Revisiting Julius Sachs’s “Physiological Notes: II. Contributions to the Theory of the Cell. a) Energids and Cells” (1892)

Abstract

Julius Sachs (1832–1897), who has been quite rightly called “the father of plant physiology,” was a German physiologist of international standing, whose research interests contributed to virtually every branch of the plant sciences, and whose work presaged plant molecular biology and systems biology. Here, we focus on one of his last publications, from 1892, wherein he argued that the term “cell” (Zelle) is misleading and should be replaced by “energid” (Energide), which he defined as “a nucleus together with the corresponding protoplasm that is governed by it,” based on his observations of coenocytic algae such as Caulerpa whose nuclei “can only control” so much cytoplasm. Although most of his colleagues did not accept this novel terminology for the description of the “basic, minimal living unit” (Elementarorganismus) of animals, plants, and microbes, we argue that the energid concept prefigured the subsequent discovery of mRNA. We also argue that the resistance to the energid concept revolved around a deep-seated philosophical debate between those adhering to cell theory versus organismal theory. The first English translation of the seminal work by Sachs, “Physiologische Notizen. II. Beiträge zur Zellentheorie. a) Energiden und Zellen,” originally published in Flora (75: 57–67, 1892), is provided as a separate article in this volume as part of the journal’s “Classics in Biological Theory” collection (https://doi.org/10.1007/s13752-022-00399-w); the original German version is available here as supplementary material in the online version of this article.