Abstract
Ernst Brücke's 1861 essay Die Elementarorganismen has often been cited as a watershed in the history of physiology as well as in the history of cell theory. In its time it was widely read as a reform of animal cell theory, shifting the concept of the cell away from Schleiden and Schwann's original cell schema of a membranous vesicle with a nucleus, and towards the protoplasm theory that had developed in botany, centered on the cell's living contents. It was also notorious for its arguments against the necessity of both the nucleus and the cell membrane. An English translation of "The Elementary Organisms" is presented for the first time in this journal issue, with annotations and illustrations, https://doi.org/10.1007/s10739-024-09773-9 . Brücke's essay was not only an intervention into cell theory: historians can read it as a continuation of debates on the nature of the organism and theories of organization, and as an epistemological meditation on the microscope. In addition, although Brücke was known as a founder of the Berlin school of organic physics, "The Elementary Organisms" shows how he combined an avant-garde physicalist physiology with a much older tradition of comparative anatomy and physiology. The following introductory essay will provide a scientific biography of Ernst Brücke up to 1863, with background on debates on biological organization, cell theory, and muscle histology.