The presence of isolated glandular bodies in the neighborhood of the thyreoid gland has long been known. Up to the year 1888 all such bodies were described as accessory thyreoid glands, or as masses of lymphadenoid tissue. By accessory thyreoid glands are to be designated nodules of thyreoid tissue which at some time of development became separated from the main part of the gland, but still appear to be structurally similar to it. The accessory thyreoid glands are inconstant as to occurrence, and are marked by great uncertainty as to position. They have been found at all levels, from the superior hyoid region to the aortic arch.
The parathyreoid gland is a term applied to independent structures remarkably constant in number and position, which at no stage correspond in structure to the thyreoid gland, and which appear to have a function of their own.
These structures, although in all probability