202 HAROLD J. COOPER 



the gland, nor have I found anything in the nature of cilia within 

 them. The residual lumen is frequently quite filled with a 

 granular mass not unlike the contents of many of the adjacent 

 cysts. The lumen contains no cilia, though they are common in 

 the guinea-pig, as shown by Vanderburgh ('17). 



The granular cysts stain very irregularly. The hyaline ones 

 stain more consistently with the acid dyes in the pars distalis, 

 but also take on a good tinge with many of the basic ones. The 

 granular cysts show fragments in them resembling cell particles 

 in their staining reaction, some of them even appearing connected 

 with the cells surrounding the cyst. In addition to these frag- 

 ments there may be observed small masses staining with basic 

 dyes and seemingly derived from the nuclei of broken-down cells. 

 The rest of the contents stain we'll with the acid stain. It is 

 quite possible, that since the cysts are seen in varying degrees of 

 homogeneity, that the hyaline ones represent later stages of the 

 granular ones. The hyaline cysts which are usually acidophilic 

 might then well represent an extremely fine dispersion of this 

 nuclear material with a possible slight reduction of its basophilic 

 properties during its retention in the cyst. 



In the pars infundibularis the cysts are practically always 

 hyaline, and while they can be made to take on acid stains 

 they are, nevertheless, very deeply basophilic. In the pars 

 neuralis colloid can be found distributed exactly as Herring 

 ('08) describes. In the pars neuralis it is always hyaline and 

 stains deeply acidophilic. 



Stendell remarks that it is difficult to determine how much of 

 this material consists of concentrated secretion and how much is 

 cell remains, and, although it may be observed in many varying 

 types of appearance, composition, and staining quality, that the 

 colloid is the ultimate product. 



I take pleasure in thanking Prof. F. M. MacFarland for his 

 interest and assistance which proved invaluable in the prepara- 

 tion of this paper. 



