In the present communication it is intended to consider the fundamental formula of mental excitation processes, H + L = T, in terms of seeing. The equation implies that the characters of a light stimulus L are judged through a second factor H. T is the response of the responding organ.

CLOSE co-operation between psychiatry and general medicine is advocated with renewed vigour from time to time. This is a wholly desirable thing, provided that the essential differences between disorders of the individual as a whole and disorders of his several organs are kept clearly before one.

The object of this paper is to place on record some work which has been done during the past fourteen months in the laboratories of the Cardiff City Mental Hospital. This work, which is in the nature of animal inoculation experiments, was done with a view to detecting the presence of any filter-passing organisms which might be present in cases of schizophrenia. The justification for this line of research depends upon the suggestions that have been made by American and Continental writers that there are many striking points of resemblance between epidemic encephalitis and schizophrenia. In this country, Farran-Ridge has pointed out the striking similarity of the motor phenomena in certain cases of these two conditions. He draws attention particularly to fluctuation in body-weight, blepharoclonus, pruriginous phenomena, chewing movements, greasy face, respiratory disorders and choreiform manifestations. It has been suggested that these symptoms may be due to involvement of the basal ganglia. This being so, there is primâ facie evidence that some cases of both encephalitis and schizophrenia are the outward manifestations of similar disease-processes. In the case of encephalitise, vaditi, Loewe, Hirschfield and Straus and others have done work which suggests the existence of an ultra-virus of variable virulence which may exist in the saliva, the central nervous system, herpetic vesicles and elsewhere. If, therefore, these premises are correct, it would be valid to search for a similar virus in schizophrenia.

It is a well-known axiom that to know one subject thoroughly entails more than a passing acquaintance with many others. This is especially true of the field of medicine, where neglect of any one related subject may lead to an incomplete, or even to an erroneous solution of a particular problem.

Psychology was for centuries a part of philosophy, the happy, undisputed hunting-ground of the speculative metaphysician. With the beginning of the nineteenth century a new era dawned gradually for psychology. Anatomists, physiologists and physicists began to invade this reserve of the metaphysician. These early attempts of Gall and Spurzheim, Johannes Müller, E. H. Weber, Du Bois Reymond, Helmholtz, Lotze, Fechner, Thomas Young and many others are too well known to detain us. They lead up to the work of Wilhelm Wundt and the establishment of psychology as one of the natural sciences, from speculation without facts to speculation allied with experiment. However, as usually happens, the swing of the pendulum goes from one extreme to the other. For whilst the metaphysical psychologist would ignore physiology and neurology, maintaining that what is not itself a phase of consciousness cannot be used to explain consciousness, some of the physiological psychologists would overshoot the mark and attempt a psychology without consciousness. Thus we find the behaviourists (Watson) and the objective psychologists (Bechterew). Pavlov appears to belong to the latter school. But as Prof. Brett, in his History of Psychology, rightly says: “Modern psychology lies between two points: it emerges from anatomy and physiology, and terminates in a region where those sciences cease to guide.”

It is generally known that the normal ratio between serum albumen and serum globulin is altered in general paralysis.

In recent years the approach to psychiatry has become more and more biological. The point of interest is shifting from the kind of mental illness which a person has, to the kind of person who has the illness. The greatest stimulus in this direction to psychiatry in the last few years was undoubtedly the publication, in the year 1921, of Kretschmer's Körperbau und Charakter. Indeed, the stimulus was so violent that nowadays hardly any psychiatric field (not to mention other branches of the biological sciences) has escaped exploration along Kretschmer's lines; and the vast bibliography which has piled up is enough to appal the student of constitutional biology and kindred subjects. For some reason, surprisingly little work has been done on the constitution and temperament of the weak-minded. The object of this present research is to fill the lacuna in some small measure. The neglect of this field of study is surprising, for the reason that weak-mindedness is classified by Kraepelin, the father of modern psychiatry (Psychiatrische Klinik, Barth, Leipzig, 1921, Bd. i, S. 23), in the group of the congenital mental disorders; and a congenital anomaly should surely be expected to provide interesting material for biological research. The present writer, then, approached his subject without prejudice and without a thesis. It was his business to study a group of congenitally weak-minded people, and observe and record their physical and temperamental anomalies.