1887.] Nephridia and "Liver" of Patella vulgata. 393 



When these crystals are treated with nitric acid and then gently 

 heated with ammonia, reddish-purple mnrexide [C 8 H 4 (NH 4 )N 5 6 ] is 

 obtained which crystallises in prisms. 



(&.) Another method was used for testing the secretion of the 

 nephridia of Patella. 

 The secretion was boiled in distilled water, and evaporated care- 

 fully to dryness. The residue so obtained was treated with 

 absolute alcohol and filtered. Boiling water was poured upon 

 the residue, and to the aqueous filtrate an excess of pure acetic 

 acid added. After standing about seven hoars, crystals of 

 uric acid (C 5 H 4 N 4 3 ) were deposited, and easily recognised by 

 the chemico-microscopical tests mentioned above. 



The secretions both of the left and right nephridia yield uric acid. 

 It has been suggested by Mr. R. J. Harvey Gibson, M.A., F.R.S.E. 

 (in his masterly memoir on the " Anatomy and Physiology of Patella- 

 vulgata;" ' Edinb., Roy. Soc. Trans.,' vol. 32, pp. 601—638), that the 

 secretions of the two nephridia may be chemically distinct. The 

 author could not extract or detect (after a most searching investiga- 

 tion) the presence of any other ingredient besides uric acid in either 

 secretion. 



Prom this investigation, the isolation of uric acid proves the renal 

 function of the nephridia of Patella vulgata. 



II. The " Liver " of Patella vulgata. 



In a paper on the Cephalopod "liver" ('Edinb., Roy. Soc. Proc., r 

 vol. 13, pp. 120 — 122), the author proved from a chemical and micro- 

 scopical study of its secretion that it possesses the function of a true- 

 pancreas or digestive organ. 



Since the publication of the above paper, the author has investi- 

 gated the nature of the secretions of various doubtful organs of the 

 Invertebrata.* 



The " liver " of Patella is a yellowish saccular gland, and the greater 

 bulk of this organ is encircled by the superficial coil of the intestine. 



(a.) The secretion of the gland acts upon starch-paste, converting- 

 the starch into glucose-sugar, as proved by the use of Fehling's- 

 solution. 



(6.) The secretion produces an emulsion with oils and fats, yielding- 



subsequently fatty acids and glycerol, 

 (c.) When a few drops of the secretion of the gland are examined 



* See Dr. Griffiths' paper, " Researches on the Problematical Organs of the 

 Invertebrata, especially those of the Cephalopoda, Gasteropoda, Lamellibranchiata r 

 Crustacea, Insecta, and Oligochseta." — Eead before the Royal Society of Edin- 

 burgh, May 16, 1887. 



