For this discussion of pituitary problems, I have selected from my records of the past three years a series of eighteen consecutive cases, representing what were regarded as primary intrasellar lesions, for the relief of which a transsphenoidal hypophysectomy was performed. In this series, there were no operative fatalities. Three patients have died in the interim, and of the remaining cases the results have been satisfactory in 75 per cent. I have not included in this discussion, but will reserve for a later paper, hypophysial duct tumors, tumors of the pouch of Rathke and tumors adjacent to the pituitary but not of pituitary origin, lesions which when recognized are best approached by the transfrontal operation. The pituitary body offers an interesting theme for discussion from many angles, the more interesting perhaps because there are now and will be for years so many problems still undetermined, problems relating not only to