The general objectives are the understanding of the ear and its hearing processes in man and animals under normal and abnormal conditions. The specific objectives are the study of these processes in the lowermost vertebrates, the amphibians and teleost fishes, so as to reveal more clearly the difference from the higher types in reptiles, birds, and mammals. The methods of investigation include (1) the recording of electrophysiological responses of the ear during stimulation with sounds and (2) the examination of the auditory structures by dissection and by advanced histological techniques developed for this purpose to reveal the details of structure and in particular the forms of the tectorial tissues and their relations to the auditory hair cells. The results will be brought to bear on questions of evolutionary development within the vertebrate series.