Perfusing presvollen deepithelialized rabbit cornea in vitro on its endothelial side with balanced salt solution containing physiological glucose concentration and 10–6M adenosine, we can obtain“temperature reversal”from 500–520p to less than 400µ, during 7 hours. Low concentrations of adenosine improve the fluid pump supposedly by inhibiting adenylate cyclase, since c-AMP inhibits the pump.