[Hypothyroidism].

were given 0-1% propylthiouracil (PTU) in drinking water, and their offspring were examined. They were found to be practically deaf, and to have serious abnormalities in the inner ear. Addition of thyroxine to the drinking water containing PTU resulted in normal hearing and a normal inner ear, showing that the abnormalities were not caused by PTU as such, but were the consequence ofits inhibitory effect on thyroid function. It is, therefore, highly probable that in Pendred's syndrome and other similar conditions the loss of hearing is secondary to hypothyroidism during fetal life. Suggestions are put forward for mitigating the expressions of these syndromes by treatment with thyroxine during certain stages of development.