The Thyroid Secretion, when lessened or absent, gives rise to the condition known as myxedema. In this the skin becomes much swollen and firm, particularly in the region of the face. The skin will not pit on pressure nor are the dependent portions affected. The hair frequently falls out, the voice undergoes changes, and there are commonly decided disturbances of mentality. If sheep's thyroid gland is given in such cases there is frequently a decided improvement.