( 30 ) 



IX.— MICRO-CHEMISTRY OF THE GREEN OYSTERS. 



(See Plates VII. 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 leucocytes 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 hematoxylin 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 haematoxylin 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. Hsemocyanin 

 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 haematoxylin solution, and at once assumes a deep violet colour. Similarly, with 



