THE RESPIRATORY activity of isolated surviving tissues has been extensively investigated in the last 25 years. The respiration of the cornea has also been studied, but, as compared with what is known of other tissues, knowledge concerning its metabolic activities is somewhat sketchy and confusing. The present study was undertaken in an attempt to fill in some of the gaps remaining in the present concept of corneal respiration and to help in clarifying some of the contradictory reports that have appeared in the literature. I. RESPIRATION OF THE CORNEA IN AIR The first question to be studied was: Can the cornea utilize oxygen from the surrounding atmosphere? Because of its unique position in the body, i. e., its being remote from the blood stream and exposed to the air, this question has interested many investigators. More than 50 years ago, in 1899, long before the Barcroft-Warburg manometric technic for the