72 ALBERT KUNTZ 



as having a homogeneous origin; i.e., both the cortical and the 

 chromaffin substance arising from the same source, and by others 

 as having a heterogeneous origin; i.e., the cortical and the chro- 

 maffin substance arising from separate sources. The advocates 

 of the theory of the homogeneous origin of the adrenals have in 

 turn derived them from the mesenchyme, the peritoneal epithe- 

 lium, the germinal epithelium, the epithelium of the pronephros, 

 the epithelium of the mesonephros and from the peripheral part of 

 the sympathetic nervous system. The advocates of the theory of 

 the heterogeneous origin of the adrenals have in turn derived the 

 cortical substance from the mesenchyme, the peritoneal epithe- 

 lium, the epithelium of the pronephros and the epithelium of the 

 mesonephros, while they have in turn derived the chromaffin sub- 

 stance from the mesenchyme and from the sympathetic nervous 

 system. 



A comprehensive review of the literature bearing on the devel- 

 opment of the adrenals would be foreign to the purpose of this 

 paper. An attempt will be made only to indicate the trend of the 

 progress of our knowledge in this field by brief reference to some 

 of the more important papers. For a more comprehensive review 

 of the literature and for a complete bibliography, the reader is 

 referred to the work of Poll 2 ('06). 



The most important investigations on the adrenal system be- 

 fore the classical work of Balfour are those of Leydig ('53). This 

 investigator described both the interrenals and the suprarenals 

 in the fishes and concluded that the latter are derived from the 

 sympathetic nervous system. Indeed, he says, "As the pituitary 

 body is an integral part of the brain, so are the suprarenal bodies 

 part of the sympathetic system." 



The work of Balfour (78) shows conclusively that in the elas- 

 mobranch fishes the interrenals are of mesodermal origin, while 

 the suprarenals are derived from the sympathetic ganglia located 

 along the abdominal aorta. The findings of Balfour were cor- 

 roborated by the work of some of his pupils, notably that of 

 Mitsukuri ('82). 



2 Hertwig's Handbuch, 1906, vol. 3, part 1, chap. 2, pp. 443-616. 



