348 C. M. JACKSON 



however, the cytophisin tends to become more homogeneous in 

 appearance. In the eosinophiles, at least, this is apparently 

 because the stain affects the intergranular substance as well as 

 the granules of the cytoplasm (figs. 2 and 4). Sometimes the 

 cytoplasm presents a finely vacuolated appearance. Various 

 developmental stages of the 'ring-cell' type described by Addison 

 ('16) are occasionally met in rats of ten weeks or more. The 

 cell-boundaries of the acidophiles (eosinophiles) are usually dis- 

 tinct, while those of the basophiles and chromophobes are indis- 

 tinct. The various types of cells in the hypophysis of the 

 normal rat are well shown by colored figures in the second volume 

 of Biedl ('13). 



The nuclei of the chromophobic and weakly chromophilic cells 

 are spherical or ellipsoidal in form and similar in structure, pre- 

 senting a distinct nuclear membrane and an indistinct, irregular 

 nuclear reticulum with one or more distinct karyosomes (figs. 2 

 and 4). The nuclei are somewhat vesicular in type and only 

 moderately chromatic. To a certain extent, the amount of 

 chromatin appears to var^^ inversely with the age, since the 

 nuclei stain more deeply in the younger stages (up to three weeks) 

 than in the older (ten weeks or more) . 



The nuclei of the eosinophilic cells also show- a tendency to 

 more highly chromatic (deeply staining) condition, which is 

 especially marked in the strongly eosinophilic (as noted by 

 Stendell '14), as well as in the rarer strongly basophilic cells. 

 In the strongly eosinophilic cells, it was frequently noted that 

 the nuclear matrix (karyolymph) becomes acidophilic, staining 

 red like the cytoplasm. It may likewise appear purplish in 

 the strongly basophilic type. 



In a few of the strongly chromophilic cells the nuclei may in 

 extreme cases present even a pycnotic condition. This tendency 

 to pycnosis is usually more evident toward the periphery, near 

 the surface of the gland and usually involves more or less atrophy 

 of the cytoplasm. In addition to these apparently normal pyc- 

 noses, others may be observed in the region of injuries produced 

 during removal of the gland. This was found also in the thy- 

 roid gland (Jackson '!()). Pycnotic nuclei, possibly degenera- 



