Symptoms attributed to dysfunction of the ductless glands have long been noticed in the group of mental disorders formerly known as dementia praecox, now included in the wider designation schizophrenia. A variety of such abnormalities has been described, but without sufficient consistency or clarity to help in formulating a pathology of the disorder. From the first, the usual onset in adolescence or early adulthood, and the symptomatology, prompted investigation of the gonads. Papers have been published by Fränkel (1919), Mott (1919), Pézard (1920), Tiffany (1921), Lewis (1923), Morse (1923), Geller (1923), Münzer (1926), McCartney (1929), in which histological changes in the testis in schizophrenia are cited and discussed. The contributions of Mott, Lewis and Morse are the most important, for their material and histology are more accurately controlled and described. It appeared as if the very extensive work done by Mott had succeeded in establishing a direct relationship between gonadal failure and dementia praecox. Subsequently his findings were heavily criticised and the conclusions to a great extent rejected, for, like others, he had obtained material at post mortem, mostly from patients who had died of tuberculosis or other diseases liable to produce the very changes he regarded as specific; very few were young adults in the early phases of the mental disease. These objections constituted an apparently insuperable difficulty, and the whole question has remained virtually in abeyance ever since.