350 SECRETION. 



of their function in the adult, have assumed that their office 

 is chiefly important in intra-uterine life. Meckel states that 

 they are easily distinguished in the foetus of two months ; at 

 the end of the third month, they are a little larger and heavier 

 than the kidneys ; they are equal in size to the kidneys (though 

 a little lighter) at four months ; and, at the beginning of the 

 sixth month, are to the kidneys as two to five. In the foetus 

 at term, the proportion is as one to three, and in the adult 

 as one to twenty-three. 1 It was asserted by some of the 

 older writers, that the capsules are larger in the negro than 

 in the white races, but Meckel states that although he had 

 observed this in a negress, he saw nothing of it in dissecting 

 a negro. 2 This observation did not have much significance 

 at that time ; but since it has been supposed that the supra- 

 renal capsules have some function in connection with the for- 

 mation of pigment, authors have quoted it as important. 



The color of the capsules is whitish yellow. They are 

 completely covered by a thin fibrous coat, which penetrates 

 their interior, in the form of trabeculse. Upon section, they 

 present a distinct cortical and medullary substance. The 

 cortex is yellowish, from - T to -fa of an inch in thickness, 

 surrounding the capsule entirely, and constituting about 

 two-thirds of its substance. The medullary substance is 

 whitish, very vascular, and is remarkably prone to decompo- 

 sition, so that it is desirable to study the anatomy of these 

 bodies in specimens that are perfectly fresh. 



/Structure of the Suprarenal Capsules. These bodies 

 have been closely studied by Frey, 3 Ecker, 4 Kolliker, 5 Har- 



1 MECKEL, Manual of General, Descriptive, and Pathological Anatomy, Phila- 

 delphia, 1832, vol. iii., p. 394. 



2 Loc. cit. 



3 FREY, Cyclopaedia of Anatomy and Physiology, London, 1849-1852, vol. iv., 

 part ii., p. 827, Article, Supra-Renal Capsules. 



4 ECKER, Nebennieren, in WAGNER'S Handwdrterbuch der Physiologic, Braun- 

 schweig, 1853, Bd. iv., S. 128, et seq. 



5 KOLLIKER, Manual of Human Microscopic Anatomy, London, 1860, p. 421, 

 et seq., and Handbuch der Gewebelehre des Menschen, Leipzig, 1867, S. 514, et seq. 



