The following conclusions may be drawn from the experiments presented in this article.
1. Excessive meat diet develops hypertrophy of the thyroid gland. A definite hypertrophy of the parathyroid gland under the same conditions has not been established. A meat diet does not develop hypertrophy of the thyroid gland when insufficiency of the parathyroid gland exists at the same time, even if no clinical symptoms are present. Where a pronounced hypertrophy caused by a meat diet has already developed, the hypertrophy disappears and the gland assumes its ordinary appearance after extirpation of a sufficiently large number of parathyroid glands.
2. After parathyroidectomy no hypertrophy of the thyroid gland takes place. In chronic tetany the thyroid gland seems, on the contrary, to atrophy in spite of a meat diet.
3. After complete extirpation of the thyroid gland, the parathyroid gland does not change its structure, even in cases where the cachexia lasts for several years. Small remaining parts of the thyroid gland may through hypertrophy develop into compact tissue and thereby seemingly present some points of resemblance to the parathyroid gland.
4. When the parathyroid gland hypertrophies, as in some forms of chronic tetany, this hypertrophy is characterized by the development of large, transparent, sharply defined cells, with large nuclei rich in chromatin.
5. The parathyroid and thyroid glands are independent organs, each having specific functions. This, however, does not exclude the occurrence of a direct or indirect interaction in the functions of the two systems.
6. There is reason to believe that an insufficiency of the parathyroid gland checks to some extent the function of the thyroid gland. No proof of the existence of a vicarious cooperation between the two glands has been established.