in man and in certain animals as composed in early life of three distinct physiological entities-the medulla, the cortex, and the androgenic tissue. The last named term has been coined to describe that portion of the adrenal which, in certain pathological conditions, gives rise to disorders of the reproductive system. This view of the tripartite nature of the adrenal is supported by many well-established facts. It affords a rational explanation of the relation of the adrenals to certain pathological conditions of the reproductive system and avoids assuming a relation between the cortex proper and the sex glands as previous writers have unjustifiably done.Many of the views expressed in the present volume are based on the results of experimental studies in which my colleagues, to whom I am deeply indebted, have collaborated. Dr. Warfield M. Firor has performed surgical operations and enthusiastically cooperated in these researches; Dr. Evelyn Howard is jointly responsible for the studies dealing with the relation of the adrenals to the reproductive system; and Mr. Ellis Grollman has aided in the preparation of the adrenal extracts.I wish also to express my sincere appreciation to the publishers for their cooperation and unfailing courtesies.A. G. Baltimore, Maryland. * Superior figures refer to the numbered entries of the bibliography. For the literature before 1850, the reader is referred to the excellent historical reviews of Biedl 66 and Shumacker. 6661' 1 ANATOMY early state of differentiation is in reality due to the presence of epinephrine is demonstrated by the inhibition of intestinal movements by extracts of this tissue. 317 • 669 ACCESSORY ADRENAL BODIES The tissues of the adrenals are not confined to that which occurs in the main glands. As we have already seen, the medullary tissue is only one part of a widely distributed chromaphil system. The cortical tissue is also composed of several masses of glandular tissue located at a considerable distance from the main gland. Previous writers have considered all of this tissue, because of a similarity in its gross histological appearance, as being functionally part of the same tissue.This view, however, is not supported by physiological or pathological findings and we shall, therefore, classify the cortical (or interrenal tissue) into two groups: 1) the true cortical tissue and 2) the androgenic tissue. The cortical tissue proper elaborates a hormone essential for life. It forms the outer layers of the adrenal gland and occurs at times as accessory adrenal bodies in the near vicinity of the adrenal.A second part of the cortical tissue, resembling the first histologically in many respects, occurs as the internal layer of the cortex in certain animals during the early period of development, but soon disappears (except under some pathological conditions).This tissue also appears in the form of temporary accessory bodies which are widely distributed. The second type of cortical tissue shall be designated as the androgenic tissue because of its masculinizing effect...