1. | Both Hugo de Vries and Darwin believed that it was mutation that caused evolution. |
2. | Both Hugo de Vries and Darwin believed that it was minor variations that caused evolution, not mutation. |
3. | Mutations are small and directional, while Darwinian variations are random and directionless. |
4. | Evolution for Darwin was gradual while de Vries believed mutation caused speciation and hence called it saltation (single-step large mutation). |