In 1976, when Springer-Verlag commissioned Professors Giebisch, Tosteson, and Ussing to edit what was destined to become a monumental five-volume Handbuch ( Membrane Transport in Biology , 1978 [Vols I, II, III] and 1979 [Vols IV A, B]), the subject of transepithelial secretion was still in its infancy. Not surprisingly, therefore, their Handbuch concentrated mainly on trans- epithelial absorption, although substantial chapters dealing with some secre- viz. Ion Transport Across the Choroid Plexus tory organs were included, (by E. M. Wright), Sweat Glands (by J. H. Thaysen), Lacrimal Gland (by J. H. Thaysen) and Transport Across Insect Excretory Epithelia (by J. P. H. Maddrell) in Volume III and Transport in Salivary and Salt Glands (by J. A. Young and E. W. Van Lennep), Gastric Secretion (by T. E. Machen and J. G. Forte), Transport Processes in the Exocrine Pan- creas (by I. Schulz and K. J. Ullrich), and Transport of Ions in Liver Cells (by M. Claret) in Volume IVB. The publication in 1977 of the seminal paper of Silva and his colleagues on the mechanism of secretion of salt and water in the salt excreting gland of the dogfish (American Journal of Physiology 233, F298-F306, 1977) provided physiologists with their first real insight into the mechanisms underlying transepithelial fluid secretion, however, and, in the ensuing years, interest in the topic has exploded as is evidenced by the numerous international symposia on exocrine secretion held since that date.