 He posited that instead of linear progression, embryos started from one or a few basic forms that are similar in different animals, and then developed in a branching pattern into increasingly different organisms.Defending his ideas, he was also opposed to Charles Darwin's 1859 theory of common ancestry and descent with modification, and particularly to Ernst Haeckel's revised recapitulation theory with its slogan "ontogeny recapitulates phylogeny".Von Baer's laws are a series of statements generally summarised into four points.