It is generally recognized that the hypothalamus contains centers regulating autonomic activity. Experimental evidence which points to this conclusion has been obtained as a result of gross lesions or extirpation of this region, or by the injection of chemicals into the base of the brain. Karplus and Kreidl1 (1910) have supplied further data by making transverse ablations through the diencephalon and stimulating the exposed end. Never before has a systematic exploration of the intact hypothalamus with electrical stimulation been undertaken. The foundation for such an investigation has been laid by the accurate anatomic studies of Rioch2 (1929, 1931).
Using the Horsley-Clarke instrument and a bipolar needle electrode, we have explored the hypothalamic region millimeter by millimeter in each of twenty-two cats. These animals were observed for changes in the pupil, in the respiratory rate, in temperature and in the rate of urinary flow. They were watched also for