Evolution

Species and Varieties, Their Origin by Mutation

New Perspectives on Horned Dinosaurs

Schenk's Theory: The Determination of Sex

Pioneers of Evolution from Thales to Huxley

Biology and Its Makers

The genetic and the operative evidence relating to secondary sexual characters

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

The True and False Theory of Evolution

The Effect of External Influences upon Development

Facts and Arguments for Darwin

The Butterfly Hunter

Humanology

Science & Cosmic Messengers

Creatures Born of Mud and Slime

The Genesis of Nature and the Nature of Genesis

The Social Behavior of Older Animals

American Snakes

Nature Strange and Beautiful

For Red Hot Blot to Blue Singing Whale

The Modes of Origin of Lowest Organisms