In the large group of psychoneurotic patients, the main emphasis has not to be laid upon the same factors in all the cases. In some cases the disorder of a somatic system plays an important etiological rôle; in some cases there are definite emotional idiosyncrasies; in some patients special experiences have sensitized the patient in certain directions; in some there has been, even with fair equipment and with no obvious disorder of the simple emotional reactions, a balance impossible to maintain for an indefinite period. In some there are personal traits of very special nature which cannot be reduced to simpler elements. In the formulation of each case one must take into account the possibility of a disorder at each of many levels. In working at this large group of patients we still require very much more information as to the rôle played by the simple organic functions, while not neglecting the complicated development of elaborate psychological reactions. The detailed analysis of the special determination of the specific psychological reactions has been carried further than the other lines of investigation, owing to the enthusiasm of the psychoanalytic school. There remains much work to be done in regard to the rôle of the various systems (cardio-vascular, gastro-intestinal, etc.) in the setting of the emotional reactions; and the study of the personality along lines analogous to those suggested by Hoch and Amsden is an important field for further research.