According to A mutation was gradual while de Vries believed mutation caused B and hence called it C
| A | B | C | |
| 1. | Lamarck | Saltation | Speciation |
| 2. | Thomas Malthus | Speciation | Natural selection |
| 3. | Darwin | Speciation | Saltation |
| 4. | Wallance | Natural selection | Speciation |