THE SUPEARENAL GLANDS 553 



are arranged in long straight columns which extend from the zona 

 glomerulosa inward to the zona reticularis. The cells are columnar or 

 polyhedral in shape ; many of them contain minute fatty droplets in great 

 abundance. This fat is readily blackened by osmic acid. Arnold (1902), 

 by extraction with ether, obtained crystals of palmatin and stearin from 

 the suprarenal gland. Plecnik (1902), however, considers that the 

 adrenal fat differs in its ultimate chemical properties from the other fat 

 of the body. Each columnar group consists of cells which are, as a rule, 

 in approximately the same stage of fatty metamorphosis, and the cell 

 columns of this zone may be divided into those which are distinctly 

 acidophil and those which are distinctly fatty, though between these 

 extremes there are many intermediate stages. 



The acidophil cells are ovoid or polyhedral elements which possess 

 one or two highly chromatic spheroidal nuclei and a finely granular 

 cytoplasm. On careful examination with high magnification, extremely 

 minute fat droplets may often be demonstrated even in the most char- 

 acteristic of these cells; with lower magnification these are frequently 

 invisible. 



The fatty cells possess a spheroidal nucleus which is usually vesicular 

 in character; occasionally it is highly chromatic. Frequently the ap- 

 parent chromatolysis seems to progress in exact ratio to the accumulation 

 of fat; those cells in which the fatty metamorphosis is more advanced 

 present the more typically vesicular nucleus. With the progress of the 

 fatty metamorphosis the cell outlines are again lost and the granular 

 acidophil cytoplasm gradually replaced. The presence of fat in the broad 

 zona fasciculata is partially responsible for the bright yellow color of 

 the cortex of the organ. 



The cells of the zona reticularis are similar to those of the zona 

 fasciculata, though the fatty metamorphosis is le*ss pronounced. In one 

 particular, however, the cells of this layer are remarkable. They con- 

 tain an abundance of a peculiar brownish-yellow pigment which occurs 

 both in the form of coarse granules and as a diffuse coloration of the 

 cytoplasm. The spherical nuclei, highly chromatic or only slightly 

 vesicular in character, are not invaded by the pigmentation. The vol- 

 ume of pigment varies greatly in different individuals; it is usually 

 absent in young persons, but is, as a rule, present after the twentieth 

 year of life (Maass, 1889). In the suprarenal of the mouse many of 

 these cells can be seen in process of amitotic division. 



The epithelial cells of the medulla are ovoid elements with one 

 or two spherical nuclei, which in many cases possess a vesicular char- 



