Embryo Drawing - Famous Embryo Illustrators - Karl Ernst Von Baer (1792-1876)

Karl Ernst Von Baer (1792-1876)

Haeckel was not the only one to create a series of drawings representing embryonic development. Karl E. von Baer and Haeckel both struggled to model one of the most complex problems facing embryologists at the time: the arrangement of general and special characters during development in different species of animals. In relation to developmental timing, von Baer's scheme of development differs from Haeckel's scheme. Von Baer's scheme of development need not be tied to developmental stages defined by particular characters, where recapitulation involves heterochrony. Heterochrony represents a gradual alteration in the original phylogenetic sequence due to embryonic adaptation. As well, von Baer early noted that embryos of different species could not be easily distinguished from one another as in adults.

Von Baer’s laws governing embryonic development are specific rejections of recapitulation. As a response to Haeckel’s theory of recapitulation, von Baer enunciates his most notorious laws of development. Von Baer’s laws state that general features of animals appear earlier in the embryo than special features, where less general features stem from the most general, each embryo of a species departs more and more from a predetermined passage through the stages of other animals, and there is never a complete morphological similarity between an embryo and a lower adult. Von Baer’s embryo drawings display that individual development proceeds from general features of the developing embryo in early stages through differentiation into special features specific to the species, establishing that linear evolution could not occur. Embryological development, in von Baer’s mind, is a process of differentiation, “a movement from the more homogeneous and universal to the more heterogeneous and individual.”

Von Baer argues that embryos will resemble each other before attaining characteristics differentiating them as part of a specific family, genus or species, but embryos are not the same as the final forms of lower organisms.