194 HAROLD J. COOPER 



obtain in the alveoli, they being about equally distributed. This 

 is just contrary to what is to be seen in the human hypophysis, 

 in which the elements are usually quite distinct, the chromo- 

 philes occupying the periphery of the alveolus, but coincides 

 more with Dostoiewsky's statement that such an arrangement 

 is not to be observed, as a rule, in small animals. The chromo- 

 philes may be either acidophile or basophile, and the existence 

 of a peripheral granular zone, described by some writers, is not 

 to be found in this gland. The chromophile cells in the pars 

 distalis are acidophilic, as a rule, when filled with granules, while 

 in the pars juxtaneuralis the cells are exclusively basophile. 



The cells of the pars distalis bordering on the residual lumen 

 are somewhat pyramidal (triangular in section) and, filling up 

 the angular spaces between the oval and polyhedral cells imme- 

 diately beneath them, they present a smooth and regular free 

 surface. Some of the spaces referred to are filled in by irregular 

 cells. These have round nuclei, while those of the pyramidal 

 cells are oval. The chromatin in their nuclei, as seen with thionin 

 stain, appears to be more diffuse than in the others, in which it 

 is often seen massed in one or more clumps. The nuclei of the 

 border cells, on the whole, stain deeply and are very numerous, 

 appearing, especially under low magnification, as one continuous 

 row. The shape of these cells seems to conform to the arrange- 

 ment of the underlying layers. Quite often the border cells give 

 the appearance of a continuous layer of low cuboidal or flattened 

 cells (fig. 4, A). The cells are not, however, of this nature. This 

 appearance of the border cells is best seen in the peripheral por- 

 tions of the cleft. The cells stain deeply and can easily be dis- 

 tinguished from the paler underlying ones. They are joined end 

 to end, but a distinct peripheral border is discernible for each of 

 them. The nuclei stain deeply and the cytoplasm takes on a 

 dark tint in ordinary staining. In other regions along the cleft 

 the cells appear wedged in between the gland cells and show the 

 arrangement in figure 4, B. 



The cells vary considerably in size, ranging from 4/z to 6^ 

 in diameter among the chromophobes having a measurable 

 periphery, to 6^ to 12^ among the chromophiles. As a rule, the 



