200 
Proceeclinfis of Royal Society of Edinhurgh. [sess. 
On the Renal Organs of the Asteridea. By Dr A. B. 
Griffiths, F.R.S. (Edin.), E.C.S., &c. 
(Read May 2, 1892.) 
I have already shown * that the secretion of the hve large cardiac 
sacs of the stomach of Urastei' ruhem contains uric acid; and 
consequently these sacs are considered to be the necessary apparatus 
for eliminating the nitrogenous products of the waste of the tissues, 
&c., from the blood or hydrolymph. It may be stated that Mr 
H. E. Durham f has raised the question that there is a possible 
source of error in concluding that these sacs have a renal function. 
He says that “it is possible that the uric acid arrived into the 
starfish’s stomach in the interior of small mussels, &c., whose 
excretory organs contain that body, and of which as food the starfish 
appears to be very fond : anyhow, such a source of the uric acid 
must be eliminated before Griffiths’ conclusion can be accepted ; 
for obviously, if the presence of urates were demonstrated in the 
gastric contents of an individual who had recently supped off 
oysters, it would by no means follow that the stomach was the 
organ whereby the individual excreted his urates.” Certainly not ; 
but Mr Durham has overlooked the fact that if the uric acid had 
been introduced along with the food, I should also have found urea 
in the contents of the starfish’s stomach ; but I conclusively proved 
that urea was absent. 
Now, as a matter of fact, Mr Follows and myself J have shown 
that urea (as well as uric acid) is present in the secretion of the 
organs of Bojanus in the LamelUhrancliiata ; and, therefore, if the 
starfishes had supped off oysters or mussels, I should have found 
urea, in addition to uric acid, in the contents of the stomach. But 
* Proceedings of P^oyal Society of London^ vol. 44 (1888), p. 325. 
t Quarterly Journal of Microscojyical Science, vol. 33 (1891). 
X See the Chemical News, vol. 51, p. 241 ; Proceedings of Royal Society of 
Edinhurgh, vol. 14, p. 230 ; and the author’s book. The Physiology of the 
Invertehrata (Reeve & Co., London). 
