The Evolution of Man

The Wonders of Life: A Popular Study of Biological Philosophy

The Last Link: Our Present Knowledge of the Descent of Man

Freedom in Science and Teaching. from the German of Ernst Haeckel

The Riddle of the Universe at the close of the nineteenth century