The Comparative Histology of the Suprarenal Capsules. 313 



have [1] a series of paired bodies, derived from the sympathetic 

 ganglia, and [2] an unpaired body of mesoblastic origin. In the 

 Amniota these bodies unite to form the compound spurarenal bodies, 

 the two constituents of which remain however distinct in their deve- 

 lopment. The mesoblastic constituent appeai-s to form the cortical 

 part of the adult suprarenal body and the nervous constituent of the 

 medullary part". 



This brilliant hypothesis has been fully confirmed by the in- 

 vestigations of most subsequent embryologists who have worked at 

 different classes of animals, as well as by my own observations upon 

 the comparative physiology and chemistry of the suprarenal capsules 

 [118—122, and 81, 82]. 



In Eeptilia, Braun [11] has fully established the development of 

 the medullary cells from the nerve-cells of the sympathetic ganglia. 



In Birds, Eabl [91] states: "Es bleibt also nichts übrig, als die 

 Markzellen für abgetrennte Ganglienzellen zu nehmen, welche insofern 

 einen, dem embryonalen nahestehenden Zustand zeigen, als ihr Kern 

 nicht den Charakter des Zellkernes einer ausgebildeten Ganglienzelle 

 besitzt und das Protoplasma keine Nervenfortsätze entwickelt hat" 

 and he gives abundant evidence of this view. The cortical substance 

 is derived, according to this author, from the distal end of the pro- 

 nephros. Fusari [39, 40] also supports the view that the medullary 

 part of the suprarenal gland in Birds is derived from the nervous 

 system, and points out in these animals that the groups of "nervous 

 cells" remain distributed between the "epithelial lobules" while in the 

 mammal, the nervous portion assumes a central position. Fusari, 

 however, maintains that the interrenal body of Elasmobranch Fishes 

 is not homologous with any part of the suprarenal capsule, but with a 

 certain adipose tissue found round the suprarenals in some mammals. 

 Von Brunn [12] has also supported the nervous origin of the medulla 

 in Birds. 



In the Mammalia there have been numerous observations, all of 

 them clearly pointing out the totally distinct origin and nature of the 

 cortex and medulla. Thus Mitsukuri [79] worked out the development 

 in the rabbit and the rat. He concludes that the cortical substance 



