Nicolas-Théodore was attracted to chemistry by Lavoisier's discoveries, and he adopted Lavoisier's new system of chemistry early in life. He became interested in the chemistry and physiology of plants, including gas exchange and the ways that different soils affected their growth. His early papers on these subjects laid the groundwork for some of the chapters in his magnum opus, "Recherches chimiques sur la Végétation" ("Chemical Research on Plant Growth"), published in 1804. This book was the first summation of the fundamental process of photosynthesis and a major contribution to the understanding of plant physiology. In contrast to some of his predecessors in the field of photosynthesis research, Saussure based his conclusions on extensive quantitative data that he had collected.