232 Proceedings of Poyal Society of Edinburgh, [may 16 , 
(b) Another method was applied to the clear liquid secreted by 
the nephridia. The liquid was boiled in distilled water, and 
evaporated carefully to dryness. The residue so obtained was 
treated with absolute alcohol, and filtered. Boiling water w r as 
poured upon the residue on the filter paper, and to the aqueous 
filtrate an excess of acetic acid was added. After standing 6 f 
hours, crystals of uric acid were deposited, and recognised by the 
chemico-microscopical tests already mentioned above. Further, it 
was found that there was a small quantity of uric acid in the blood 
of the vena cava, before it entered the nephridia ; but the blood 
after passing into the branchiae contains no uric acid. From these 
reactions, the secretions of the nephridia contain uric acid and 
calcium phosphate, and prove that the nephridia of the Cephalo- 
poda are true renal organs getting rid of the nitrogenous waste 
matters, in the form of uric acid, contained in the pure blood as it 
is brought to these organs (nephridia) by the vena cava. 
(ii.) On the Renal Organs of Astacus fluviatilis, Anodonta cygnea, 
Limax flavus, Helix aspersa, and Periplaneta orientalis. 
It will be remembered that in a paper ( Proc . Roy. Soc., vol. 
xxxviii. Ho. 236, p. 187) before the Boyal Society of London, I 
have shown that the secretions of the so-called “ green glands ” of 
Astacus fluviatiliis (crayfish) can be made to yield uric acid 
(C 5 H 4 H 4 0 3 ) and guanin (C 5 H 5 H 5 0), showing these glands are 
analogous in physiological function to the kidney of the higher 
forms of animal life. 
Mr Harold Follows, F.C.S., and myself (Chemical Pews, vol. li. 
p. 211, and Jour. Cliem. Soc. [Abstracts], 1885, p. 921) have 
established the renal functions of the organs of Bojanus in Ano- 
donta cygnea (fresh-water mussel), by the isolation of uric acid 
and urea from the secretions of those organs. 
The isolation of uric acid crystals from the problematical renal 
organs of the Invertebrata, commenced by myself (in my Boyal 
Society’s paper on the green gland of Astacus) led Dr C. A. 
MacMunn, M.A., F.C.S. (Journal of Physiology , vol. vii. Ho. 2, 
p. 128) to prove the renal function of the Malpighian tubes of 
Periplaneta orientalis , and in the nephridia of Helix aspersa and 
Limax flavus. 
