Chemist Nicholas-Théodore de Saussure published Recherches chimiques sur la végetation in Paris in 1804. In this foundation work on phytochemistry, Saussure analyzed the chief active components of plants, their synthesis and decomposition. He specified the relationships between vegetation and the environment. He showed that plants grown in closed vessels took their entire carbon content from the enclosed gas, and thus demolished the old theory that plants derive carbon from the so-called "humus" of the soil. Conversely, he demonstrated that the carbon content of soil is produced by vegetation.