Surface and deep electroencephalogram, electrocardiogram and behavior of 10 adult male rabbits were studied by slowly infusing fresh water or sea water in a speed of 0.3-2.0ml/min into the canulated trachea from the water reservoir attached to dripping apparatus until the death of the animal. From the behavior of the animal and EEGs and ECG findings, the course were divided into 4 stage : the 1 st