34 



Prof. R. Boyce and Dr. W. A. Herdman. 



vessels we found the accumulations of leucocytes. From 120 oysters 

 we chose the six greenest and the six whitest. Dr. Kohn analysed 

 these two sets of six for us, and found that the green contained 

 between three and four (3 - 7) times as much copper as the white. This 

 shows that it is not merely a redisposition in the body of the copper, 

 due possibly to the hsemocyanin, but that there is an absolute increase 

 in the amount present in the body. 



We also found that the greenest parts of the body contained far 

 more copper than corresponding tissues which had no green deposit 

 in them. Not only then do these green oysters contain a largely 

 increased amount of copper, but we have also shown that the copper 

 coincides in its distribution with the green leucocytes, and, conse- 

 quently, we regard the copper as the cause of the green colour. We 

 then passed on to a more minute examination of the pigment and to 

 histo- chemical reactions. 



Chemical Reactions. 



The Green Colouring Matter. — The greenest portions of the green 

 oysters were snipped out and dried on the water bath. The dried 

 powdered residue was treated with alcohol, ether, chloroform, 

 benzene, turpentine, xylol, but these reagents failed to extract the 

 colouring matter ; we concluded, therefore, that the pigment was not 

 of the nature of a lipochrome. On the other hand, the pigment was 

 readily soluble in dilute acids and in alkalis ; the addition of am- 

 monia gave rise to a distinct bluish tint, and fresh pieces of the green 

 oysters reacted instantly with ammonia, with the formation of a 

 beautiful blue. 



We next determined whether the pigment was due to iron or 

 copper. The dried residue treated with dilute hydrochloric acid 

 and potassic ferrocyanide gave a marked red reaction, thus indi- 

 cating the presence of copper, and it was then found that very 

 small quantities of the green colouring matter treated with dilute 

 hydrochloric acid were sufficient to produce a well-marked deposit 

 of metallic copper upon polished iron. In several instances a 

 deposition of copper occurred when a piece of polished iron was 

 laid upon a green patch on the surface of the mantle of a fresh 

 oyster, dilute hydrochloric acid having been previously used to 

 moisten the mantle. Control experiments were made with the 

 whitest portions of the American oysters and with natives, and 

 traces only of copper were found. These results have been also 

 quantitatively controlled by Dr. Kohn. 



A series of histo-chemical reactions were then carried out. For 

 the purpose the oysters were hardened in absolute alcohol, and 

 pieces were then imbedded in paraffin, great care being taken that 



