Perhaps no more striking illustration of the value of experimental medicine has ever been given than that afforded by the studies upon those glands.
The thyroid body, situated in the neck and the enlargement of which is called goitre, secretes substances which pass into the blood, and which are necessary for the growth of the body in childhood, for the development of the mind and for the nutrition of the tissues of the skin.

If, following an infectious disease, a child has wasting of this gland, or if, living in a certain district, it has a large goitre, normal development does not take place, and the child does not grow in mind or body and becomes what is called a cretin.

More than this--if in adult life the gland is completely removed, or if it wastes, a somewhat similar condition is produced, and the patient in time loses his mental powers and becomes fat and flabby--myxedematous.

It has been shown experimentally in various ways that the necessary elements of the secretion can be furnished by feeding with the gland or its extracts, and that the cretinoid or myxedematous conditions could thus be cured or prevented.
Experimental work has also demonstrated the functions of the suprarenal glands and explained the symptoms of Addison's disease, and chemists have even succeeded in making synthetically the active principle adrenalin.
There is perhaps no more fascinating story in the history of science than that of the discovery of these so-called ductless glands.

Part of its special interest is due to the fact that clinicians, surgeons, experimental physiologists, pathologists and chemists have all combined in splendid teamwork to win the victory.