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 1' Academic des Sciences' for 1841, "On sait combien les 

 explications donnees jusqu'^ ce jour sur la coloration des huitres 

 laissent encore k desirer." The object of this paper is to prove 

 that the green colour is due to an animal matter which must he 

 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 branchise. 

 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 colouring 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 

 green 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 

 branchise 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 



