70 



Oyster. Berthelot, however, suggested that the green 

 colour was due to iron, and more recently Chatin and 

 Muntzt have extended and corroborated this statement. 



' From their analytical results these observers conclude 

 that both the green and the brown colourations of various 

 types of French Oysters are due to the presence of 

 iron, and that the depth of colour bears a close pro- 

 portion to the quantity of iron contained. The coloura- 

 tions are chiefly apparent in the gills, but extend also to 

 the labial palps and parts of the alimentary canal. Chatin 

 and Muntz base their conclusions in the first place upon 

 the fact that they find considerably more iron in the gills 

 than the rest of the body of green Oysters ; and secondly, 

 upon the occurrence of a larger quantity of iron in the 

 gills of green than of white Oysters. 



' Appended are some of their results, to which I have 

 added a column, showing the ratio of the iron in the body, 

 minus gills, to that contained in the gills. 



' The relative proportion of iron in the gills hardly bears | 

 out the conclusions arrived at ; it is the same in pale- \ 

 green and brown-green Oysters, and in both, but little j 

 greater than in the white. On the other hand, the total I 



t Compt. Rend., 1892, 118, 17 and 56. 



