Electroencephalographic studies were carried out on chickens to determine the normal electroencephalogram (EEG) patterns from wakefulness to sleep and the effect of anesthesia. Sixteen electrodes were fured to the frontal and parietal bones. EEG was recorded under unstressed condition. I n the excited state, fast waves of 30 to 60 cps and of low amplitude were predominant. In the resting period, these waves shifted to slower ones of 14 to 24 cps, the amplitude remaining low as in the excited state. As the bird fell asleep, three main stages could be distinguished according to the correlation between the EEG patterns and behavioral states. Under ether anesthesia, four stages could be distinguished according to the EEG patterns and the responsiveness to afferent stimuli. By increasing the dose of nernbutal, the correlation between the EEG pattern and the depth of anesthesia was studied.The "spindle burst," or "barbiturate burst," and the "fast wave" shown i n mammals by the injection of barbiturates were not observed in the chicken.

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