Progress in Theoretical Biology, Volume 4 discusses the theoretical aspects of genetic complementation and illustrates an allosteric enzyme model with positive feedback applied to glycolytic oscillations. The text also describes the states, observables, and the measurement process in quantum theory and biology; the use of biological macromolecules as measuring systems; as well as the structure, stability, and efficiency of ecosystems. The general theory of adaptation as well as the adaptive cognitive system are also encompassed. Biologists, cytologists, geneticists, and biophysicists will find the book invaluable.