GROSS ANATOMY 13 



which appear anatomically to be homologues of the interrenal 

 tissue. The chromaphil tissue is represented in the lamprey 

 by a series of thin strips running along the large arteries and 

 their branches and extending from the region of the second gill 

 cleft to the tail. 649 



In the hagfish (Bdellostoma myxinidae) chromaphil cells 

 have been described but no interrenal tissue has been iden- 

 tified. 649 



It is only in the Amniota (mammals, birds, and reptiles) 

 that we find the adrenal as a definite organ composed of dis- 

 tinct parts, the chromaphil and interrenal tissues. In the 

 Anamniota (amphibia, fishes, and cyclostomes) the compact 

 union of chromaphil and interrenal tissues has not occurred and 

 these tissues are represented by a number of separate bodies. 

 The amphibia are intermediate between the mammals and the 

 lower Anamniota for in them we find the union of interrenal 

 and chromaphil tissue into a single organ, but without the 

 penetration of the latter tissue to assume a true medullary 

 position. In the fishes and cyclostomes the homologous tissues 

 of the cortex and medulla of the mammal are present as distinct 

 and separate bodies. 



The adrenal system of the Elasmobranchs (sharks, dogfish, 

 and rays or skates) was first described in detail by Balfour. 28 

 He assigned the name interrenal to the homologue of the 

 adrenal cortex of mammals and the name "suprarenal bodies" 

 to the homologue of the medulla. The term "suprarenal 

 bodies" is now replaced by the more suitable term "chroma- 

 phil bodies." The interrenal bodies of the elasmobranchs are 

 usually arranged as a pair of ochre yellow, ribbon-shaped 

 structures lying medial to and in the region of the posterior 

 part of the kidneys. They are sometimes contiguous to the 

 midline and fused into a single organ or joined by strands of 

 tissue. The glands are usually paired in the skate 409 and 

 unpaired in the dogfish and shark. Microscopically the cells 



