Karl Marx’s Ecosocialism. Kohei Saito

also reflected in his theory of metabolism, in terms of which he supported the “humus theory” of Gerardus Mulder in Utrecht and criticized Liebig’s “mineral theory.” Liebig maintained, as a result of various chemical experiments, that the direct effect of humus—that is, the dark material of decayed plants in the top layer of soil—upon plant growth occurs only as a result of its decomposition into water and carbonic acid. In contrast, Moleschott and Mulder insisted, in agreement with Albrecht Thaer, on the direct and essential contribution of a soil nutrient called Dammsäure contained in humus for plant growth: “In contrast [to Liebig,] Wiegmann and Mulder, getting rid of any doubt, proved through experiments that neither carbonic acid nor ammonia can replace the effect of Dammsäure.”⁶¹

      As he counted ammonium compounds of Dammsäure as the “most important substance of nourishment,” Moleschott undervalued Liebig’s theory of inorganic substances for plant growth, a theory still valid today, and ignored the concrete chemical reactions of bonding and dissolving among various organic and inorganic substances in the atmosphere, soil, and plants.⁶² While Liebig argued for the importance of a chemical analysis of soil composition, Moleschott reduced the chemical and physiological process of plant growth into an abstract and overgeneralized “metempsychosis,” forgoing concrete investigations.

      In this metempsychosis that subsumes everything under it humans also lose their own labor-mediated historicity and functions within the social and natural metabolism. Moleschott simply stated that humans as ephemeral beings are decomposed into “Dammsäure and ammonia” in the soil after death, so that plants can again grow on the soil without exhausting it: