IT is THE PREVALENT OPINION that development of the long bones and growth in general are regulated by the hormones of the anterior lobe of the hypophysis. Hence the gigantic growth in cases of actively secreting tumors of the pituitary, in contrast to the nanosomia observed in the absence of adequate function of the anterior lobe during childhood. The relationship of the thyroid gland is also definitely established. Thyroidectomy inhibits the skeletal development of juvenile animals, while retardation of growth is observed in congenital or childhood hypothyroidism in men. Whether or not a lack of thyroid hormone directly interferes with growth is not quite clear for at least part of the inhibition is attributable to changes in the pituitary followed by a decrease of its growtlhpromoting function. However, a direct effect of the thyroid on growth is probable, according to clinical experience, because pituitary substitution therapy yields better results if adequate amounts of thyroid are also given. Evidenc...