1910.] The Chromaphil Tissues and the Adrenal Medulla. 511 



from each other by strands of connective tissue with a large amount of 

 elastic tissue and blood-vessels and nerves. In the spaces between the 

 columns is also accumulated a quantity of homogeneously stained material 

 which appears to resemble the colloid of the thyroid. This seems to be in 

 some instances contained in lymph spaces. 



The cells are irregular in shape (Plate 13, fig. 4), but tend, like those of 

 the chromaphil groups in the sympathetic ganglia, to be circular in outline 

 {</. Plate 13, fig. 3 and fig. 4, chrom. c). They have an average diameter 

 of about 12 fi. Thus they are slightly smaller than those in the ganglia. 



The protoplasm is very finely granular or almost homogeneous, and the 

 intensity of the brown coloration varies considerably in different cells 

 (Plate 13, fig. 4), so that their outlines are often indicated by this means. 

 Some cells scarcely show the brown coloration, and the region of the 

 protoplasm is indicated as a light ring round the nucleus. 



A very striking feature of tl)e preparation is the appearance in all parts of 

 the section of a number of clear spaces with very definite outlines 

 (Plate 13, fig. 4, ^•). These appear in many instances to contain a substance 

 resembling the colloid above referred to, and occur both between tlie cells 

 and within their substance. 



The nuclei are 5 or 6 in diameter, and resemble those of the groups of 

 chromaphil cells within the ganglia (Plate 13, figs. 3, n, and 4). In many of 

 my slides a very interesting arrangement is seen. The nuclei of the cells 

 are frequently disposed in a regular row around the circunifeieuce of the cell- 

 columns. 



When the material is fixed in corrosive sublimate and subsequently stained 

 with hiemalum or carmalum many of the features above described are seen 

 with greater distinctness. Thus the cell outlines are more regularly and 

 more distinctly seen, and the shape and relations of the cell-columns are 

 more easily studied. Specimens of the abdominal chromaphil body of the 

 dog have been removed immediately after the death of the animal, and after 

 being pinned out on cork to prevent shrinking or curling have been fixed in 

 acid mercuric chloride solution. Sections have been subsequently cut in 

 three directions, viz., transversely, longitudinally and horizontally, and 

 longitudinally and vertically (Plate 13, fig. 1). 



The organ is surrounded by a connective tissue capsule containing vessels 

 and nerves (fig. 1, c). It is clear that the cell-columns run longitudinally, 

 and are somewhat wider in the horizontal than in the vertical direction. 

 There is considerably more variation in the width of the columns in a 

 horizontal direction than in the vertical. In the former direction the 

 columns have an average width of 52 /x., in the latter about 22 fi. The 



