WILSON, DR. McCLEOD C., appointed Clinical Assistant at Bloomingdale Asylum at White Plains, N. Y., June 26, 1906. WRIGHT, DR. WILLIAM WESLEY, of Oswego, N. Y., appointed Junior Assistant Physi cian Buffalo State Hospital at Buffalo, N. Y., September 12, 1906. YEAMAN, DR. MALCOLM H., Superintendent of the Central Kentucky Asylum for the Insane at Lakeland, resigned October 1, 1906, to take charge of Beechhurst, the Barton W. Stone Sanitarium at Louisville, Ky. YOUNG, DR. G. A., Pathologist at the Nebraska Hospital for the Insane at Lincoln, Neb., was promoted on July 12, 1906, to be Superintendent of the Hospital for the Insane at Norfolk, Neb., but owing to legal complications he has not been able to assume the duties of that office and is now acting First Assistant Physician of the Nebraska Hospital for Insane at Lincoln, Neb. Announcement of College of Physicians and Surgeons of Baltimore, 1906-7. The Journal of Prison Discipline and Philanthropy. January, 1906. Published annually by the Pennsylvania Prison Society. Annual Announcement and Catalogue of the Baltimore Medical College, Baltimore, Md., Session 1906-7. Thirteenth Annual Report of the Managers of the Middletown State Homœopathic Hospital at Middletown, N. Y., to the State Commission in Lunacy for the year ending September 30, 1905. Superintendent's Biennial Report of the Iowa State Industrial School for Girls at Mitchellville, to the Board of Control of State Institutions for the period ending June 30, 1905. Twenty-third Biennial Report of the Mount Pleasant State Hospital, and the Second Biennial Report of the Hospital for Inebriates at Mount Pleasant, to the Board of Control of State Institutions for the period ending June 30, 1905. Warden's Biennial Report of the Penitentiary at Fort Madison, Iowa, to the Board of Control of State Institutions, for the period ending June 30, 1905. Biennial Report of the Superintendent of the Iowa College for the Blind at Vinton to the Board of Control of State Institutions, June 30, 1905. The Seventeenth Biennial Report of the Warden of the Penitentiary at Anamosa, to the Board of Control of State Institutions for the period ending June 30, 1905. Biennial Report of the Superintendent of the Clarinda State Hospital at Clarinda, Iowa, June 30, 1906. Twenty-first Biennial Report of the Superintendent F. F. Sessions, of the Iowa Soldiers' Orphans Home, at Davenport, June 30, 1905. Seventeenth Biennial Report of the Superintendent of the Iowa State Hospital for the Insane at Independence, to the Board of Control of State Institutions for the period ending June 30, 1905. Twenty-sixth Biennial Report of the Superintendent of the Iowa School for the Deaf at Council Bluffs, to the Board of Control of State Institutions for the period ending June 30, 1905. Bulletin of the University of Nebraska, College of Medicine. Vol. 1, No. 3, July, 1906. I. The Microscope in Its Relation to Medicine. James Carroll, M. D. II. A Study of Filtration in the Lung of the Frog. A. E. Guenther, M. D. Bulletin No. 109 of the Maryland Agricultural Experiment Station, College Park, Md., May, 1906. Sur les Simulateurs. Clément Charpentier. Extrait Des Actes du VI Congrès International d'Anthropologie Criminelle, Turin. 1006. Quelques Temps De Reaction Chez Les Aliénés. Clément Charpentier. Extrait Journal de Psychologie Normale et Pathologique, Mai-Juin, 1906. AMERICAN JOURNAL OF INSANITY THE EMBRYONIC PIA. BY CLARENCE B. FARRAR, Assistant Physician and Director of the Laboratory, Sheppard-Pratt The encephalon is essentially an ectodermal organ, being derived from the epiblast in the developing embryo. Very early, however, practically as soon as the cerebral vesicle appears and the hemispheres become differentiated, the ectodermal organ is surrounded by a mesodermal sheath, from which arise later the two membranes,-the dura and the pia-arachnoid. This development and differentiation can be well followed by examining a cross-section of the cord region in an early embryonic chick. As soon as the medullary ridges are formed and begin extending dorsally, the underlying mesoblast pushes into them, and when they finally coalesce to form the neural tube, the latter is completely surrounded by a mesoblastic layer, shutting it off from its original connection with the superficial epiblast which goes to the formation of the integumental structures. This enclosing mesoblastic sheath is continuous in front with the common mesoblast which gives rise to the vascular, muscular, and other mesodermal systems, but becomes narrow as it follows the neural tube dorsally, and at the point of closure of the latter presents as a delicate membrane-like structure. Reference to the accompanying schemata will recall clearly these relations. (Plate VI.) The innermost portion of this mesoblastic sheath lying adjacent to the neural tube enters at once into the formation of the rudimentary pia-arachnoid, all of whose constituent elements are derivatives of a