Introduction Paul Ehrlich and his Receptor Concept The Development of the Concept of Drug Receptors in the Physiological Research of J. N. Langley The Receptors and Scientific Pharmacology I: The Critics of the Receptor Idea and Alternative Theories of Drug Action, c. 1905-1935 The Receptors and Scientific Pharmacology II: The Critics of the Receptor Idea and Alternative Research Strands: The Transmitter Theory, c. 1905-1935 Quantitative Arguments...