PERILS OF THE OYSTER. 223 



green tint. Is this why such oyster plantations are termed 

 parks ? 



"At Marennes these reservoirs are called claires. They 

 are inundated fields, which stretch on each side the banks 

 of the Seudre for many miles. The claires of Marennes 

 differ from the oyster parks of other localities in this that 

 while the parks are submerged by the rising waters of every 

 tide, the claires are only covered at spring-tide. 



" An oyster six or eight months old requires two years 

 before it reaches the point of perfection ; but it is very 

 seldom that the oysters eaten in Paris undergo these con- 

 ditions ; generally the adult oyster is placed in the claires, 

 and in a few days it begins to have the characteristic green 

 tint. The green colour is not general, but is particularly 

 shown in the region of the branchiae, upon the labial 

 feelers, and in the intestinal canal. What this colour is 

 has long been a subject of conjecture. It certainly differs 

 from all other colouring matters, and Berthelot has shown, 

 by a chemical analysis, that it has some peculiarities. 

 Some naturalists believe that it is produced by a disease of 

 the liver, caused by the unnatural position of the oyster ; 

 certainly this would give a green hue to the parenchyma. 

 Another opinion is, that the colour is from an accumulation 

 of animalculae, which are lodged in the tinted parts. 

 Priestley suggests that it is the peculiar green colour which 

 is generally produced in water exposed for a long time to 

 the action of light ; but the most probable solution of the 

 difficulty appears to be that it is in some way due to the 

 soil of the claires. The green molecules are arrested by 

 the branchiae, and thus the action of the organ is much 

 impeded. The poor animal, injured in one of its essential 

 parts, seems to dilate and become more tender, and for 



