1. Three lead-methods for recording the EEG of rats were compared and it was found that the direct method gives the most accurate results.
2. Normal EEG of the adult rat is characterized by rhythmical 7-10 (6-12) per sec. basic waves and superimposed smaller fast waves. Alteration of pro-portionof these two components gave individual differences of normal records. Slow waves of less than 6 per sec. were also present but were not significant.
3. EEG of the new born rat showed basic waves, though irregular and small, and it was about 3 weeks after birth that the EEG became almost identi-cal with that of normal adult rats.
4. Until the 3rd or the 4th day after birth, no changes in EEG or move-ment were noted following electro-shock to the head. On the 4th or 5th day, a convulsive EEG pattern was noticed but it was about 7 days that the actual convulsion of limbs was associated with EEG changes.