The presentation will focus on the glass objects fabricated by Leopold and Rudolph Blaschka. Around 1860 to 1936 father and son created thousands of lifelike models of marine invertebrates as decorative items and teaching resources for universities and scientific collections in Europe and the U.S. Their lifelike appearance, delicate details and the fact that they are completely made of glass still exerts fascination today. Their display of organicist aesthetics, clearly visible for example in the jellyfish’s relations of symmetry, places the glass models in the context of art nouveau. Aside from this they are also embodiments of a scientific worldview. The Blaschkas knew the relevant literature on marine life and botany, they observed organisms in the field and they corresponded with leading scientists. While they visited aquariums to witness marine animals, set out a garden and Rudolph even undertook a botanical expedition, many of their models were made from drawings. Of special importance in this context were the illustrations of Ernst Haeckel, who was an early patron of the Blaschkas and lent them books from his own library. Models like the glass radiolarians were completely based on the already idealized pictures of Haeckel, as the Blaschkas did usually not work with a microscope. All this points to the assumption that the glass models were not just mimetic copies of nature but that different forms of mimesis, of translation and representation were at play. They not only represent something, they also transform and reshape phenomena and thereby constitute an area that is at least partially autonomous from the phenomena themselves as well as from theories. Science studies and especially Actor-Network-Theory (ANT) have shown that such objects require networks that stabilize them and allow them to circulate as coherent entities. My talk will investigate the complex relationships and circumstances that made the Blaschka models possible. Which role did the different media (paper, glass), the different skills (biological observation, drawing, glassmaking) and the different forms of knowledge (biology, craft knowledge) play in the making of the models? Furthermore, how were the models themselves depicted and described, and in which different contexts did they themselves or representations turn up?