Mr. A. W. EH. 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, hich 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 effects 
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 
branchiz. 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 observation 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-bearded 
oysters, in England. ‘These have been long exported to various 
countries, where the taste for’such delicacies was more advanced 
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