130 INTERNAL SECRETION 



Nebennieren being called in English " suprarenal bodies "), it is 

 expedient to call them, from their histological characteristics, 

 chromaffine or phasochrome bodies; or, from the nature of their 

 function, they may be termed adrenal organs.* In the Teleostei 

 and Ganoidei, these adrenal bodies are situated in the walls of the 

 cardinal veins. In the Cyclostomata, the adrenal system extends 

 from the neighbourhood of the second pair of gills to the tail ; 

 it takes the form of bands, which are situated between the aorta 

 and the cardinal veins, and are intimately associated with the 

 blood-vessels. 



Comparative anatomy shows that the two fundamental tissues, 

 which in mammals are distinguished as cortex and medulla, are 

 present in all vertebrates, and are therefore to be regarded as 

 structures which are component parts of the vertebrate body. In 

 fish, the two kinds of tissue appear as two different organic 

 systems, anatomically separate from one another, and known as 

 the interrenal and adrenal systems. The interrenal system includes 

 all the structures which, like the suprarenal cortex, are composed 

 of cells with lipoid contents; the adrenal system comprises all 

 tissues the cells of which, like those of the medullary portion of 

 the suprarenal, are characterized by their chromaffinity. 



In the higher vertebrates, however, these systems have, to a 

 differing extent, lost their independence, and have also become 

 very much reduced in size. A partial amalgamation of both 

 systems is seen in the amphibia, the independent portion of the 

 adrenal system here forming isolated cell-agglomerations, which 

 are intimately connected with the sympathetic system. In reptiles 

 and birds, the association between the two systems is more 

 intimate ; though independent portions of the adrenal system are 

 found, in the form of chromaffine bodies, throughout the sympa- 

 thetic system in birds, while in reptiles they lie along the great 

 abdominal vessels. In mammals, the amalgamation of the two 

 systems is complete. This is the result of the topographical 

 arrangement by which the adrenal system becomes the medullary 

 portion, while the interrenal system becomes the cortical portion, 

 of the suprarenal capsules. But even here, a considerable pro- 

 portion of the adrenal system remains independent. It is 

 distributed along the sympathetic system, partly in the form of 

 isolated pha?ochrome cells and larger or smaller chromaffine 

 bodies, and partly in the form of larger structures, invariably 

 found at the bifurcation of the carotid artery and at the abdominal 



* The terms " chromophile " (Stilling), "chromaffine" (Kohn), " phzeo- 

 chrome " or " chrome-brown " (Poll) tissue, indicate a special histological 

 characteristic; the term " paraganglia," suggested by Kohn, has an etiological 

 significance; while the term "adrenal system," in so far as it is not a 

 topographical description but is used as a synonym for " adrenalin- 

 producing organs," expresses the functional significance of these glands. 

 The chrome-brown cells are very aptly termed " cellules adrenalogenes " by 

 Bonnamour. 



