73 



medulla especially becoming more and more glandular 

 in structure as we reach the Mammalia. 



3) The sympathetic origin of the medulla is revealed 

 (apart from developmental researches) by the histo- 

 logical structure in the adult in Elasmobranchs, Am- 

 phibians, Reptiles, and Birds, where transition forms 

 are found between nerve-ganglion cells and the proper 

 cells of the medullary substance. 



4) Although the medullary gland is nervous in 

 origin, in the adult it seems to be no longer nervous 

 but glandular, having a characteristic internal secretion. 



5) The medulla of the suprarenal capsule in the 

 higher Vertebrates corresponds to the paired supra- 

 renal bodies along the sympathetic in Elasmobranch 

 fishes. 



6) The cortex in the higher orders corresponds to 

 the interrenal body in Elasmobranch fishes. 



Since writing the above I have become acquainted with the papers 

 of Dr. AiCHEL (1, 2, 3) who has expressed views which are strikingly 

 at variance with those above stated. He derives both parts of the 

 mammalian suprarenal from the nephrostomes of the mesonephros 

 and considers that the medullary substance is not a separately derived 

 tissue but part and parcel of the same "Anlage" which has become 

 secondarily differentiated from it, and has nothing to do with the 

 sympathetic. 



He disputes in toto the homologies I have urged so often and 

 from so many different standpoints and goes so far as to state that 

 even the paired suprarenals of Selachians are not derived from the 

 sympathetic, while the interrenal body of this group is the homologue 

 of the suprarenal body of the higher Vertebrates. He homologises 

 the paired suprarenals of the Elasmobranchs with certain bodies he 

 describes in connection with the reproductive organs in Mammalia^). 



I gather from a perusal of Dr. Aichel's papers that his sole 

 evidence for this way of looking at the question is derived from 

 embryological research, and I would point out in the most emphatic 

 manner the danger of exclusively employing one method of study in 



1) I cannot find, however, in his paper any reference to the 

 occurrence of chromogenic cells in these bodies, nor any characteristic 

 physiological substance, both of which are so strikingly present in the 

 paired bodies of Elasmobranchs. 



