Mr. A. W. E. O'Shaughnessy on Green Oysters. 227 



a detailed account of the experiments made by Prof. Bizio with 

 a view to prove this assertion. These experiments, he tells us, 

 were begun in June and continued till the month of September ; 

 they appear to have been conducted with great care and precision, 

 and we would refer those anxious to pursue the investigation of 

 this curious and interesting subject at greater length than we 

 have space to do at present to Prof. Bizio's paper, which will be 

 found in the fourth volume of the 'Transactions^ of the above- 

 named academy. 



Suffice it to say that ammonia, which was one of the principal 

 tests employed by M. Valenciennes in his experiments, is also 

 the agent on which Prof. Bizio most relies; and the results 

 which the latter obtained certainly go to prove that the eflFects 

 recorded by M. Valenciennes as having been produced by am- 

 monia on the coloured portions of the oyster, were, in part, due 

 to the presence of copper. 



It is remarkable that, while M. Valenciennes particularly men- 

 tions the presence of the colouring matter in the intestinal canal 

 and liver of the oyster, Prof. Bizio's remarks refer only to the 

 branchiae. Whether he would imply that the green colour, 

 wherever it shows itself in the oyster, is due to the presence of 

 copper, is a query we are not prepared to answer, but should 

 like very much to have answered for us, as, bearing in mind the 

 cases at Rochefort, we cannot but think this green-oyster ques- 

 tion rather a serious one. 



Fortunately there appears to be very little call for green 

 oysters in the English markets, and the great bulk of them are, 

 we believe, shipped over to France. Perhaps it is a good thing 

 they are so sparingly appreciated in this country. 



It is singular that so little should be definitely known of the 

 cause of a phenomenon which takes place in a creature so easily 

 accessible to obseiTation as the oyster. However, public atten- 

 tion has lately been so frequently drawn to this " illustrious bi- 

 valve,^^ that we have no doubt there will soon be some new light 

 thrown upon this subject. We understand that Mr. Frank 

 Buckland, in reply to a question addressed to him by the House 

 of Lords some time since, stated that a professional chemist, to 

 whom he had submitted specimens of the green oyster, had 

 already found out the true cause of the coloration. 



This, whatever it be, does not seem, however, to have been as 

 yet made public. Mr. Buckland himself seems to incline to the 

 opinion that a growth of green weed of some kind or other du- 

 ring certain times of the year only is the cause. It is now well 

 known that we have real green oysters, or rather yreen-hearded 

 oysters, in England. These have been long exported to various 

 countries, where the taste for such delicacies was more advanced 



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