THE SUPRARENAL SYSTEM 127 



aroused, and the suprarenals have since formed a constant subject 

 of investigation. A strong impetus was furnished by the new 

 doctrine of the internal secretions and, more particularly, by the 

 discovery of the remarkable physiological activity of the watery 

 extract of suprarenal. 



Since 1896 a large number of publications have appeared 

 (Brauer, Diamare, Fusari, Giacomini, Grynfellt, Kohn, Kose, 

 Pettit, Poll, Soulie, Srdinko, Vincent, Wiesel) in which the 

 suprarenal question is treated from the genetical and from the 

 comparative morphological points of view. 



COMPARATIVE MORPHOLOGY AND EMBRYOLOGY. 



The study of the comparative morphology and of the embry- 

 ology of the suprarenals led to a complete revision of the older 

 theories, and created a new physiological foundation. The results 

 of these investigations are, briefly, as follows : 



Neither morphologically and genetically, nor physiologically 

 and pathologically, are the suprarenals homogeneous organs, but 

 they are the result of the combination of two different and inde- 

 pendent organic systems. The suprarenal complex is derived, 

 not from the whole of these systems, but from different larger 

 portions of them. 



The earlier view, which regarded the suprarenals as inde- 

 pendent homogeneous organs, having a topographical relationship 

 to the kidneys, was a perfectly justifiable one, for it was based 

 upon purely anatomical data obtained from man and the higher 

 mammals. That the physiology and pathology of the suprarenals 

 are largely derived from this anatomical standpoint and continue 

 to be affected by it, is readily comprehensible ; but that this is a 

 cause of much of the haziness by which the subject is surrounded 

 cannot for a moment be doubted. 



The conception of the suprarenals as homogeneous organs, 

 early underwent a certain amount of modification ; for in addition 

 to the principal organs, other structures were frequently observed 

 to be present, sometimes associated with the principal organs and 

 sometimes isolated from them, which could only be regarded as 

 accessory suprarenals. Although the presence, position and 

 structure of these bodies is subject to considerable variation, yet 

 they occur so frequently that they must be regarded as normal 

 structures. The fact that their existence has so often been ignored 

 and their physiological significance insufficiently understood, has 

 been a very fruitful source of error. 



If the conception of the suprarenals as homogeneous organs 

 was shaken by the discovery of these accessory bodies, a con- 

 sideration of their structure served to shatter the theory entirely. 

 Section of the suprarenals shows, even to the naked eye, that they 

 are composed of two sharply defined portions, differing from one 



