IRON AND COPPER IN OYSTERS. 



25 



It is evident from the last table that both the gills and the rest of the body of 

 oysters contain normally (as would naturally be expected) a small quantity of iron, 

 the gills having a somewhat larger amount in proportion to the total quantity of mineral 

 matter present, but quite irrespective of the colour of the gills. 



II. — Determination of the Copper. 



Harless and Bibra* first showed that phosphate of copper was present in the 

 blood of Molluscs (Cephalopoda), and Fredericq subsequently extended the observation! 

 and proved that a certain small amount of copper is found normally in the blood of 

 various Shellfish (both Crustaceans and Molluscs). It is apparently in combination with 

 a proteid, to which Fredericq gave the name " hemocyanine." 



The quantity thus present in oysters of different origin is fairly constant, as shown 

 in the following table : it varies from 0.25 to 0.66 mgrme. per oyster, or from 0.30 to 

 1. 1 8 per cent, on the ash: — 



For copper, then, 0.4 mgrme. per oyster may be taken as an average, a quantity 

 slightly greater than the average iron (0.26 mgrme.). The calculated percentages on the ash 

 show greater variations, due to the very considerable differences in the total quantities 

 of mineral salts present ; and it is very possibly to this last factor that the well-known 

 differences in taste of the various kinds of oysters is at any rate in part due. Certainly 

 the minute quantities of copper and iron present cannot account for the flavour, as has 

 been sometimes suggested. 



The copper was also determined in the gills, and in the bodies minus gills, of 

 French, Dutch, and American oysters, with the following results : — 



* Muller's Archiv, 1847. 



t Rech. s. 1. Physiologic du Poulpe, Arch. Zool. Exper., t. VII. (1878). 



c 



