Choose the wrong statement with reference to the Mutation theory.
 (a) There are no intermediate stages in the course of evolution
 (b) Mutants are markedly different from parents
 (c) Mutants are subjected to natural selection
 (d) Mutations are cumulated over generations

Hint: The theory was related to the mutation that occurs due to the changes in the environment or heredity factors. It leads to evolution and may occur anytime spontaneously. It is an alternative to natural selection.

Complete step by step answer:
- Hugo de Vries explained the mechanism of evolution based on the gene structure which is also called mutation theory. This theory involves the changes that occur in the structure of the genes that are the result of the addition, deletion, inversion, or substitution of nucleotides.
- Mutation occurs leading to the differences between the parents and their offsprings. The mutation occurs spontaneously it is discontinuous and does not accumulate over generations. Natural selection is an alternative to the mutation.
- Hugo de Vries was well known for his work on mutation theory and found new forms of the Evening Primrose. He discovered many new varieties by taking several seeds from the plant.
- He then postulated that evolution occurs frequently on a large scale and this gives rise to the origin of the new species. These changes occur due to the mutation occurring in the sequence of the DNA resulting in the origin of new species.
- He experimented and stated that mutation occurs spontaneously according to environmental factors. This leads to natural selection as it selects those organisms that are adaptable to the environment and erases those organisms that are not adaptable to the new environment.
- The mutation occurs will be different from parents in the offspring and both will be different in characteristics.
So, the correct answer is ‘(d) Mutations are cumulated over generations’.

Note: Hugo de Vries was a Dutch botanist who was among the first geneticists to give about the concept of the genes and was working parallel to Gregor's Mendel who was working on mutation. He was the one to rediscover the laws of genetics. Hugo de Vries named genes as pangenes in his book Intracellular Pangenesis, after Darwin’s theory of Pangenesis.