226 Mr. A. W. E. O’Shaughnessy on Green Oysters. 
now recognized as being of a vegetable nature. The species 
ostrearius appears in the last edition of Pritchard’s work on the 
Infusoria as a Navicula. 
In spite of the detailed observations and experiments of M. 
Gaillon, we find M. Valenciennes remarking, at the commence- 
ment of a paper on the same subject at the ‘Comptes Rendus 
de Académie des Sciences’ for 1841, “On sait combien les 
explications données jusqu’a ce jour sur la coloration des huitres 
laissent encore & désirer.” The object of this paper is to prove 
that the green colour is due to an animal matter which must be 
quite distinct from all green organic substances hitherto known. 
M. Valenciennes says that the only externally visible organs 
which display this colour are the four leaflets of the branchie. 
On lifting the upper part of the mantle, the inner surface of 
the labial palps alone appear coloured; and on extending the 
examination to the internal organs, the intestinal canal beyond 
the stomach is seen to be of a bright green colour; the liver is 
of a blackish green tint instead of the usual red; but neither 
the muscles, nerves, heart, nor even the juices of the body exhi- 
bit any change of colour. 
According to M. Valenciennes, the colourmg matter offers 
nothing remarkable when viewed under the microscope; but 
when examined chemically it is found to possess certain proper- 
ties which led him to the conclusion above quoted. His ob- 
servations were made on the large green oysters of Marennes ; 
but he says that like results have followed the application of 
the same chemical tests to the so-called green oysters of Ostend, 
which are less strongly coloured. 
M. Dumas made some experiments in order to discover if the 
grees matter might not owe much of its colour to Prussian blue. 
The result is stated to have been in the negative. However con- 
clusive the observations of M. Valenciennes may appear, Prof. 
Bizio, in a memoir read before the Institute of Venice in the year 
1845, calls attention to the fact that some ten years previously 
he demonstrated the existence of copper in the branchial organs 
of the Ostrea edulis, at the time when a similar discovery was 
made with reference to the spire of the Murex. He says that he 
then hinted at the possibility of the green colour observed in the 
branchiz being the effect of the copper which enters into the 
composition of that organ, and that he has been confirmed in 
that opinion by these very experiments of M. Valenciennes, 
which, he says, tend to make it evident, to anybody who knows 
anything about copper, that the colouring matter is neither more 
nor less than that metal combined with, and disguised in, the 
organic substance of the oyster. 
It might be somewhat tedious to the reader were we to give 
