Auguste-Henri Forel (1848-1931) was a Swiss myrmecologist, neuroanatomist and psychiatrist, notable for his investigations into the structure of the human brain and that of ants. Forel had a diverse and mixed career as a thinker on many subjects. He published papers on insanity, prison reform, and social morality. He is considered a co-founder of the neuron theory. Forel is also known for his early contributions to sexology. Around 1900 Forel was a eugenicist. Forel suffered a stroke that paralyzed his right side in 1912, but he taught himself to write with his left hand and was able to continue his studies. He died at the age of 82.