Twenty adult cats were utilized for this study under unanesthetized condition. Penicillin was locally given in various parts of cortex and subcortical nucleus or thalamus to elicit epileptogenic discharges and sodium amobarbital was intracarotidly injected to give arise transient functional depression of hemisphere. EEG was followed up in the course of this experiment. 1) Local application of penicillin into cortex or subcortical nucleus or thalamus considerably elicited epileptogenic discharges. 2) In case of focal cortical epileptogenic discharge, the first spike appearing at the neighbouring area of the focus was followed to be associated with the synchronous spike discharge at the opposite side and then the focal seizure discharge was built. The discharge was occaionally interrupted by the interictal state, building, in some of the cases, the final stage of generalized seizure discharge. 3) So was noted in its appearance and process in case of focal subcortical epileptogenic discharge. But there was a more tendency of transmission of its activity to the opposite side in comparison with the cortical epileptogenic discharge. 4) The epileptogenic discharge originated from unilateral cortical focus was abolished or inhibited by means of ipsilateral intracarotid injection of 5 to 10 mg sodium amobarbital, but was not affected by the contralateral administration. However, either side of the injection could not inhibit the discharge activity after it became a focal seigure discharge. 5) Subcortically elicited epileptogenic discharge, in contrast, could not be interfered by either side of the intracarotid administration. 6) In cases of both focal cortical and subcortical discharge, intracarotid injection of sodium amobarbital manifested a tendency of flattening and slowing of back ground activity at the injected side, but not at the opposide side. 7) The intracarotid administration could not activate the epileptogenic discharges either from cortex and subcortex.