136 AMERICAN JOURNAL 



ticular places near Iiigh-water mark, and into which the sea can 

 be admitted at pleasure by means of sluices ; the water being 

 kept shallow, and left at rest, is favorable to the growth of the 

 green Confervse and Ulvse ; and with these there are generated 

 at the same time innumerable minute crustaceous animalcules 

 which serve the oysters for food, and tincture their flesh with the 

 desirable hue. 



In 1820, M. Benjamin Gaillon made a series of observations 

 upon this subject, Avhich he communicated to the Academie des 

 Sciences de Rouen, and which led him to the conclusion that the 

 green color of oysters is due to the absorption of microscopic 

 animalcules allied to the Vibrio tripunctatus of Mliller, for 

 which he proposed the np,me of Vibrio osti'earius. These crea- 

 tures he described as gelatinous, linear in shape, pointed at the 

 extremities, rounded in the middle, being also contractile in that 

 part, and charged with a quantity of green fluid. He says that 

 they inhabit the water of the tanks or "parks," in which the 

 oysters are preserved, in such immense abundance at certain 

 seasons of the year, that they can only be compared to the 

 grains of dust which rise in clouds, and obscure the air in dusty 

 weather. 



In a resume of his observations on this subject, which he con- 

 tributed to the "Journal de Physique," Tome XCI., (1820,) p. 

 222, he observes that the change of color takes place only in 

 the "parks " or reservoirs of salt Avater, where the oysters are 

 kept on being brought from the sea. These "parks," which are 

 about 4 feet in depth, 200 to 250 feet in length, by about 50 

 feet in breadth, are capable of containing from 500,000 to 

 600,000 oysters : such are those of Marennes, Oleron, Cour- 

 seuUes, Caen, Havre, Dieppe, Treport, &c. At certain sea.sons 

 of the year, particularly from April to June, and again in Sep- 

 tember, the water becomes, in some of these reservoirs, of a 

 dark green tint; even the small, stones at the bottom of the 

 tanks are covered with small green points or excrescences. 

 Then, says M. Gaillon, the oysters which are destined to assume 

 the same color are placed, with great care, one by one and side 

 by side, in order that none may rest upon any of the others, 

 and the supply of fresh currents of water is suspended for a 

 longer or shorter period, according to the required intensity of 

 the green. 



M. Gaillon rejects the supposition that the change of color is 

 the result of disease, on the ground that, having compared the 

 green oysters with those of the normal tint, he found all the 

 organs quite as healthy in the former as in the latter. 



To the opinion which has often been entertained, that the 



