The objects of science education are transformed, degraded and disappeared for many reasons, and sometimes take other things with them when they go. This close reading of an undergraduate physiology laboratory report demonstrates how the kymograph was never a stand-alone instrument, but intertwined with conceptual frameworks and technical skills, laboratory amenities, materials, animal supply, technicians. Replacing the obsolete kymograph entails changing all of that. Histories usually focus on progress associated with better measurements and fewer complications; instead, I focus on the complications themselves: what did students learn from them? What laboratory culture disappeared along with them? How have curriculum and pedagogy been transformed by their removal? The connection between progress and demise raises uncomfortable challenges for laboratory pedagogy, and for museum practice: what is laboratory education really about, and what kinds of heritage should museums, libraries and archives preserve to document it?