An attempt will be made to identify the active transport of an ion responsible for the pump in the corneal endothelium by simultaneously measuring the flux of water and two ions, as well as the electrical potential across the layer. Particular attention will be paid to the transport of HCO3 and CO2, which will be separated by means of pH changes in the medium. Endothelial layers will be grown in tissue culture and it will be seen if it can be induced to show active pumping in this state. These layers will be tested as donor endothelial grafts. Attempts will be made to prolong the life of the cells by supplying them with substrates, particularly those required for lipid synthesis. A study of the mechanism of excitation of corneal nerves will be initiated. Whether temperature and touch are mediated through the same nerve endings will be re-examined in an isolated corneal preparation. The nerve-excitation mechanism will be studied by searching for synergistic action between stimuli. An attempt to find whether the nerves are stimulated by a neurotransmitter released from the epithelial cells will be made by using microstimuli which can be limited to a small area of the cell.