128 



Herring 



always present, and frequently runs up to the epithelial investment. The 

 neck of the infundibulum is narrow and its lumen small. 



The anterior lobe and epithelial investment of the nervous portion of the 

 posterior lobe are separated by the cleft, which, as a rule, persists in its 

 entirety. Occasionally the cleft is closed up to a large extent, especially in 

 its posterior part, and the two layers of epithelium are more or less fused, 

 but a space always remains between the main part of the anterior lobe and 

 the epithelial investment of the neck of the infundibulum. The main mass 

 of the anterior lobe in front of the cleft contains cells holding granules 

 which stain deeply with eosin. These granular cells are not present in the 

 epithelial investment of the posterior lobe, nor are they found in the tongue- 

 like process of the anterior lobe which runs forwards towards the optic 





Fig. 3. — Mesial sagittal section through pituitary body of an adult cat. 

 (Photograph.) Compare with tig 2. 



chiasma. The epithelial investment of the posterior lobe is well ma.rked 

 and thickened, especially round the neck of the infundibulum, where there 

 are many layers of cells. The cells are frequently arranged in groups 

 round a central lumen which contains a colloid material. These colloid 

 vesicles are for the most part small and scattered at intervals ; they are 

 especially well developed round the neck of the infundibulum and in the 

 tongue-like process, where they show a resemblance to the vesicles of the 

 thyroid gland. They are rarely found among the eosinophil cells of the 

 anterior lobe, and appear to be placed never far distant from the nervous 

 portion of the pituitary. 



Considerable variations occur in different cats in the relative size and 

 arrangement of the parts described. This is especially the case with the 

 eosinophil cells of the anterior lobe, which are sometimes continued far 

 backwards over the posterior lobe, but separated always from it by the 



