Mr. A. W. E. O’Shaughnessy on Green Oysters. 223 
cases on record in wnich fatal consequences have followed their 
use as an article of food, there is reason to suspect that copper 
has been the chief cause of the evil. 
So far back as the year 1713, mention is made of a certain 
luxurious supper given by an ambassador at the Hague, who, 
in order that no delicacies might be wanting, procured green 
oysters from. England. All who eat of them are said to have 
been immediately seized with severe colics, and to have been 
cured with great difficulty. Lentilius, on whose authority this 
account rests, states that it was afterwards ascertained that the 
merchant, whom he anathematizes with his whole race, had 
palmed upon the ambassador some common oysters tinted with 
copper, for the true greens*. 
Another case is recorded by Dr. Chisholm in the ‘ Edinburgh 
Medical and Surgical Journal,’ vol. iv. p.400. He was informed 
by Mr. William Newton, of St. Croix, that some time after the 
British frigate ‘Santa Monica’ was cast away on the coast of the 
island of St. John (one of the Virgin Islands), oysters grew on 
her bottom, which was coppered. Many people ate of these 
oysters; and although the consequence was in no case fatal, it 
was dangerous and unpleasant in a very great degree, producing 
cholera and excruciating tormina. 
With regard to those oysters in which the green tint is not 
due to any such deleterious cause, but, on the contrary, rather 
enhances their value as a delicacy, many very different explana- 
tions have been offered of the manner in which that colour is 
acquired. It has been said that the water in the artificial beds, 
remaining stagnant in warm weather, becomes green, and soon 
communicates the same colour to the oysters themselves ; and 
Dr. Johnston, speaking of the French oysters, says that, in order 
to communicate to them a green colour, which, as with us, en- 
hances their value in the market and in the estimation of the 
epicure, they are placed for a time in tanks or “ parks,” formed 
in particular places near high-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 favourable to the growth 
of the green Conferve and Ulve; and with these there are 
generated at the same time innumerable minute crustaceous 
animalcules which serve the oysters for feod, and tincture their 
flesh with the desirable hue. 
In 1820 M. Benjamin Gaillon made a series of observations 
upon this subject, which he communicated to the Académie des 
Sciences de Rouen, and which led him to the conclusion that 
the green colour of oysters is due to the absorption of micro- 
scopic animalcules allied to the Vibrio tripunctatus of Miiller, 
* Dr. Johnston’s ‘ Introduction to Conchology,’ p. 19. 
