The purpose of this study is to examine research on formative principles based on natural laws conducted in the 19th century, focusing on their relationship with functionalist design. The 19th century was a period when the conviction emerged that research into the mechanisms of form-giving in nature could serve as both creative inspiration and motivation for design. Before institutional movements such as the German Federation of Crafts, Jugendstil, and Bauhaus, which tried to establish functionalist design, researchers from various fields had already examined form and function. The discourse of functionalist design is so deep and broad that it is not easy to define, but it can be interpreted based on the discourse related to functionalism mainly discussed in the field of architecture. If we summarize the reasons why functional design is more appropriate than formal design through analogies and metaphors used by various scholars, it converges into organic analogy based on nature, mechanical analogy based on mechanical efficiency, and moral analogy based on ethical ideals. In this study, with regard to organic analogy, we aimed to examine the process of the transition of research on nature into a design approach inspired by nature by reviewing materials such as sketches, sculptures, photographs, etc., of researchers who were active in the fields of art, architecture, and design, including Haeckel, Blossfeldt, and Dresser. In addition, we aimed to point out the limitations of previous studies on the influence of the 19th-century formal exploration on the Art Nouveau movement. We also sought to illuminate that functionalist design had already commenced before the emergence of the Art Nouveau movement as a formal movement. The significance of this study is to reconsider the beginning of functionalist design from an institutional perspective, recorded in the first half of the 20th century, and to expand the genealogy of functionalism from a more multi-layered and discursive perspective that is implied by the efforts to explore form in the 19th century.