XXVI.-ON THE CAUSE OF THE GREENING OF OYSTERS.* 



By M. PuYsi;GUR. 



WITH A SUPPLEMENTARY NOTE ON THE COLORATION OF THE BLOOD 

 CORPUSCLES OF THE OYSTER. 



By John A. Ryder. 



The acquisition of a green tint by the soft parts of oysters has been 

 observed in a great many places; at Mareunes, Pile cFOleron, Cour- 

 seulles, etc., and practical as well as scientific men have long been 

 engaged in trying to discover the cause of this phenomenon. Their 

 observations are scattered through diverse periodical publications, to 

 which I have been obliged to refer, for it was important to determine if 

 their researches were of any real value, inasmuch as none of those yet 

 undertaken seem to lead to correct and indisputable conclusions. 



The first paper upon this subject which I have been able to find is by 

 Gaillon, which was issued in the Journal de Physique, de Chimie et 

 dliistoirc naturelle for September, 1820, tome xci, and was republished 

 with notes by Bory de Saint- Viucent in the Annales generales des sciences 

 physiques, tome vii, Brussels, 1820, pp. 89-94. 



While desiring to be concise, I cannot resist the temptation to cite 

 some passages from the notice by Gaillon. 



******* 



"This green color," says this savant, "is attributed by some to a dis- 

 ease which affects these mollusks." "No," say others, "it is due to the 

 particles (fragments) of green marine plants upon ^^lich they feed dur- 

 ing a part of the spring and autumn." Others simply pretend that 

 the plants cause the water to become green at certain times, and that 

 the oyster absorbs the color from the water and retains it. 

 , After having combated by arguments and objections, which do not 

 seem very convincing, the views which he would reject, Gaillon at once 

 enters upon a discussion of the subject. 



" This malady," he continues, "is it peculiar to the oyster? No; for 

 of other mollusks, some actinians which I placed in this greeuish water 

 were not slow to absorb some of the color. This last observation led 



* Notice siir la Cause du Verdissement des Huitres. Par M. Puys^gur, Sous-commissaire 

 de la Marine, Chevalier de la Legion d^Honneur. Extr. de la Rev. Maritime et Coloniale, 

 pp. 11, \pl. Paris, Berger-Levrault et Cie. 1880. 



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