MAEINE BIOLOGICAL STATION AT POET ERIN. 39 



" 1. There are several distinct kinds of greenness in 

 oysters. Some of these, such as the green Marennes 

 oysters and those of some rivers on the Essex coast, are 

 healthy; while others, such as some Falmouth oysters 

 containing copper, and some American oysters re-bedded 

 on our coast, and which have the pale green leucocytosis 

 we described in the last report, are not in a healthy state. 



" 2. Some forms of greenness {e.g., the leucocytosis) are 

 certainly associated with the presence of a greatly-increased 

 amount of copper in the oyster, while other forms of 

 greenness {e.g., the Marennes) have no connection with 

 copper, but depend upon the presence of a special pigment 

 Marennin, which may be associated with a certain amount 

 of iron. 



" 3. We see no reason to think that the iron in the 

 latter case is taken in through the surface epithelium of 

 the gills and palps ; but regard it, like the rest of the iron 

 in the body, as a product of ordinary digestion and absorp- 

 tion in the alimentary canal and liver. 



" 4. We do not find that there is any excessive amount 

 of iron in the green Marennes oyster compared with the 

 colourless oyster; nor do the green parts (gills, palps, 

 &c.) of the Marennes oyster contain either absolutely or 

 relatively to the colourless parts (mantle, &c.) more iron 

 than colourless oysters. We therefore conclude that there 

 is no connection between the green colour of the 'Huitres 

 de Marennes ' and the iron they may contain. 



"5. On the other hand, we do find by quantitative 

 analysis that there is more copper in the green American 

 oyster than in the colourless one; and more proportionately 

 in the greener parts than in those that are less green. We 

 therefore conclude that their green colour is due to copper. 

 We also find a greater quantity of iron in these green 

 American oysters than in the colourless ; but this excess 



