and Phylogeny that His's attack on Haeckel's recapitulation theory was far more fundamental than that of any empirical critic, as it effectively stated that Haeckel's "biogenetic law" was irrelevant.

Darwin proposed that embryos resembled each other since they shared a common ancestor, which presumably had a similar embryo, but that development did not necessarily recapitulate phylogeny: he saw no reason to suppose that an embryo at any stage resembled an adult of any ancestor. Darwin supposed further that embryos were subject to less