314 S. Vincent, 



arises from the mesoblast, while the medullary substance is derived 

 from the peripheral part of the sympathetic nervous system, and is 

 at first placed outside of the cortical substance, becoming transported 

 into the middle of the suprarenal body in the course of development. 

 Inaba [57] who studied the development in the mouse, found that the 

 cortex develops as a proliferation of the peritoneum at the angle of 

 the mesentery and laterally continuous with the beginning of the 

 generative organ, while the medulla is derived from the sympathetic 

 elements, which enter the organ in the 14*^ day embryo. They 

 increase and form a reticulated mass at the centre, from which the 

 cortical cells are gradually pushed aside. The connection with the 

 sympathetic system is usually cut towards the close of gestation but 

 in some may be retained till after birth. 



Mihâlkovics [77] has traced the cortical blastema from the Ger- 

 minal epithelium of the coelome, and this conception, viz: that the 

 cortex of the suprarenal capsule and the genital glands have the same 

 origin is the one now usually admitted. 



Gottschau [45] and Janosik [58] deny the nervous origin of the 

 medulla and state that this is formed from the cortex. Creighton [22] 

 even goes so far as to say that "the distinction between the cortex 

 and medulla of ordinary anatomy is quite arbitrary, as there is no 

 real difference between their constituent cells. The central part or 

 medulla is only more spongy than the rest". This view, contrary to 

 all sound evidence on the subject and only requiring the most casual 

 observation in order to be refuted, has nevertheless been supported 

 by RoUeston [100] so recently as 1895. 



Valenti [114] thinks the suprarenal is a "rudimentary organ" (!). 



Summing up what is known about the development of the supra- 

 renal capsules, it seems probable that the cortex is derived from the 

 germinal epithelium, while the medulla is derived from the nerve-cells 

 of the sympathetic ganglia^). 



^) If the medulla of the mammalian suprarenal capsule be derived phylo- 

 genetically from the series of paired suprarenal bodies of Elasmobranch fishes, it 

 is probable that only those bodies in the region of the kidneys and reproductive 

 organs have actually entered into the formation of the gland in higher animals. 

 What has become of the rest? Are they unrepresented in Mammalia? It is in- 



