Clifford Walter Emmens, Ph.D., D.Sc., Professor of Veterinary Physiology in the University of Sydney, has made distinguished contributions to reproductive physiology in animals and to statistical procedures and experimental techniques in hormone assays. This work has been embodied in over seventy publications in leading scientific journals, in a well-known text "Principles of Biological Assay" and in a number of review articles. In recent years he has made important contributions to the whole problem of artificial insemination by the development of means of low temperature storage of mammalian spermatozoa. In addition, he has taken a very active part in the work of the Physiological Society, the Society for Endocrinology and the Biometric Society and played a leading role in the development of the Sheep Biology Laboratory of C.S.I.R.O. at Parramatta.