In early 1840s, Ludwig, in Berlin, met Emil Reymond, and through him became friends with Hermann Helmholtz and Ernst Brucke. Through them or with them, Ludwig rejected the assumption that the phenomena of living animals depend on special biological laws and vital forces different from those which operate in the domain of inorganic nature; and he sought to explain them by reference to the same laws as are applicable in the case of physical and chemical phenomena. 
In 1856, Ludwig, in his Textbook on Human Physiology, promoted the physico-chemical view.
- Chisholm, Hugh. (1911). “Karl Ludwig” (pg. 114) (WS), Encyclopedia Britannica, 17 (11th edition). Cambridge.
- Carl Ludwig – Wikipedia.