THE SUPRARENAL SYSTEM 1 29 



This, at least anatomically, isolated suprarenal of the 

 am n iota is absent in the anamniota, where it seems to be replaced 

 by a number of small bodies, partly connected and partly entirely 

 separate. The amphibia represent, to a certain extent, the tran- 

 sition stage between the higher and lower vertebra?. In the anura 

 (frogs, toads), the yellow bodies which represent the suprarenals 

 are united to form a thin plate which is attached ventrally and 

 medially to the kidneys ; in the gymnophiona (blind worms), they 

 are united at least at the head end to form a largish mass, and 

 the cordal part only is broken up into separate portions; in the 

 urodela (salamander, newts), they are divided into numerous small 

 islands, situated close to the kidney and along its entire length. 

 The histological relationship between these organs of the amphibia 

 and the suprarenals of the amniota is shown by the fact that, in 

 addition to the larger portions, composed of rows of cells with 

 lipoid contents, chromaffine tissue is also present in isolated 

 groups of cells and cell-masses which, in the anura, form an inter- 

 communicating network of intermediary columns. 



In all vertebrates lower than the batrachians, the suprarenals 

 are replaced by two topographically separate systems of small 

 bodies.* The only exception is the amphioxus, in which no 

 cell-groups of a structure similar to suprarenal tissue have as 

 yet been found. 



The one system includes the entire body, described in the 

 Selachii under the name of " interrenal body," lying between the 

 caudal end of the kidneys ; in the Teleostii, the so-called 

 ' corpuscle of Stannius " ; and in the Ganoidei, the corpuscles dis- 

 tributed throughout the whole kidney, likewise described by 

 Stannius; as well as the small structures which, in cyclostomata, 

 are attached to the walls of the posterior cardinal veins and 

 extend from the region of the pronephros (head kidney) to the 

 tail. Histologically, all these bodies are exclusively composed 

 of cells arranged in vesicles or tubules. The cells contain lipoid 

 granules and their structure is therefore similar to that of the 

 suprarenal cortex. 



The second system is chromaffine in character and comprises 

 those paired bodies, associated with the sympathetic ganglia and 

 lying dorsally to the kidneys in the caudal rump-part of the body, 

 which, in the Selachii, are called the suprarenal organs. But as 

 this terminology is liable to lead to confusion (the German 



* The question as to whether or not the invertebrates possess organs 

 equivalent to the suprarenals was first propounded by Leydig. He observed 

 peculiar cells with yellow granular contents against the nerve fibres and 

 ganglia of Paludina, Pontobdella and Mermis, and regarded these as the 

 counterparts of the suprarenals. Poll and Sommer found chrome-brown 

 cells in the central nervous system of leeches, and Poll 'found similar cells 

 in the abdominal ganglia of Hirudo, Aulastoma, Placobdella, and Xephelis. 

 I myself found that the extract of the abdominal ganglia of Hirudo 

 mcdicuialis and Lumbricus terrcstris contained adrenalin, and this may be 

 proved by biological methods. 



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