ANATOMY, EMBKYOLOGY AND HISTOLOGY 67 



anatomically. In selachians the medullary part is represented by small 

 paired masses of chromaphil tissue in close association with the sympa- 

 thetic ganglia (Fig. 5). These have been commonly called "suprarenals," 

 but it seems better to restrict the use of the term "suprarenal" to the two 

 associated systems as they occur in the higher forms. The word "adrenal" 

 has also been applied to them, and Biedl considers this to be not so objec- 

 tionable, since, ignoring the old topographical meaning, it may \>e> taken 

 to signify that on extraction they yield "adrenalin." The cortex, on the 



Chromaphil bodies 

 Sympathetic ganglia 

 Sympathetic nerve 



Accessory cortical 



Inter-renal body. 



Kidney 



B 



, -Carotid body 



- .Superior cervical ganglion 



Inferior cervical ganglion 

 tellate ganglion 



cessory cortical body 

 ^.Suprarenal cortex 

 Suprarenal medulla 

 diromaphil cells 



Kidney 



Abdominal chromaphil body 

 Accessory cortical body 

 near testicle 



Sympathetic ganglia 



Ch roma^i il cells 



Fig. 5. Diagrams of the condition of the suprarenal apparatus in a selachian 

 (A), and in man (B), after Vincent. 



other hand, is represented by a much larger single median structure called 

 an "interrenal body." 



In Amphibia. As we pass upward in the scale, these primitive rela- 

 tions are lost. A transitional condition is met with in amphibians, in 

 which the close association of the adrenal (chromaphil) tissue with the 

 sympathetic ganglia is to some extent lost and a partial connection with 

 the interrenal system is effected. 



In Reptiles and Birds. In reptiles and in birds the association is still 

 closer, but it is only in mammals that the adrenal tissue penetrates into the 

 interrenal and becomes definitely enclosed by it, forming the medulla of 

 the definitive suprarenal gland. 



Even in man, all the adrenal tissue is not disposed of in this way, for 

 some of it retains its independent condition, being distributed in various 

 parts of the body, where it has already been discussed under the heading 

 of chromaphil bodies. The genetic relationship, if any, between this 



