- DARWIN & DARWINISM | Home | Human Nature Review | What's New | Search | On the Tendency of Varieties to Depart Indefinitely from the Original Type. by Alfred Russel Wallace written at Ternate, February, 1858 Instability of Varieties supposed to prove the permanent distinctness of Species ONE of the strongest arguments which have been adduced to prove the original and permanent distinctness of ...www.human-nature.com/darwin/archive/arwallace.html