HYPOPHYSIS CEREBRI OF CALIFORNIA GROUND-SQUIRREL 189 



and in some cases being continuous with the lining of the cysts. 

 On the other hand, Herring states that there are none in the cat, 

 and Stendell regards their presence as extremely improbable. 



Comparatively little attention has been paid to mitoses, in 

 the adult gland at least, in which, to be sure, they are rarely 

 seen. Jackson ('17), working on albino rats during inanition, 

 gives an account of the disappearance and reappearance of mitoses 

 during and after this condition. 



Numerous slight differences have been described in the nuclei, 

 but they seem to possess no radical variations from the usual 

 forms in similar organs and tissues. Stendell calls attention to 

 the possibility that the irregularity of outline in the nuclei, 

 found occasionally in the deeply chromophilic cells, may be due 

 to intercellular pressure. 



MATERIAL AND METHODS 



The striking lack of information upon the Sciuridae in the 

 literature on the hypophysis led me to make some studies of this 

 abundant material, and results secured seem to warrant publica- 

 tion in their present form. The common ground-squirrel T 

 Citellus beechyi (Richardson), was used. The animals were 

 obtained by shooting. They were at once dissected carefully, 

 the hypophyses removed and placed in the fixative, .care being 

 taken to reject any of those that showed any damage to the skull 

 or brain in the region of the organ. As fixatives, saturated cor- 

 rosive sublimate in 70 per cent alcohol, Zenkerformol, 10 per 

 cent formalin, strong Flemming's solution, Bouin's fluid, and 100 

 per cent alcohol were used. Delafield's hematoxylin was used 

 throughout as a nuclear stain. Orange G and acid fuchsin 

 mixture (Scaffidi), chromotrope 2R and 2B were used as counter- 

 stains. Alcoholic eosin was not very satisfactory. Mallory's 

 connective-tissue stain was also used, while methyl violet, 

 methylene blue, Wright's blood stain, thionin, and other basic 

 and mixed stains were found invaluable. 



Sections were cut in celloidin and paraffin, the latter in series 

 of 5 p. The former method was employed when large portions of 

 brain and bone tissue were to be included in the sections. 



