80 K. MITSUKURI. 



of connective tissue, and stands out distinctly. There is, 

 however, a reaction very characteristic of the medullary cells 

 which is most useful in identifying them. When the supra- 

 renals are hardened in bichromate of potash, the medullary 

 substance is stained brown or yellow, and is sharply marked 

 off from the cortical part. It occupies an area in the centre 

 corresponding roughly to the outline of the section. The 

 boundary between it and the cortical part is, however, most 

 irregular, the latter sometimes going into the midst of the 

 former, which, in its turn, may send long processes out- 

 wards. In the last case we jind almost invariably that the 

 processes become continuous with nerve fibres, which fre- 

 quently traverse the cortical substance from the capsule 

 toward the medulla. 



Different authors have stated that the medullary part of 

 various animals is very rich in ganglion, cells. In the rabbit 

 they are very scarce. Out of the numerous sections I have 

 cut there is only one that shows undoubted nerve cells in 

 the medulla. Large veins are found in this part (see fig. 1), 

 and capillary spaces {d, fig. 2) are visible between cell 

 groups. 



Keference has been made to the posterior end of the 

 suprarenal, where the medullary substance reaches the out- 

 side of the organ. By studying the consecutive sections of 

 this part, we find the medullary cells following the vein to 

 the posterior part, and finally, near the exit of the latter, 

 emerging on the exterior. In the suprarenals of the fully- 

 grown rabbit, the band of cells which follows the vein is 

 rather narrow, while in those of young examples it is as 

 wide as any part of the medullary substance. Fig. 2 is a 

 longitudinal section of the posterior end of the suprarenal of 

 an adult. The upper end of the figure is the posterior 

 extremity of the suprarenal. The areas marked <?, c, c, are 

 occupied by cortical cells. If we follow the medullary sub- 

 stance {in m) a few sections towards the median plane of 

 the suprarenal, we should find the point (x) gradually 

 approaching the middle line of the section, and finally 

 uniting with the main mass of the medullary substance in 

 the centre of the organ. It will be seen in the figure that 

 the medullary substance emerges at two points — on the 

 top, and on the left side — and spreads itself over more or 

 less wide areas on the surface of the suprarenal. At^it 

 becomes continuous with irregular cords (h), made up of 

 cell groups, which are exactly like those of the medulla, 

 and some of which are stained yellow by bichromate of 

 potash. They are, in fact, a part of the medulla. These 



