Explanation:
Von Baer's laws, published in 1828, responded to Johann Friedrich Heckel's recapitulation theory. Heckel worked at the University of Halle in Halle, Germany. In 1808, Heckel published his recapitulation theory. In his text, Heckel claimed that throughout ontogeny, embryos pass through successive stages that represent the adult forms of less complex organisms. He said that more complex organisms went through developmental stages that chronologically replayed the scala naturae, a hierarchical system of classification that places the least complex organisms on the bottom of the classification and the more complex organisms on the top. Later, Heckel's theory was termed the Heckel-Serres law, because Antoine Étienne Reynaud Augustin Serres, a physician in France, independently published a similar theory in 1821.
