ABSTRACT: Historiography is becoming more critical of the typology/ population dichotomy introduced by Ernst Mayr. Therefore, one should look again at the problem of species in non-Darwinian theories: neo-Lamarckism and orthogenesis, and consider the possibility that this problem was overly simplified. What can be seen in both of them is the existence of a tension between the idea of evolution and the essence of species. In neo-Lamarckism, this tension was resolved by recognizing species as static entities which changed only when triggered by external stimulus. In orthogenesis, evolution was seen as constant phenomena and species – as naturally changeable entities. However, orthogeneticists assumed that not only species, but also whole phyletic lines had essences that constrained their further evolution. Thus, in both cases we can see interpretation of species in tune with essentialism, but essentialism is widely differently integrated with each of these concepts of evolution.