268 Frederick Tilney, 



a) Cellular arrangement. The cells here are so arranged as to 

 form a large number of irregular acini and branching diverticula 

 which open into the residual lumen. 



b) Cells. The cells have a fair amount of homogeneous cytoplasm 

 which is basophilic, while the large picnotic nuclei have a basal 

 position. 



c) Vascularity. The vascularity is not conspicuous. 



2. Histological characters of the pars infundibularis (plate XVI, 

 fig. 31). 



a) Cellular arrangement. The cellular arrangement here is that 

 of dense cell masses with a very few scattered acini containing colloid 

 material. The walls of these acini are exceedingly thin, the lining 

 cells being of the low cuboidal variety. 



b) Cells. The cells in this portion have a small amount of 

 homogeneous cytoplasm which is basophilic; while the nuclei are 

 vesicular and usually centric in position. 



c) Vascularity. The vascularity is relatively limited in amount. 



3. Histolocical characters of the pars distalis (plate XVT, fig. 30). 



a) Cellular arrangement. The cells are arranged in long con- 

 voluted cords between which ramifies a rich plexus of blood spaces. 



b) Cells. The cells have a large amount of a granular cyto- 

 plasm which is acidophilic; the nuclei are small and picnotic. Some 

 large basophilic cells are also observed, forming a narrow peripheral 

 zone. 



c) Vascularity. This region has the greatest vascularity of the 

 entire epithelial portion. The vessels are generally parallel and be- 

 tween them are cords of acidophilic cells. 



Reviewing the relations of the glandular and neural portions of 

 the hypophysis in the dog, it seems difficult to escape the conclusion 

 that the so-called ''complete hypophysectomy" is impossible in this 

 animal without the attendant destruction of the floor of the third 

 ventricle. Certainly it is out of the question to remove the pars 

 infundibularis from its close adherence to the infundibulum and in- 

 fundibular process without lacerating or tearing out these parts. The 

 dangers of injury or destruction to the tuber cinereum in the attempt 



