64 



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. 



" 7. 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 pro- 

 portionately 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 those green American Oysters than in the colourless ; 

 but this excess is, proportionately, considerably less than 

 that of the copper. 



"8. 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 Oyster. 



" 9. By treating sections of diseased American Oysters 

 under the microscope with potassium ferrocyanide and 

 various other reagents, we find that the copper reactions 

 correspond in distribution with the green coloration ; and 

 we find, moreover, from these micro-chemical observations 

 that the copper is situated in the blood-cells or leucocytes, 

 which are greatly increased in number. This condition 

 may be described as a green leucocytosis, in which copper 

 in notable amount is stored up in the leucocytes. 



"10. We find that an aqueous solution oi pure hsema- 

 toxylin is an extremely delicate test for copper, just as 

 Macallum found it to be for iron. 



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