Editing Embryo drawing (section)

===Wilhelm His (1831–1904)===
Wilhelm His was one of Haeckel's most authoritative and primary opponents advocating physiological embryology.<ref>Gould, ''Ontogeny and Phylogeny'', p. 189</ref> His ''Anatomie menschlicher Embryonen'' (Anatomy of human embryos) employs a series of his most important drawings chronicling developing embryos from the end of the second week through the end of the second month of pregnancy. In 1878, His begins to engage in serious study of the anatomy of human embryos for his drawings.  During the 19th century, embryologists often obtained early human embryos from abortions and miscarriages, postmortems of pregnant women and collections in anatomical museums.<ref>Hopwood, "Producing Development", p. 38</ref> In order to construct his series of drawings, His collected specimens which he manipulated into a form that he could operate with.

In His' ''Normentafel'', he displays specific individual embryos rather than ideal types.<ref>Hopwood, "Producing Development", p. 36</ref> His does not produce norms from aborted specimens, but rather visualizes the embryos in order to make them comparable and specifically subjects his embryo specimens to criticism and comparison with other cases.  Ultimately, His' critical work in embryonic development comes with his production of a series of embryo drawings of increasing length and degree of development.<ref>Hopwood, "Producing Development", p. 50</ref> His' depiction of embryological development strongly differs from Haeckel's depiction, for His argues that the phylogenetic explanation of ontogenetic events is unnecessary.  His argues that all ontogenetic events are the "mechanical" result of differential cell growth.<ref>Di Gregorio, ''From Here to Eternity'', p. 277</ref> His' embryology is not explained in terms of ancestral history.

The debate between Haeckel and His ultimately becomes fueled by the description of an embryo that [[Wilhelm Krause (anatomist)|Wilhelm Krause]] propels directly into the ongoing feud between Haeckel and His.  Haeckel speculates that the [[allantois]] is formed in a similar way in both humans and other mammals.  His, on the other hand, accuses Haeckel of altering and playing with the facts.  Although Haeckel is proven right about the allantois, the utilization of Krause's embryo as justification turns out to be problematic, for the embryo is that of a bird rather than a human.  The underlying debate between Haeckel and His derives from differing viewpoints regarding the similarity or dissimilarity of vertebrate embryos.  In response to Haeckel's evolutionary claim that all vertebrates are essentially identical in the first month of embryonic life as proof of common descent, His responds by insisting that a more skilled observer would recognize even sooner that early embryos can be distinguished.  His also counteracts Haeckel's sequence of drawings in the ''Anthropogenie'' with what he refers to as "exact" drawings, highlighting specific differences.  Ultimately, His goes so far as to accuse Haeckel of "faking" his embryo illustrations to make the vertebrate embryos appear more similar than in reality.  His also accuses Haeckel of creating early human embryos that he conjured in his imagination rather than obtained through [[empirical]] observation.  His completes his denunciation of Haeckel by pronouncing that Haeckel had "'relinquished the right to count as an equal in the company of serious researchers.'"<ref>Hopwood, "Producing Development", p. 61</ref>