The theories in the field of organic evolution were propounded by Darwin, Hugo de Vries, Lamarck and Huxley. Darwin in 1859 explained the theory of natural selection and wrote a book The origin of species. Hugo de Vries, a Dutch botanist, propounded mutation theory in 1901. Lamarck explained the theory of organic evolution on the basis of inheritance of acquired character and wrote a book Philosophic zoologique, whereas Huxley performed a number of experiments to remove the objections against Darwins theory.