the other ductless glands (the spleen, the thymus, and the adrenal bodies), is but imperfectly understood. I shall limit myself to saying that the presence of the normal thyroid gland is necessary for health, and that it is supposed that the secretion of the gland, which enters the blood-current directly, either neutralizes some poison which, from the ordinary processes of life, is circulating in the blood, or furnishes to the blood some substance which is necessary to it. When from any cause this function of the gland is interfered with, very characteristic symptoms result. It is only within recent years that it has been recognized that impairment of thyroid function can and does cause a definite group of symptoms which constitute a disease. These symptoms may occur when a tumor develops in the gland, and will be intensified if, when the tumor is removed, much of the gland substance is destroyed.
But the most important disease of the gland itself, which is insidious, chronic, and progressive, is myxœdema. This affection is a chronic inflammation of the thyroid gland, by which the secreting structure is gradually destroyed, and which consequently deprives the patient of the good services which are rendered by a normal gland. In many respects myxœdema resembles Bright's disease, and it was some time after the first description of it by Sir William Gull before it became established that the affection depended upon the impairment of function of the thyroid gland, and not upon disease of the kidney. The most prominent symptom of the disease, and the one from which the name is in part derived, is an œdema or swelling, which, unlike the œdema of Bright's disease, does not pit on pressure. This œdema is most prominent in the face, and it is there that it begins, although later in the disease it may extend to the hands and feet, and thereby increase the general weight of the body. The lips are thickened, the nose becomes large and flat, and the eyelids are swollen. Owing to the swelling of the tongue and throat, the character of the voice may be changed. The skin is dry, rough, and peculiarly pale; the hair falls out—a symptom particularly noticeable in the eyebrows—the teeth become poor and the nails brittle. The pulse is slow, the heart is weak, and the temperature is almost always below the normal. Neuralgic pains are of common occurrence in myxœdematous patients, and cold weather is very disagreeable to them, probably on account of their low body temperature. The muscles are weak, especially those of the head and neck, and all muscular movements are slowly performed. The mind becomes dull and apathetic; there is usually developed irritability of temper. Hallucinations or perverted sense perceptions are not at all uncommon, and occasionally the affection terminates in insanity. These patients are peculiarly sensitive
