In this article, I argue that species are mutable in Hegel’s philosophy of biology. While scholars have argued for the compatibility of Hegel’s philosophy and Darwin’s theory of evolution, none have dealt with the ontological status of species in their respective accounts. In order to make the case that for Hegel species are mutable, I first deal with a textual problem that in the 1827 edition of the Encyclopedia, the species concept appears after the sexual relationship, whereas in the 1830 (...) edition it appears prior. I argue that these different sequences entail different models for the species concept. By examining the conceptual development leading up to the account of species, on the one hand, and contemporary biological accounts of the status of species on the other, I argue that the 1827 model is more consistent both with Hegel’s method and with the species concept of contemporary biology. (shrink)