It is in the receptors of the vertebrate retina that the characteristic visual process - the transduction of radiational energy into physiological activtty of a different kind - takes place. The way these receptors modify or redistribute the incident radiation and thereby control the light ab sorption by the visual pigments they contain, is the central theme of this book. As far back as 1843 Brucke put forward a well-reasoned model for the optics of a receptor, assuming simple ray optics, and it is already some forty-seven years since the dependence of receptor sensitivity on retinal angle of incidence was established experimentally as an important factor in human vision and as one by which the direction of alignment of receptors in the living eye might be determined. But it is to Professor J. M. Enoch, editor and author of several major contributions to this volume, that we owe the first experimental demonstration (in 1961) of the wave-mode propa gation of light in vertebrate visual receptors, as well as the results of some thirty years devoted research concerned with all questions of receptor optics, particularly directional sensitivity and receptor alignment, both for normal vertebrate eyes and for pathologically modified eyes. His work on the latter has opened up a whole range of clinical possibilities."

When seen from an outsider's vantage point, the development of knowledge in the sensory sciences must appear massive and the result of some carefully followed master plan. In reality, it is the result of numerous relatively independent human endeavors shaped by application of the scientific method. The comprehensive construction of quantitative theories of sense organ function has occurred only recently -but at an explosive rate prefaced by centuries of expansion in the physical sciences. Predicated on this growth, the twentieth century may become known as the age of the biological sciences. With the exception of a modest number of intellectual giants, there were few contributors to the foundations of the sensory sciences before the dawn of this century. At least 90% of existing knowledge has been produced by scientists working in laboratories founded since 1920. If any single scientist and his laboratory may be identified with the growth in the sensory sciences, it is EDGAR DOUGLAS ADRIAN, First Baron of Cambridge and leader of the Physiological Laboratory at Cambridge University, England. Lord ADRIAN'S influence upon the sensory sciences was great, not only in terms of his contribution to knowledge itself but also through the influence which he exerted upon numerous young scientists who spent weeks or years at the Cambridge laboratory and who later returned to their homelands and colleagues with the seeds of vigorous research and quantitative inquiry firmly implanted.