The author advances the concept that anoxemia, either in its general or restricted form, or both, is probably responsible for a considerable portion of "degenerative diseases," whose etiologic delineation has not yet been traced. It is necessary, he believes, to enlarge greatly the comprehension of the disordered circulatory states to include oxygen want and thereby account for a number of conditions hitherto considered to be of unknown cause. More than this, he finds in oxygen want an explanation of the mechanism of a number of individual lesions or details of lesions otherwise not well understood. The author believes it is very likely that an understanding of cerebral anoxia in its ultimate ramifications will open still wider doors to the understanding of certain clinical syndromes the cause of which remains obscure.