74 



that ill these parts microscopic tests show the presence of 

 granules of iron. The actual meaning of these results 

 can hardly be recognised without quantitative data. 



' The Presence of Copper in Oysters. — Fredericq has shown 

 that a certain small amount of copper is present normally 

 in the haemocyanin of the blood of crustaceans and 

 molluscs. 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"18 per cent, on the ash. 



' 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 

 probably to this last factor that the popularly recorded 

 differences in taste of the various kinds of oysters is really 

 due. Certainly the minute quantities of copper and iron 

 present cannot account for them. 



' The copper was also determined in the gills and in the 

 bodies minus gills of French, Dutch, and American 

 Oysters, with the following results : — 



