The author gives a detailed account of the Freudian theory of the anxiety-neuroses. He assumes that in anxiety-states the vaso-vegetative mid-brain apparatus is involved and, to some extent, the region surrounding the third ventricle, and connects this with the fact that the centres for sexuality are situated in the same region. In encephalitic patients anxietystates may be observed in which the clinical picture cannot be distinguished from that of anxiety-neurosis. 'We must suppose that these cerebral regions which in neurosis are affected by converted sexual excitation may at times also be injured by a physical process'.