ON THE LIFE CONDITIONS OF THE OYSTER. 561 



various parts of the British, French, Dutch, and Italian coasts, we havo 

 arrived at the definite conchisions as to their natural history, chemistry, 

 and bacteriology, which are detailed below ; and to which we have 

 ventured to add some recommendations as to administrative and public 

 health questions. We are convinced that all that is necessary in order 

 that the oyster may be restored to its proper position in public estimation 

 as a most useful, delicate, and nuti'itious food-matter is that shellfish 

 importing, growing, and laying shall be conducted under proper super- 

 vision, and that the grounds and waters chosen for the purpose should be 

 inspected and licensed by duly qualified scientific authorities 



Co7iclusions. 



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.y., the leucocytosis) are certainly asso- 

 ciated 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 

 absorption in the alimentary canal and liver. 



4. We do not find that there is any excessive amount of iron in the 

 green Llarennes oyster compared with the colourless oyster, nor do the 

 green parts (gills, palps, &c.) of the Marennes oyster contain either abso- 

 lutely 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 con- 

 tain 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. 



7. The Colon group of bacilli is frequently found in shellfish, as sold 

 in towns, and especially in the oyster ; but we have no evidence that it 



' Mr. G. C. Bourne informs us that in 1890 he examined some green oysters from 

 Falmouth which showed this leucocytosis. (See Note by Mr. Bourne at conclusion 

 of this report, p. 569.) 



1898. 



