BLOOD-VASCULAR SYSTEM, ETC., OF AMIURUS CATUS. 437 



frequently confounded. The condition of the pseudobranchia and 

 thymus in the adult would suggest the probability that an examina- 

 tion of the embryonic and young stages of those fishes in which 

 they have not been found would show rudiments to be present. 



THE SUPRARENAL BODIES. 



In view of the relationship of these bodies to the sympathetic 

 nervous system as established by the studies of Leydig, Semper and 

 Balfour on their development, an apology is due for placing them in 

 relation to what are considered blood-glands. The sympathetic 

 system, however, has not been examined, nor yet the relation of 

 these bodies to it ; and further, many persons still hold that their 

 function is to effect some change upon the blood. This point will be 

 noticed further on. 



The suprarenal bodies occupy in Amiurus catus a position similar 

 to that which Hyrtl 1 found obtaining in other Siluroids. They are 

 represented by a single pair lying one on each side of the kidney 

 imbedded in its lateral surface, where they are readily distinguisha- 

 ble as small white spots in the dark red gland. Sometimes, how- 

 ever, the kidney substance having pressed in between them and the 

 body-wall they are entirely concealed. No definite position can be 

 assigned to these bodies with reference to the surface of the kidney, 

 but they always lie near a pair of renal arteries which vary their 

 course upon the middle third of the lateral wall. One series of 

 sections showed the suprarenal body lying in a fork of the artery, 

 with its capsule so intimately joined to the wall of the latter that 

 their limits could not be defined. A branch from this artery sup- 

 plies the organ with blood. 



It is not uncommon to find instead of a single body two or even 

 three bodies on one or both sides. I regard these as divisions of the 

 simple one, because they are always smaller and are related to 

 branches of the same artery. Further, when a suprarenal body has 

 been ma.cerated in Midler's fluid it shows a tendency to divide into two 

 or three parts. These division lines were seen in section as processes 

 of connective tissue from the capsule. It would appear, however, 

 from the observations of Starmius that these structures may vary 

 greatly in number in individuals of the same species, and arise in an 



1 Das uropoetische System tier Knochenfische. Sitz. Wiener Akad. 1851. 



