SUPRARENAL BODIES. 549 



ganglia ; while Kolliker also states that the posterior part of the organ is 

 unpaired in the embryo rabbit of 16 or 17 days. 



The structure and development of what I have called the interrenal 

 body in Elasmobranchii so closely correspond with that of the mesoblastic 

 part of the suprarenal bodies of the Reptilia, that I have very 

 little hesitation in regarding them as homologous'; while the paired 

 bodies in Elasmobranchii, derived from the sympathetic ganglia, clearly 

 cori-espond with the part of the suprarenals of Reptilia having a similar 

 origin ; although the anterior parts of the paired suprarenal bodies 

 of Fishes have clearly become aborted in the higher types. 



In Elasmobranch Fishes we thus have (1) a series of paired 

 bodies, derived from the sympathetic ganglia, and (2) an un- 

 paired body of mesoblastic origin. In the Amniota these bodies 

 unite to form the compound suprarenal bodies, the two consti- 

 tuents of w^hich remain, however, distinct in their develop- 

 ment. The mesoblastic constituent appears to form the cortical 

 part of the adult suprarenal body, and the nervous constituent 

 the medullary part. 



Bibliography of the Suprarenal bodies. 



(503) M, Braun. " Bau u. Entwick. d» Nebennieren bei Reptilien." Arbeit, a. 

 d. zool.-zoot. Institut Wiirzburg, Vol. v. 1879. 



(504) A. V. Brunn. "Ein Beitriig z. Kermtniss d. feinern Baues u. d. Entwick. 

 d. Nebennieren." Archiv f. inikr. Anat., Vol. viii. 1872, 



(505) Fr. Leydig. Untenuch. ilb. Pisclie u. Reptilien. Berlin, 1853. 



(506) Fr. Leydig, Roc hen u. Hate. Leipzig, 1852. 



Vide also F. M. Balfour (No. 292), Kolliker (No. 298), Remak (No. 302), etc. 



1 The fact of the organ being unpaired in Elasmobranchii and paired in the 

 Amniota is of no importance, as is shewn by the fact that part of the organ is unpaired 

 in the Rabbit. 



