1. Darwin took into consideration minute fluctuating variation as principal factors. But these are neither heritable nor are part of evolution.
2. Darwin did not distinguish somatic and germinal variation and considered all variations are heritable. ‘Arrival of the fittest’ was not explained by him.
3. Darwin was unable to explain the cause, origin and inheritance of variations and of vestigial organs.
4. He also could not explain extinction of species.
5. Gradual accumulation of useful variations forms the new species, but their intermediate forms were not recognised.
6. Darwin could not explain existence of neutral flowers and the sterility of hybrids.
