* Marx evidently had a high regard for the organic chemist Freiherr Justus von Liebig (1803–73), who was a pioneer in the application of chemistry to agricultural problems. Liebig is referred to several times in both this volume of Capital and Volume 1, and it seems that Marx took from Liebig the concept of metabolism (Stoffwechsel) that he applied there, suitably transformed, to the analysis of the labour process (Chapter 7). The work that Marx refers to here is Liebig’s Die Chemie in ihrer Anwendung auf Agricultur und Physiologie,7th edn, 1862.