The anatomical description of the hypothalamo-hypophysial system of the White-crowned Sparrow, Zonotrichia leucophrys gambelii, as presented in this treatise, is by no means of definitive nature. Research in this area, in our own laboratories and elsewhere, continues at such a pace and is sufficiently in flux as to preclude the possibility of definitive morphological and functional conclu sions at this time. Nevertheless, we do believe that there is now some genuinely heuristic value in a presentation of our neuroanatomical material. Most of this material is derived from the above-mentioned species which has received primary attention in our experimental investigations. In the course of our studies, it has become clear that the hypothalamo hypophysial system of birds has attained morphological differentiation and spe cialization as extensive as that of mammals. In order not to lose sight of the basic pattern of the system, comparative aspects must be brought into con sideration. With this in mind we emphasize the fundamental contributions of Huber and Crosby, Kuhlenbeck, Benoit, Assenmacher and vVingstrand. The ana tomical nomenclature of the avian hypothalamus has been critically examined and rationalized, to the extent possible, from a comparative view-point. In recent years this nomenclature has developed in such an independent and isolated manner that the confusion created can no longer be ignored. 'Ve dedicate our treatise to the memory of Professor Ernst Scharrer who originally stimulated our investigations.

Materials and Methods

The Cycles of the White-crowned Sparrow and Other Taxa of Zonotrichia
The Hypothalamo-Hypophysial System of Zonotrichia leucophrys gambelii
1. General Outline (Gross Anatomy) and Development
2. Hypothalamic Nuclei-General Considerations and Magnocellular Neurons
3. Parvocellular Tuberal Nuclei of the Hypothalamus
4. Parvocellular Nuclei of the Rostral Hypothalamus
5. Hypothalamic Tracts to the Neural Lobe (= Pars Nervosa, =Lobus Infundibularis) and to the Median Eminence
6. Structural Principles of the Median Eminence
7. Neural Structures of the Anterior and the Posterior Median Eminence
8. Further Remarks Concerning the Gomori-positive Structures in the Palisade Layer of the Median Eminence
9. Further Remarks Concerning the Tubero-Hypophysial Fiber System of the Median Eminence
10. Electron-microscopic Findings: Types of Granules in the Median Eminence
11. Ependymal and Glial Cells of the Median Eminence and the Nuclear Regions of the Basal Tuber Cinereum
Discussion
Summary
Addendum
References.