Über Entwickelungsgeschichte der Thiere

Karl Ernst von Baer's \u00dcber Entwickelungsgeschichte der Thiere (On the Development of Animals), published in two volumes (1828 and 1837), is a foundational work in the field of embryology. In this two-volume publication, Baer synthesized existing knowledge on vertebrate development. He established the new science of comparative embryology, proposing that embryonic development progresses from simple to complex forms. Baer's research also led to significant discoveries, including the mammalian ovum and the notochord, and he is credited with proving the theory of epigenesis—that embryos develop from undifferentiated forms into specialized ones. This work laid the groundwork for future research into the causal analysis of development.12