SEA-FISHERIES LABORATORY. 131 



to be the modified representative of the protractor pedis 

 muscle of some other molluscs. 



" 3. A diseased condition we found in certain American 

 Oysters very soon brought us into contact with the vexed 

 question of the ' greening ' of Oysters, and one of the first 

 results we arrived at was that there are several distinct 

 kinds of greenness in Oysters. Some of them, 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 ' described in our former paper to the 

 Royal Society, are not in a healthy state. 



"4. 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., that of the Marennes Oysters) 

 have no connection with copper, but depend upon the 

 presence of a special pigment, ' marennin.' 



" We are able, in the main, to support Prof. Lankester 

 in his observations on Marennes Oysters ; but we regard 

 the wandering amoeboid granular cells on the surface of 

 ihe gills as leucocytes which have escaped from the blood 

 spaces, and have probably assumed a phagocytic function. 



" 5. We see no reason to think that any iron which 

 may be associated with the marennin in the gills, &c, is 

 taken in through the surface epithelium of the gill 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. 



" 6. 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, palp, &c.) 

 of the Marennes Oyster contain either absolutely or 



