Abstract
About 11 years ago Ford & Benedek (1964) and Cummins, Knable & Yeh (1964) developed some fascinating new light-scattering techniques for the study of macromolecular motions in solution. Enthusiastic researchers have over the years endowed these new methods with a variety of colourful names, including optical mixing or light-beating spectroscopy, heterodyne or homodyne beating, intensity fluctuation spectroscopy, Rayleigh spectroscopy, and quasielastic or dynamic light scattering.