PHYSIOLOGY OF THE INVERTEBRATA. 283 



Mr. Follows and the author also examined the blood (of 

 Anodontd) contained in the vena cava before it enters the 

 organ of Bojanus, and it was proved that the blood contains 

 uric acid and urea. After leaving the vena cava the blood 

 passes into the organ of Bojanus and thence to the branchiae. 

 The blood in the branchi^ does not contain uric acid or 

 urea. 



The investigation proves — (a) that the organ of Bojanus 

 is physiologically the kidney of the animal, elimiuating the 

 nitrogenous waste matters (in the form of uric acid and 

 urea) contained in the impure blood as it is brought to this 

 organ by the vena cava ; (6) that after the blood has passed 

 through the organ of Bojanus, it is freed from urea and uric 

 acid. 



The secretion of the organ of Bojanus in Mya arenaria 

 (see Pig. 1 8) contains uric acid, urea, and calcium phosphate. 



Drs. Will and Gorup-Besanez* stated that they found 

 guanin in the organ of Bojanus of the fresh-water mussel, 

 but subsequently Voit could not detect the least trace of this 

 base in the organ in question. Mr. Follows and the author 

 entirely agree with the conclusions of Voit, for we also could 

 not detect guanin in the organ of Bojanus in Anodonta 

 cygnea, although it may be remarked that guanin is present 

 in the green glands of Astacus and Homanm.^ 



The organ of Bojanus appears to be well-developed in the 

 majority of the Zamellibranchiata, but in Ostrea and Teredo 

 it seems to be present in only a very rudimentary form.| 



The nephridia of Helix aspersa and Limax flavus contain 

 uric acid, and were proved by MacMunn § to have a renal 

 function. 



* Ann. der Chem. und Fharm., toI. 59, p. 117; and iiwiic/jen Gelehrte 

 Anzeigen, 1848. 



t See Dr. Griffiths' papers in Froc. Eoy. Soc. of London, vol. 38, p. 187 ; 

 and Proc. Boy. Soc. of Edinburgh, vol. 14, p. 233. 



X See the papers of Lacaze-Duthiers in Annalet des Sciences NatwreUen, 

 1854-1861. 



§ Journal of Physiology, vol. 7, p. 128. 



