502 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



organ can accumulate. Capsule and protoplasmic extensions 

 or processes all serve a similar purpose, but the neck of the 

 organ is its own functional limit. 



We must not lose sight of the fact, however, that other 

 nerves penetrate the organ. Berkley says, in this connection: 

 "while, on the other hand, the nerve-fibers accompanying the 

 larger arteries are sometimes distinctly seen coming from the 

 infundibular tract into the body of the posterior lobe of the 

 gland and ramifying through it." That there is no connection 

 between these and the nervous structures previously described, 

 however, is shown by the additional statement: "Connections 

 between the fibers of the vascular supply and the nerve-cells 

 of the organ we have never been able to observe. That these 

 are the nerves through which the organ receives its own func- 

 tional energy i.e., the impulses to its vessels and alveoli, 

 as in the case of other organs, is probable." 



The prevailing view that the embryonal supporting sub- 

 stance of the brain and spinal cord, the ependymal neuroglia, 

 almost entirely atrophies and disappears in the adult mammal 

 would tend to counteract our belief that the capsule and its 

 underlying structures are important factors of the posterior 

 lobe's functions. Berkley, alluding to the writings of various 

 observers in this connection, and referring to the infundibulum 

 and other tissues of the third ventricle which he had just 

 described, says: "After reading these statements, it was some- 

 thing of a surprise to find the above-described beautiful spec- 

 imens of several types of ependymal neuroglia extending from 

 all portions of the middle and inferior regions of fhe cavity of 

 the third ventricle and reaching to the periphery, all portions, 

 bodies, branches, tentacles, and subpial endings being readily 

 distinguishable. The region examined is, therefore, very in- 

 teresting not only from the great variety of neuroglia-cells 

 that may be seen within a very limited area, but from the 

 fact that varieties of the ependymal neuroglia-cells, previously 

 supposed to have entirely disappeared from the central nervous 

 system in the adult mammal, are found present in perfect con- 

 dition in the brain of a very high order of animal, and are not 

 confined, as has previously been supposed, to those of adult reptiles, 

 amphibia, and fishes" 



