Von Blarer analyses the aetiological complementary series resulting in primary infantilism by means of case illustrations and employing concepts of the theory of representations. Hereditary, congenital or traumatic defects of a motor or sensory ego apparatus frequently trigger off an interaction pattern which interferes with the functional compensation of the defect; thus the child's growth to autonomy is obstructed. Retardation or arrest of development may follow. The mother (and others in the family or nursing milieu) may experience the child's defect (e.g. blindness) as a narcissistic injury and turn away in disappointment (emotional deprivation). Two other inadequate reactions are denial of the defect (the saving of the work of mourning) and overprotectiveness. The former interferes with the child's constructing a realistic self-representation; the latter results in the permanent substitution of the maternal auxiliary ego for the child's defective ego apparatus.