With the great recent progress of anatomy we are just at the beginning here, the chief result so far being the possibility of distinguishing senile involution and its morbid traits with a view to eventually being able to make an anatomical differential diagnosis, such as we must do to really get at the root of the problem of senile dementia. From this point of view other processes can readily be derived, and some of them histologically, like regression. The anatomical investigation stands in temporal relations with the idea of senile dementia and it must be defined or widened enough to do this. Perhaps we shall be able to have a good anatomical picture of senile dementia beginning with the fifth and sixth decennium and even to explain atypical forms and show their relation with the central system. Here, then, the author, starting from an anatomical basis, begins with a study of forms that are atypical in localization, intensity, or temporal onset. Then he can discuss the mental diseases that are based on sclerosis. So he first discusses briefly those psychoses that rest upon clearly recognizable but not yet very distinctly determined brain troubles that deviate from the ordinary senile processes and those, which so far as we can now see, are really sclerotic. Then the long series of psychoses, the anatomical substratum of which we do not yet know, and the functional processes of this age can be discussed. In doing this, more than in the case of many organic processes, we shall find a great difficulty in proving for such diseases their specific senile or climacteric character. We shall constantly face the objection that we have here to do only with mental diseases that usually come in other ages and only have peculiar traits on account of the age of the patient, as is the case with many depressive and paranoiac symptom-complexes of regression that resemble those of age. Thus the distinction of regressive psychoses from senile changes, this author thinks, cannot be carried through by grouping them in the decennia in which they arise. It would be better to distinguish them as progressive and incurable, or otherwise, but this could be done only with further distinction of our anatomical and clinical data and we shall perhaps still lack that for a long time. When, therefore, in these regressions we start from anatomy and the psychoses connected with it at this age of life, we may seem to overestimate the achievements of histology. We at any rate do not underestimate our ignorance here. But with the great confusion of opinions based on clinical observations we believe we are justified in this point of departure. Ultimately anatomy will very likely be our guide in all clinical work as well as in the field of psychiatry, physiology, and psychology. We shall doubtless also learn very much more about the localization in which the degenerative processes of age begin.