On the Suprarenal Bodies of Vertebrata. 



By 



IV. F. R. Weldon, B.A., 



Fellow of St. John's College, Cambridge ; Lecturer on Invertebrate 

 Morphology in the University. 



With Plates XVIII and XIX. 



The suprarenal bodies of Vertebrates are^ as is well known, 

 made up of tveo sets of elements, sharply distinguished from 

 one another, both by their adult structure, and by their mode 

 of origin in the embryo. The substance which from its posi- 

 tion in the mammalian suprarenal is known as " medullary ■" is 

 now almost universally admitted to consist of metamorphosed 

 nerve-cells, which arise from one or more of the ganglia of 

 the sympathetic system. As to the origin of the remainder, 

 however, the so-called " cortical " substance, little is certainly 

 known. In Elasmobranchs, Balfour^ describes the homologuei 

 of this substance as " making its appearance ... as a rod-like 

 aggregate of mesoblast cells, rather more closely packed than 

 their neighbours, between the two kidneys near their hinder 

 ends ; " but he leaves it an open question, whether these cells 

 arise from the general indifferent mesoblast surrounding them, 

 or whether they are derived from any of the adjacent organs 

 of the embryo. 



These observations of Balfour were followed, in 1882, by two 



' " Elasmobranch Fishes," p. 246. 



