512 



Prof. S. Vincent, 



[Apr. 6^ 



average size of cells and nuclei is given above in connection with the- 

 bichromate preparations. 



The vacuoles so prominent in bichromate specimens are not to be seen iiit 

 the preparations fixed in corrosive sublimate or Flemming's fluid (cf. fig. 1 

 with fig. 4). 



As already pointed out by Kohn,* the abdominal chromaphil bodies occur- 

 in two principal forms, the globular and the elongated. These last are often, 

 in the form of threads. The first form is typically found in the human- 

 subject ; the last in other mammals, such as cats and rabbits. In these- 

 animals the threads or columns run separately for the most part, while, as we- 

 have seen, in the dog they are united into a compact ribbon-like organ. 



In the foetal kitten, the chromaphil body is short, almost oval in shape,., 

 and the columns of chromaphil cells form an irregular network. Kohn gives- 

 an excellent drawing of the microscopical structure of this body, so that a. 

 description in this place is unnecessary. 



V. The Adrenal Medulla. 



There is no need to give a description of the general structure of the* 

 medulla of the adrenal. The structure has been described by numerous- 

 observers, and is generally known. It is, however, desirable to institute 

 some comparisons between the histological appearances of the adrenal, 

 chromaphil tissue and this substance as it occurs in other places, as, for 

 example, in the sympathetic ganglia and in the abdominal chromaphil bodies » 



The present observations are confined to the adrenal of the dog, just as the 

 descriptions of the abdominal chromaphil body are limited to this animal. 



A comparison of Plate 13, fig. 1, with fig. 2 or of figs. 3 and 4 with fig. 5,. 

 will show that the general resemblance between extra-adrenal chromaphil 

 tissue and adrenal medulla is very great. Both consist of columns of cells 

 staining yellow or brown with bichromate of potash. The cell-columns are,, 

 however, for the most part much thicker in the adrenal than in the abdominal 

 chromaphil bodies. The blood-spaces are wider, and the wliole aspect gives 

 the impression that the adrenal medulla is more highly organised (see Plato 13,. 

 fig. 2, hid. V, col. c). 



Many of the cells of the adrenal medulla are spherical, as in the abdominal 

 chromaphil body, and their dimensions are the same, viz., about 12 fi in 

 diameter. The nuclei, also, are of the same order of magnitude in both 

 structures, viz., 5 or 6 yit. But in many regions, especially wliero the cell- 

 columns are separated by large venous sinuses, the cells are arranged in a 

 definitely epithelial fashion round tlie blood-vessels (Plate 13, fig. 2, and. 

 * ' Arch. f. inikr. Anat.,' 190.3, m. f.2, 8. 327. 



