86 Our Food Mollusks 



Green oysters appear in certain basins along the Eu- 

 ropean coast, and the color has happened to strike the 

 popular fancy. Such oysters are practically unmarket- 

 able in America, where they also appear, though they 

 are as wholesome as any others; but in Europe, and in 

 France in particular, they are very highly prized by 

 connoisseurs on account of their " peculiarly delicate 

 and delicious flavor" — which, if it exists at all, does 

 not arise from the green coloring matter. 



Most of the green oysters found in the European 

 markets come from Marennes in France. Here in the 

 tide basins are great numbers of green diatoms, organ- 

 isms used by oysters for food, that collect in such num- 

 bers that they form what is termed a " moss." To this 

 is ascribed the green color assumed by oysters growing 

 near it. Here it was discovered by the culturists that 

 the " moss " developed most rapidly in very muddy in- 

 closures in which water was seldom changed. These 

 basins, or claires, are usually situated so high as to be 

 filled only once or twice during the month. The tem- 

 perature of water held in such a manner rises several 

 degrees, and this condition is found to be very favorable 

 to the multiplication of diatoms. But while it produces 

 oyster food in great abundance, the water loses so much 

 of its oxygen during its stagnation, that it affects oysters 

 adversely. Those individuals that are able to endure 

 the conditions, are said to fatten rapidly, but the mor- 

 tality is usually great, being in most cases at least 

 fifty in a hundred. There is an extreme variation in 

 the rate at which the green coloration is acquired 

 by the living oysters, the necessary time in some 

 claires being two or three weeks, in others as many 

 months. 



