It has been demonstrated by one of us (L. A.),1in part in collaboration with Wu,2that among the postmortem changes presented by the central nervous system of patients who had suffered from severe gastro-intestinal infections, such as dysentery, cholera and intestinal tuberculosis, there is, in addition to the evidence of circulatory disturbance indication of a diffuse physicochemical alteration of the brain bulk, which is associated with, and is probably the underlying cause of, certain structural changes. Our main observations concerning this point were: (1) pseudoatrophy; (2) alteration of the water-binding capacity of the brain tissue, as expressed by the rate of swelling in various solutions of sodium chloride, acid and alkali and by swelling or shrinkage in fixation fluid, and (3) a peculiar change in the response of the tissue to silver salts. The last had already been observed by other authors, who interpreted it as analogous