310 S. Vincent, 



fibres being discoverable. De Mattei [75] also appears to have de- 

 scribed these fibres, but 1 have not been able to obtain access to his 

 paper. In the ox these bundles of muscular fibres are very striking. 

 As far as my own observations extend, they appear to be present 

 only in the larger capsules (i. e. in ox, horse, man &c.). 



The nerve-terminations in the suprarenal capsules have been in- 

 vestigated by Dogiel [27] and Fusari [41, 42]. The nerve-fibres come 

 for the most part from the solar plexus. After a course of variable 

 length in the connective-tissue capsule, they penetrate perpendicularly 

 the cortical substance and bury themselves in the medulla. The nerve- 

 supply to the medulla is much more strongly developed than that to 

 the cortex, and in the former the relations of the nerves to the glan- 

 dular cells are much more intimate. In the medulla of large capsules 

 such as those of the ox, large nerve-fibres cut in various directions, 

 and groups of nerve-cells of differing sizes are frequently to be seen. 

 But nerve-cells are rarely to be found in the substance of the supra- 

 renals of smaller animals. 



Cortex. In many aspects the cortical portion of the suprarenal 

 capsule is to be looked upon as the more important constituent of 

 the organ in the Vertebrata. Thus from Elasmobranchs upwards this 

 part is always present, while in Teleosts (and most probably Ganoids) 

 the medulla is wanting. Then, again, in most animals the cortex is 

 much more adundant than the medulla, and has a very regular glan- 

 dular aspect even in Elasmobranchs. The medullary portion on the 

 other hand appears to undergo a progressive evolution as we ascend 

 the scale of the Vertebrata, and it is not until we reach the Mammalia 

 that it partakes of the nature of a true internal-secreting gland. ^) 



So that we may look upon the cortical gland as the principal or 

 primary constituent of the suprarenal organ, to which certain cells 

 derived from the sympathetic nervous system have become related. 

 As this relation becomes more intimate the medulla gradually becomes 

 included within the substance of the cortex and takes on a distinctly 

 glandular form. 



^) That is, as regards its histological structure. This characteristic secretion 

 is already elaborated even in Elasmobranchs [120, 121]. 



