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 Amiwrus catus a position similar 
to that which Hyrtl' 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 macerated in Miiller’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 Stannius that these structures may vary 
greatly in number in individuals of the same species, and arise in an 
1 Das uropoetische System der Knochenfische. Sitz. Wiener Akad. 1851. 