single cell-type, the branching embryonic connective-tissue cell. Following the law of adaptation by which cells, which through accident of position or by reason of inherent geotropic tendencies come to possess particular relationships, at once assume more or less specific and characteristic morphologic if not chemical peculiarities, the earliest differentiation within the embryonic pia-arachnoid is observed to take place among the elements of the sheath nearest the neural tube. These assume the spindle-form and arrange themselves end to end to form the membrana limitans meningea interna, to which still remain attached the anastomosing processes of adjacent mesoblastic cells. This embryonic limiting membrane may be regarded as a differentiated product of cell protoplasm,-a katabiotic product in WEIGERT'S sense. In the cells contributing to its formation regressive changes are not infrequently demonstrable. Very soon the connective-tissue cells of the inner zone of the mesoblastic sheath are seen to be disposing themselves so as to form wide round, oval or elongated spaces,-the primitive bloodchannels of the pia-arachnoid, which may soon become so numerous as to form an almost unbroken chain of wide lumina occupying the inner portion of this membrane, adjacent to the epiblastic layer of the neural tube or cerebral hemispheres. (Plate VIII.) These rudimentary blood-channels differ very little from the remaining cavities in the arachnoid mesh, their boundaries being merely a little more regular and better defined by reason of more elements taking part in their formation than is the case with the arachnoid spaces. (The term arachnoid is here used simply as a descriptive adjective to indicate the web-like structure of the mesodermal mesh, and not to designate a separate membrane or any part particularly of the enclosing mesodermal sheath.) The rudimentary vessel walls are represented at first by a single layer of cells, and these maintain all the characteristics of the surrounding stroma-cells, with which their processes anastomose freely. (Plate IX.) As soon as the lumina are closed, erythrocytes appear within them, displaying many nucleated forms. From the chain of dilated lumina running along the inner boundary of the pia, perpendicular off-shoots soon appear and penetrate the underlying nervous parenchyma. These vascular cavities likewise consist of wide channels, whose walls are formed by a single layer of connective tissue cells, which gradually change somewhat their character to suit their new environment and func tion, and are henceforth to be known as endothelial cells. Mitoses are frequent both in the stroma-cells of the pia-arachnoid, and in the mural elements of the rudimentary vessels. While these alterations are going on in the inner zone of the enclosing arachnoidal sheath, changes of a different nature are taking place in its outer layers; so that very early three lamina with morphologically distinct characters are differentiated, the middle one of which alone still presents the primitive features of the mesoblastic sheath. While lumina are being formed in such numbers in the inner zone, a few are laid down at irregular intervals throughout the middle zone, although here by no means so numerous, while more externally the connective-tissue elements are assuming elongated forms and crowding together with long axes parallel, giving rise to a very close mesh with long but extremely narrow spaces, in contradistinction to the loose irregular reticulum of the pia-arachnoid. From this external layer comes the primitive dura, which is soon separated from the pia-arachnoid by a fairly sharp line of demarkation, and in many places by a narrow clear zone. (Plate VIII.) Thus the inner portion of the mesoblastic sheath is early divided into two layers, an outer one, which becomes the dura, and is poorly vascularised, and an inner one, which becomes the richly vascular pia-arachnoid. In the thickness of the latter, however, no separating line can be drawn subdividing it into two membranes. The pia-arachnoid then from a developmental viewpoint, is a single membrane consisting of a loose reticulum, the trabeculæ of which are formed by the branching and anastomosing processes of connective-tissue cells. At the outer and inner borders these cells tend to arrange themselves horizontally to form limiting membranes. The blood-vessels, which owe their origin to the same elements, are situated for the most part, but by no means exclusively, along the inner border of the membrane. In places where the space between the dura and pia has not yet become established, the unity of the elements composing both membranes is very apparent, and their cell processes anastomose freely, the elements of both showing characters essentially similar, those in the external portion which is to become the dura, appearing merely somewhat more spindle-shaped, while those within maintain a stellate form. In other places where a cleft |