A survey of the biochemical work in this field reveals a confusion of results. The lack of agreement among investigators may result from any one or more of a variety of uncontrolled factors. Differences in psychiatric diagnosis, poor research technique, including inadequate sampling and the lack of adequate normal control groups, lack of refinement in the biochemical techniques as well as lack of precision in the biochemical technicians, inadequate standards to indicate where the normal leaves off and the pathological begins, and insufficient or inept statistical treatment of the obtained data have all been more or less influential in presenting distorted and unreliable biochemical pictures of the mental disorders. These factors are in some measure within the control of the experimenter.Another factor over which the experimenter has no control and which is not a negligible one in explaining the variety and abundance of conflicting results is the variability of the psychoneurotic. The variability is uncontrolled and may yield high normal results oné day and low normal results the next in the same individual. A vegetative and vasomotor instability is probably a more or less constant symptom of neurotic behavior. The variability of the results of chemical studies of the blood appears to reflect the instability of the intermediary metabolism of the psychoneurotic. Hence the degree or kind of emotional stability may be a function of the amount of variability in the blood constituents. In the final analysis the variability of the psychoneurotic probably implies fatigue and over or under correction or loss of adaptability, which ultimately results in irritability, dysfunction and irreversibility of certain organic mechanisms.