In summarizing the findings of this paper it may be said that degenerative changes have been noted in practically every parenchymatous organ. Among these the most striking has been that of serous imbibition by the most active cells of these organs. In regard to the changes in the glands of internal secretion, the findings corroborate the statements of Cushing in regard to hypophysectomy, that removal of one gland of internal secretion results in changes in all the other glands. In this case, degenerative changes predominate in the hypophysis, thymus, ovary, and testis, while hyperplasia is seen in the islands of Langerhans and the medullas of the adrenal glands. Finally, in the rabbit athyroidism is responsible for grave degenerative changes in practically all organs and tissues of the body, and many of the symptoms of cretinism have an anatomical basis in organic cellular changes.