296. Royal Society :— 
of instances, by an excess of food being taken over and above 
the requirements of the system. As regards the constitution of 
this body, I think there can be no doubt that it contains the 
elements of indigo-blue and sugar, and that by oxidation within 
the system it is converted into the ordinary extractive matter of 
urine, which contains, as I have ascertained, the elements of 
sugar and of the black substance which is formed by the action. 
of strong acids on urine, and which may be considered as a pro- 
duct of the oxidation of indigo-blue. Having prepared the ex- 
tractive matter of urme in a state of purity, ascertained its 
composition, aud examined its products of decomposition, I think 
it is probable that the indigo-producing body will be found, as 
regards its formation and composition, to occupy a place between 
the substance of the tissues and the ordinary extractive matter 
iof urine. The very minute quantities of it ordinarily occurring 
n urine, and the difficulty of separating it from the extractive 
matter, make it, however, impossible to ascertain whether this is 
the case or not. My object in making known this portion of 
the iavestigation in its present fragmentary state, is to induce 
medical men, who have an opportunity of examining many 
varieties of urme, to endeavour to discover among these varieties 
some containing a sufliciently large quantity of this body to 
enable the chemist to ascertain its properties and composition. 
The formation of a substance containing the elements of 
indigo-blue in the animal system, is a fact which may lead to 
important conclusions regarding the chemical composition of the 
complex bodies of which the blood and tissues consist. 
XXXV. Proceedings of Learned Societies. 
ROYAL SOCIETY. 
[Continued from p. 234. ] 
February 19, 1857.— Dr. W. A. Miller, V.P., in the Chair. 
NHE following communications were read :— 
«Further Observations on the Anatomy and Physiology of 
Nautilus.’ By John D. Macdonald, Esq., Assistant Surgeon R.N. 
“Brief Deseription of a Ctenostomatous Polyzoon, allied to Vesi- 
cularia, occurring on the Australian Coast.” By John Denis Mac- 
donaid, Esq., Assistant Surgeon R.N. 
«Observations on the Natural Affinities and Classification of Gas- 
teropoda.”’ By John Denis Macdonald, Assistant Surgeon R.N. 
“On the Sea Saw-dust of the Pacific.” By John Denis Mac- 
donald, Esq., Assistant Surgeon R.N. 
ie 
