The difficulty of keeping planktonic organisms alive in captivity has greatly hindered experimental studies of their physiology and behaviour. This has especially been the case with the plankton of the deep sea. Up to the present our studies of these organisms have been largely morphological and distributional and it is clear that to learn more about their ecological relationships we must find means of keeping them alive to study their metabolism and behaviour experimentally. With this end in view attempts have been made to keep some oceanic plankton animals alive in the laboratory on board ship and ashore.