In the course of toxic and febrile processes, such as occur in association with typhoid, erysipelas, malaria, pneumonia, influenza, psychoses may arise. Amongst the infection-psychoses may be counted also the insanity of the puerperium. In association with epidemic encephalitis various psychoses develop—a fact of significance in the problems of the pathogenesis of these states. Of peculiar interest is the occurrence of disorders of motility in the course of, and after, this disease, resembling muscular disorders in katalepsy and katatonia. A recent and valuable addition to the literature of this subject is furnished in an article by Skliar, who has had the unusual experience of seeing mental disturbances in the course of typhus and relapsing fever, prevalent in Russia during the three winters 1918–1920, inclusive. He also describes five cases of Lyssa in which psychotic disturbances occurred.

It is extremely befitting that this Association should be interested in the relation of chronic sepsis to mental disorders, principally for the reason that this idea had its origin in England. As early as 1875, Savage, the English alienist, reported the recovery of cases of mental disorder following the extraction of infected teeth. The full significance of this report, of course, was not realised at the time, for if it had been recognised, an entirely different history of the care and treatment of mental disorders during the last century would have been written.

It is interesting to recall that fifty-five years ago Maudsley wrote as follows:

As students of psychiatry we must remember that the human being is merely a biological unit always to be studied and considered by the quality of its reaction to the environmental impositions made upon it by the social body to which it belongs.

In this lecture it is my intention to illustrate the usefulness of the psychological conception of psychical disturbances by saying some thing about the psychology of epilepsy.

In dealing with the surface tension peculiarities of the anxiety states I will only dwell very shortly on the physical aspects of the problem. If two bodies are brought into proximity, then each body attracts the other with a force which was shown by Mitchell and Cavendish to be identical with the force of gravity.