294 NATURAL SCIENCE [November 
oyster under normal and abnormal environment, including the effect 
of sewage matters and pathogenic organisms, drawn up by Professor 
Herdman, Professor Boyce, and Dr Kohn, are, we think, of sufficient 
interest to the public to repeat here in full. 
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 (eg., the leucocytosis) are certainly 
associated with the presence of a greatly-increased amount of copper 
in the oyster, while other forms of greenness (¢g., the Marennes) 
have no connection with copper, but depend upon the presence of a 
special pigment Marennin, which may contain 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 absorption 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 is, proportionately, considerably less than that .of the 
copper. 
6. In the Falmouth oysters containing an excessive amount of 
copper, we find that much of the copper is certainly mechanically 
attached to the surface of the body, and is in a form insoluble in 
water, probably as a basic carbonate. In addition to this, however, 
the Falmouth oyster may contain a much larger amount of copper 
in its tissues than does the normal colourless oyster. In these 
Falmouth oysters the cause of the green colour may be the same as 
in the green American oysters. 
