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IX.— MICRO-CHEMISTRY OF THE GREEN OYSTERS. 
(Sa- Plates VIL and VIII.) 
The following are the details of the histo-chemical investigation of the pigment 
of the green American oysters with the leucocytosis. The green pigment is insoluble 
in boiling alcohol, ether, chloroform, xylol, and other fat solvents ; it is soluble in dilute 
acids and alkalies. The addition of potassic ferrocyanide to sections containing the green 
colouring matter, or to the leucoc} tes themselves, gives a red reaction, indicating the 
presence of copper ; but the reaction can be most readily obtained by the addition of a 
small quantity of 5 per cent, hydrochloric acid to the potassic ferrocyanide. Ammonium 
hydrogen sulphide gives also an immediate reaction with the green pigment. Ammonia 
strikes a beautiful blue wherever there is green in marked quantity. It was also found 
that pure hajmatoxylin is an extremely delicate test, giving an immediate blue reaction in 
exceedingly dilute solution. Previous treatment of the green colouring matter by 3 per 
cent, nitric acid in alcohol prevented these reactions, and subsequent treatment with 
acidulated potassic ferrocyanide resulted in a very faint Prussian blue colouration of the 
tissue generally (marking out especially the nuclear zone in any epithelium present). We 
concluded that there was no organic iron present in the leucocytes, that the leucocytes 
which form the green patches contain a considerable quantity of copper, and that, just as in 
the case of iron, as shown by Professor Macallum, pure hematoxylin is a most delicate 
test for copper, but that great care must be taken to ascertain by other reagents which 
of the two metals is present. 
Very numerous tests were made with the blood obtained from white oysters, and 
micro-chemical reactions revealed in some instances faint traces of copper. Haemocyanin 
has been described in the blood of various Molluscs, and apparently in the blood of the 
oyster. We have examined numerous samples of blood taken from the white oyster, but 
have failed to get any blue colouration on exposure to air. In the green oysters a very 
faint blue colour has been noticed in some cases on exposing the blood to air. 
To demonstrate the presence of copper in the green leucocytes collected in the 
vessels, the tissues may be examined fresh or after hardening. 
Fresh Blood.— By means of a fine pipette the green corpuscles are removed from 
the heart or other blood space they have collected in, and placed on a cover slip and 
allowed to dry. The dried film, which has a green tint, is then treated with the clear 
dilute ha;matoxylin solution, and at once assumes a deep violet colour. Similarly, with 
