In the latter part of the summer of 1926, several patients suffering from the injurious effects of heat were admitted to the medical service of the Naval Hospital, Washington, D. C., and all recovered uneventfully except one. This patient was left with some mental confusion and somatic delusions which he still had at the time of discharge from the hospital. A review of the subject at this time revealed that very little is known of the mechanism of production of the various forms of heat injury. As a preparatory study to experimental investigation in heat-stroke in dogs, it was decided to make a study