352 SECRETION. 



ject ; * but it is probably the fact that the rows of cells are 

 enclosed in tubes through a portion only of the cortical sub- 

 stance, the membrane being absent in the deeper layers. 

 The cells are granular, with a distinct nucleus and nucleolus, 

 and a variable number of oil-globules. They measure from 

 TTTO * TTTUTT f an mcn m diameter. Grandry describes 

 three kinds of tubes in what he calls the second layer of the 

 cortical substance ; viz., tubes filled with a strongly-refracting 

 mass of needle-shaped crystals, like crystals of fat ; tubes 

 filled with finely-granular, nucleated cells, containing no fat ; 

 and tubes filled with nucleated cells containing numerous 

 fatty granulations. 8 Between the tubes of the cortical sub- 

 stance are bands of fibrous tissue, connected with the cover- 

 ing of the capsule. 



Medullary Substance. The medullary substance is much 

 paler and more transparent than the cortex. In its centre 

 are numerous openings, marking the passage of its venous 

 sinuses. It is penetrated in every direction by excessively 

 delicate bands of fibrous tissue, which enclose blood-vessels, 

 nerves, and numerous elongated closed vesicles, containing 

 cells, nuclei, and granular matter. These vesicles, -fa of an 

 inch long and about ^-J-^ of an inch broad, have been demon- 

 strated by Grandry in the ox and in the human subject. 

 The cells in the human subject are from 17 1 00 to I2 1 0o of an 

 inch in diameter. They are isolated with difficulty, and are 

 very irregular in their form. The nuclei measure about 

 g-gVff- of an inch. 3 The medullary substance is peculiarly 

 rich in vessels and nerves. 



1 GRANDRY, op. tit., p. 392. M. Grandry makes three layers in the cortical 

 substance ; but these he found more distinct in the inferior animals than in 

 man. The external layer is composed of one, two, or three rows of rounded or 

 ovoid closed vesicles ; the second layer is formed of tubes ; and the third layer 

 is composed of elements like those contained in the tubes, but not enclosed 

 either in tubes or vesicles. This division into three zones had previously been 

 made by Arnold (Journal of Anatomy and Physiology, London and Cambridge, 

 1867, vol. i., p. 147; from YIRCHOW'S Archiv, January, 1866). 



2 Loc. cit. 3 Op. cit., pp. 232, 398. 



