The social behaviour which is the material of psychological observation at any given time is the product of a certain genetic constitution on the one hand, and of a complex process of social, educational, familial and, to some extent, uterine environment on the other. The social behaviour of human beings cannot be subjected to direct methods of genetic analysis. The genetic psychologist may be compared to the astronomer, in so far as he has to rely on Nature to perform the experiments which he himself is unable to undertake. To the category of such experiments belongs the phenomenon of twin production. In the production of monozygotic twins Nature provides us with individuals of the same genetic constitution. Such differences as they exhibit arise uniquely from the operation of differences in the environment in which they are placed. In ordinary circumstances they share many more features of environment than any other two individuals selected at random from the population. When reared together, the extent of their dissimilarity can only throw light on such differences of nurture as may operate on members of the same family unit and of the same age. If they are reared apart, the measure of resemblance exhibited by monozygotic twins may throw light on the influence of social environment in a less restricted sense. With a sufficiently large sample of twins reared apart, a satisfactory standard of comparison for assessing the extent of resemblance due to genetic constitution, plus the effects of a common uterine environment, would be provided by the degree of resemblance existing between their foster sibs in families into which they have been adopted. Such data cannot be collected easily. As yet they do not exist in sufficient quantity to yield satisfactory conclusions.

This contribution is an attempt to express in numerical terms the value of out-patient consultation and treatment. The group of cases considered are the first 150 who presented themselves at the Psychiatric Out-Patient Department of the Swansea General Hospital, and they are consecutive and unselected. The period during which these cases came under observation for the first time extends from March, 1933, to October, 1934; and, in assessing results, the state of the patients is taken as at December 31, 1934.

In this paper an attempt has been made to ascertain the after-histories of a particular group of patients discharged from the Maudsley Hospital, namely, those for whom further institutional treatment was considered necessary, but in whose case this advice was not taken. The investigation covers a period of three years, from 1928 to 1931. At the outset it must be pointed out that the Maudsley Hospital deals exclusively with voluntary patients, who are free to leave on giving twenty-four hours' notice; in addition, no patient is certified in the hospital, but where this is considered necessary, the friends are advised as to the procedure to be followed. In the circumstances, it might be thought that the number of patients who were taken home against advice would be high; but this was not the case. In a number of cases further institutional treatment was deemed necessary on grounds of psychotherapy alone; and if these are excluded, only 90 patients remain who were considered unfit for any but institutional care, either because they were dangerous to themselves, or because they were likely to prove dangerous or at least a nuisance to others. During the period under review 3, 248 patients were admitted to hospital and 2, 282 were discharged, so that the cases dealt with in this paper constituted only 2–8% of admissions and 3.5% of discharges. Of the 90 patients, 50 were females and 40 males. The length of stay in hospital varied from one day to one year.

Kraepelin and Morel were the first to emphasize the fact that tuberculosis is more common in schizophrenics than in other psychotics. Later on, Ganter, Zalla and Bonasera confirmed this statement with the support of a wide statistical inquiry. Thus Ganter found the mortality from tuberculosis in schizophrenics to be from 46 to 67%, whilst the general mortality-rate in tuberculosis in the Prussian asylums was only 16.6%; Bonasera found the tubercular mortality-rate to be 61.7%, and Zalla 67.5% in their autopsies on schizophrenics.

In support of the theory of a toxic genesis of mental diseases arising from chronic infection, some authors have attributed a special rôle to the B. coli. As long ago as 1904 Johnsohn and Goodall (1) examined the agglutination of a series of psychotics to the B. coli. They found this reaction completely or weakly positive in 50% of their cases of insanity (mostly with a serum dilution of 1: 100), while only 15.5% of their control cases showed a positive reaction. These results were not confirmed by Puca (2). Later on Goodall, together with Barton White (3), also examined the stool flora of psychotics, and found no qualitative difference as to the coliform group between psychotics and normal persons. On the other hand, Stewart (4), in more recent experiments, claims to have found such differences; thus he emphasizes the much higher frequency of the B. para-coli and B. coli mutabile in mental patients, especially in recent cases, and the parallelism between their presence and the intensity of the symptoms. Further, he found a difference in the phenol formation in broth cultures obtained from stools-of psychotics and normal persons, the former producing on the average 0.02 to 0.03%, and the latter only 0.008 to 0.03% of phenol. This stronger production of phenol is attributed by Stewart to the high frequency of B. Morgan and other phenol-producing bacteria in psychotics. He discusses the possibility that aromatic bodies produced by these bacteria in the acid milieu of the large intestine may represent the toxic agent in mental diseases.

The influence of slight variations in the inorganic constituents of the tissue fluids on the function of the nervous system has long been the subject of physiological investigation. Thus a disturbance of the ratio Ca/Na is known to be related to the irritability of muscular tissue (1). Ca and K are antagonistic in their action on the vegetative nervous system: Ca increases the excitability of the sympathetic system, whilst K excites the parasympathetic system (2). The influence of Ca on the excitability of the central nervous system finds a clinical illustration in tetany; and, from a pathological point of view, diminution of the serum Ca is well established in certain types of this disorder.

The research described in the following monograph is the result of seven years' work. In 1926 I attempted to introduce psychological methods of treatment into the out-patient department of the First Medical Clinic of the Charité, Berlin. It soon became evident that there was a widespread demand for the application of such methods within the field of the medical clinic. In the course of years, hundreds of patients with psychoneuroses linked to organs passed through our hands. A selection of specially instructive cases is given below. Our researches were performed on patients and collaborators who readily placed themselves at our disposal for our experiments. In grateful remembrance I wish to thank my esteemed former chief, the late Geh. Med.-Rat Prof. Dr. W. His, for the interest he took in my line of work and for the support he extended to it. My work in Germany came to a sudden end in March, 1933, but thanks to the kindness of Dr. F. L. Golla I was able to continue my studies at the Central Pathological Laboratory, London. Furthermore, I owe special thanks to the Professional Committee which, by the grant of a scholarship, enabled me to continue and complete this work.