SECT. 194.] THE SUPRARENAL CAPSULES. 425 



malia), an extremely rich net-work of dark-bordered, fine tubes 

 enclosed in the trabecular of connective tissue, although their ter- 

 minations are nowhere perceptible. In man, the medulla is so 

 altered, that the nerves can be traced only to their entrance into 

 it, and their further distribution it has not hitherto been possible 

 to ascertain. 



§ 194. Physiological Remarks. — The suprarenal capsules are 

 developed contemporaneously with the kidneys, and independently 

 of them, from a blastema, which arises from the middle germinal 

 lamina (Remak), and about the first appearance and growth of which 

 nothing is known. These organs are, at first, larger than the 

 kidneys j but in the third month, they are equal to the kidneys 

 in size ; in the embryo of six months, the weight of the suprarenal 

 capsules is to the kidneys as 2 to 5 ; in the mature foetus, as 1 to 

 3; in the adult, as 1 to 8 {Meckel). In the lower mammalia, the 

 suprarenal capsules are from the commencement onwards smaller 

 than the kidneys, and grow in the same ratio as the latter. Very 

 little is known concerning the histological development of the 

 organ. I have investigated it hitherto only in an embryo of three 

 months, where, like Ecker, I found the cortex whitish, the medulla 

 reddish-white, and both consisting of cells and fibres. The cells 

 measured 0-012'" to o - 02'" in diameter: they had beautiful, in 

 part colossal, nuclei, with splendid nucleoli, as well as fat mole- 

 cules in the cells of the cortex. I have not yet seen anything of 

 the development of the nerves. Ecker saw nothing of the tubes 

 in a newly-born rabbit, but found them very distinct in a calf 

 embryo, \\ feet in length; but they were small, measuring only 

 005 to o' 1 5 of a millimetre. 



In the absence of all physiological data, and in our ignorance of 

 the exact distribution of the nerves within the organ, any remarks 

 on the functions of the suprarenal capsules must at present be of 

 the most general nature. I will only remark, that I regard the 

 cortical and medullary substances as being physiologically different. 

 The former may, for the present, be classed with the so-called 

 vascular glands, and some relation to secretion may be ascribed to 

 it; whilst the latter, on account of its unusual richness in nerves, 

 must be considered as an apparatus belonging to the nervous 

 v >em, in which the cellular elements and the nervous plexuses 

 either influence each other in a similar manner as in the gray 

 nervous substance, or are related to each other in some other way 



