With recording electrodes leading from an intact and a cauterized area on the cerebral cortex of the cat, the effects of ether, avertin and pentobarbital anesthesia on the cortical action potentials, with and without sensory stimulation (sciatic nerve), were studied. Action potential patterns under light or moderate avertin or pentobarbital anesthesia differ little from those without anesthesia, showing waves from 5 to 20 per sec. As the anesthesia with these drugs is made very deep the waves become less frequent, but not smaller, until the base-line becomes smooth. Sciatic stimulation then evokes a large electric response (single splke) with latency of 30-60 msec. and duration little greater. Under ether the action potentials appear as small waves of 30-40 per sec., sometimes superimposed on larger waves, 1-3 per sec. Deeper anesthesia reduces amplitude of fast waves without changing frequency. Sciatic stimulation under ether causes negative shift of base-line, increased amplitude of fast waves and gradual onset of regular waves of 2-3 per sec. Under deep ether the effects of stimulation disappear, while the fast waves are still visible. Ether apparently blocks the afferent approach, and thus differs from the other drugs, which leave the cortex accessible to sensory stimulation after spontaneous waves have ceased. Local differences in pattern are less than the differences characterizing the different drugs. Asphyxia gives a cortical plcture like very deep avertin or pentobarbital anesthesia, while enhancing a splnal reflex.