132 Herring 



the brain. The cleft is rudimentary and may be almost completely closed, 

 though great differences in this respect occur in difterent individuals. The 

 pituitary of the monkey closely resembles that of man. The reactions to 

 certain staining reagents, such as hsematoxylin and eosin, differentiate it 

 into three parts : an anterior glandular, which constitutes the bulk of the 

 epithelial lobe and which contains eosinophil cells ; a posterior lobe of 

 nervous origin; and an intermediate portion (Edinger (9)), which is 

 composed of epithelial cells closely investing the nervous portion. The 

 intermediate portion, although derived from the same source as the main 

 anterior lobe, differs from it in adult mammals in that it contains no 

 eosinophil cells, and may exhibit the presence of vesicles resembling the 

 colloid vesicles of the thyroid gland. The pituitary bodies of the ox, pig, 

 and rabbit, also belong to the third type. Traces of a central cavity are 

 sometimes found in the neck of the posterior lobe, but in general the 

 pituitary bodies of these animals conform to the type illustrated in fig. 5. 



Structure of the Anterior Lobe. 



The anterior or glandular lobe as seen from below when attached to 

 the brain is the more prominent portion of the pituitary body, surrounding, 

 as it does, a large part of the posterior lobe ; it also makes up the greater 

 bulk of the organ. For the sake of description, however, it is convenient 

 to consider as the anterior lobe only that portion of it which has already 

 been distinguished from the " pars intermedia." The part thus designated 

 as the anterior lobe is separated by the cleft and by the pars intermedia 

 from the nervous portion of the pituitary. It is continuous with the 

 epithelium of the pars intermedia above in the region of the neck of the 

 infundibulum, and behind with the thin layer of epithelium which passes 

 backwards to be reflected on to the body of the posterior lobe. It is a 

 solid structure made up of columns of cells separated from one another by 

 large and numerous blood-vessels and a small amount of connective tissue. 

 The distinguishing histological feature of this lobe is the presence in it of 

 two main kinds of cells, one of which has a marked affinity for certain 

 staining reagents. 



The occurrence of two kinds of cells in the anterior lobe of the pitui- 

 tary was recognised by Hannover (15) in 1844, but little attention 

 was bestowed upon them until the researches of Flesch (10) and 

 Dostoiewsky (7), appearing independently of one another in 1884, 

 definitely established their existence. Both Flesch and Dostoiewsky 

 described one kind of cell possessing a large, round, or polyhedral bod}' 

 full of big granules, which retain a deep red colour when treated with 

 eosin and hsematoxylin, and differentiated in alcohol. These cells are 

 called "chromophil" cells by Flesch. Lothringer (22) states that they 

 are probably identical with the " Mutterzellen " of Luschka. The other 



