200 HAROLD J. COOPER 



On the upper surface they are not very well defined and, as a 

 rule, only a few gland cells are scattered along its extent. The 

 layer is closely applied to the infundibulum and consists of small 

 cells (3.5m to 4.5/z in diameter) packed close together. The 

 cytoplasm is scanty and does not stain with acidophilic stains. 

 The nuclei are hyperchromatic and a general basophilic character 

 is imparted to the cells. Just exterior to this are numerous blood- 

 vessels bounded still further exteriorly by a layer of the dura. 

 These blood-vessels are in close relation to the cells and at fre- 

 quent intervals they may be seen extending into the gland sub- 

 stance. These vessels appear to be continuous with those of 

 the pars tuberalis above. The part, as a result, is quite vascular, 

 being much more so than the portion investing the infundibular 

 process. 



b) Pars tuberalis. The pars tuberalis extends a considerable 

 distance forward (fig. 1), but is not made out posteriorly except 

 as a few scattered cells distributed along the base of the brain in 

 much the same way as the cells of the upper surface of the infun- 

 dibulum. The cells are slightly larger (6m to 8m in diameter), 

 but, like those investing the infundibulum, they have a scanty 

 cytoplasm and hyperchromatic nuclei. The most character- 

 istic feature is the tendency of the cells to arrange themselves 

 radially about a central point like a gland follicle. Such groups 

 are quite numerous, and in between them the cells are distributed 

 quite irregularly. Numerous blood-vessels are seen which seem 

 to be continuous with those of the pars infundibularis below. 



II. Pars neuralis 



Little need be said relative to this, inasmuch as the findings 

 agree very closely with those of Herring for the cat. The in- 

 fundibulum is long and slender and is invaded by the cavity of 

 the third ventricle as far as the nervous lobe. The fibers of the 

 infundibulum run for the most part longitudinally. There are 

 many which run transversely from the sides of the infundibulum 

 toward the center where they curve either upward or downward 

 along the stalk. The fibers which run toward the glandular part 



