ON THE LIFE CONDITIONS OF THE OYSTER. 



665 



are carefully -washed before drying, -which -was always done : the result per 

 pair of gills (or oyster) is most in accord with this, and has the advantage 

 of being an easy and in many respects useful basis. 



The relative quantities of iron present in the gills as compared with 

 the rest of the body were next determined in French, Dutch, and American 

 oysters. Six oysters, or the gills of six oysters, were analysed in each 



case with the following results 



From these figures it is evident that the gills of the green French oysters 

 do not contain an excessive quantity of iron such as might account for their 

 colour. Calculated per oyster the gills contain less iron than the rest of 

 the body, except in the American oyster ; calculated as a percentage on 

 the ash the reverse is the case. The proportionate quantity of iron in the 

 gUls as compared with the rest of the body is somewhat greater 

 in the French oysters than in the Dutch, but much less than in the 

 American. 



Clearly, therefore, there is no connection between the green colour 

 and the quantity of iron present. This result is quite in accord with 

 Ray Lankester's observation that his ' marennin ' is free from iron as well 

 as from copper. 



Both the gills and bodies of oysters contain a small quantity of iron, 

 ■which is evidently normally present, the gills containing a somewhat 

 larger amount in proportion to the total quantity of mineral matter 

 present. 



