Abstract
THE SERIES under investigation comprised 103 patients with mental deficiency from birth to 55 years of age. On most of these a complete autopsy was performed. The diagnoses of the cerebral lesions causing the mental deficiency were based on the autopsy observations, in addition to the clinical findings and the history. In the table, 87 cases in which microscopic material was available are summarized, with their etiologic origins shown in column 4. The statements in the table are of necessity brief and reveal little of the wealth of interesting information on which many of them are founded. They do demonstrate, however, that the series was quite heterogeneous with respect to the injury to the nervous system. In addition, the autopsy reports showed that there was no uniformity with regard to the extent of the lesions. In some patients a completely cystic brain weighing a few hundred grams was observed; in