594 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



The physiological role we have ascribed to neuroglia-cells and 

 fibers further emphasizes the importance of these structures 

 and of the marked nutritional activity of which they are the 

 seat. As a complement of this we showed that Andriezen traced 

 a direct nervous connection in all classes of vertebrates between 

 the "posterior lobe of the pituitary," on the one hand, and 

 "the olfactory center" and the "bulbo-spinal centers," on the 

 other. 



When these facts and others reviewed are placed side by 

 side with the adduced evidence (1) that the middle brain is the 

 seat of a nervous mechanism through which highly differen- 



TRANSVERSB VERTICAL, SECTION OF THE INFUNDIBULAR REGION. 

 a, Lumen of ventricle, a', Lumen of infundibulum. 1, Primary forms of 

 ependymal neuroglia, the processes extending from a cell-like body at the edge 

 of the ventricular cavity to the subpial limit. 2, Coarser and less ramified 

 variety of ependymal cell. 3, Coarser ependymal cells, branching within the 

 inner half of the infundibular wall. 4, Portions of ependymal cells with tufted 

 subpial branchings. 5, Unstained nerve-cells. 6, Pyramidal cells with long, fine 

 processes. 8, Transversely lying cells of small size with knobbed extremities. 

 9, Pyramidal cells with large numbers of apical processes. 10, Probable axis- 

 cylinder extension of pyramidal cells with thickenings, and rectangular exten- 

 sions to the subpial limit. 11, Nerve-fibers passing from the infundibular wall 

 into the tissues along the border of the ventricle. 12, Burr-like cells of the 

 infundibular wall. 13, Line of the floor of the brain. 14, Long-rayed ependymal 

 cells of the juncture of the ventricular and infundibular cavities. 15, 15, Fir-tree 

 ependymal cells of various sizes and forms lining the border of the ventricle. A 

 few of them are seen to have rounded knobs adjusted against the pial limit of 

 the basis cerebri. 16, Neuroglia cell approximating the short-rayed type of Golgi. 

 17, 17, Sustentacular glia-cells of the inferior border of the tuber cinereum. 18, 

 19, Glia-cells with numerous long and stout hairy processes from the bodies, and 

 thicker projections, probably transition forms between the sustentacular cells and 

 cells of later development. 20, Probable nerve-cell resembling some of the glia- 

 cells. 21, 21, Large mossy cells situated at some distance from the ventricular 

 border. 22, 22, Nerve-cells of different forms. (Berkley.) 



tiated afferent impulses meet with response, and (2) that the 

 structures to which Berkley and Andriezen refer are contained 

 precisely in the central gray matter which Foster considers as 

 "perhaps in point of origin the oldest part of the brain" and 

 which "seems to serve chiefly as a bed for the development of 

 the nuclei of the cranial nerves," it seems clear to us that the 

 posterior pituitary body is a general center in which active func- 

 tions are incited and governed in response to afferent impulses. 

 A neuron, we have seen, presents all the attributes of other 

 organs; that the analogy includes the functional limits of these 

 organs is very probable. Under these circumstances and taking 



