We report in this paper a number of observations in children who very early in life, possibly from birth, showed unusual sensitivities. The general development of these children deviated greatly from normal

lines; 4 of 5 described cases could be diagnosed as childhood psychoses. We attempt to understand the observed phenomena with the aid of Freud's concept of the "protective barrier against stimuli" (Reizschutz). An organism insufficiently protected against stimuli by a "thin" barrier may need to precociously develop some ego functions. These ego rudiments appear to break down under the impact of early traumata. The paper indicates a number of questions that might be answered by future research.