EXPLANATION OF THE PLATES. 59 



PLATE V. — continued. 



Fig. 5. — Section showing external surface of mantle of Nieuport oyster, showing eosinophilous cells 



passing outwards (Zeiss, apochr. 1.5 mm.). 

 Fig. 6. — Transverse section of pallial tentacle of Dutch oyster, showing eosinophilous cells (Leitz, obj. 7). 

 Fig. ?• — Section of internal surface of mantle of American oyster, showing eosinophilous cells (Zeiss, 



apochr. 1.5 mm.). 

 Fig. 8. — Another section of the same, to show the haematoxylin reaction in the eosinophilous cells. 

 Fig. 9. — Large amoeboid granular green leucocytes from the surface of gill and mantle in American 



oyster, with the green leucocytosis, bedded at Fleetwood. The four marked b were from the 



blood, the rest from the surface (Zeiss, apochr. 1.5 mm.). 

 Fig. ID.- — Leucocytes lying between the liver tubules stained with pure haematoxylin (Zeiss, x's). 

 Fig. IX. — Transverse section of a gill filament of green "native " from Roach River (Zeiss, apochr. 1.5 mm.). 

 Fig. 12. — Section of the liver of an American oyster with the green leucocytosis, showing the hasma- 



toxylin reaction given by the leucocytes ( x 60). 



PLATE VI. 



ILLUSTRATING THE GREEN LEUCOCYTOSIS IN AMERICAN OYSTERS. 



Fig. I. — A healthy well-grown "East River" American oyster. 



Fig. 2. — The same with shell valve removed from right side, to show the nearly colourless mantle. 



Fig. 3. — A similar American oyster (from Liverpool market, May 17, 1897) with left valve removed, 



to show the green leucocytosis. Engorged green blood channels are seen over the viscera 



and on the mantle edge, and the auricles of the heart are filled with green leucocytes. 

 Fig. 4. — Left side of another similar oyster (Liverpool market. May 18, 1897), where the pallial blood 



channels are very completely injected with green leucocytes. 

 Fig. 5. — Group of Portuguese oysters {Ostrea angulaia), one of which is opened to show the green 



leucocytosis (July 1897). 

 Fig, 6. — ^An American oyster {O. virginicd) re-bedded at Fleetwood, to show a completely green mantle 



(March 30, 1897). 

 Fig. 7. — Another, to show a completely green heart and a bright patch on mantle over viscera. 

 Fig. 8. — An English oyster {O. edulis) from Falmouth (July 3, 1897), to show the ventricle of the 



heart completely green, and the auricles brown. 

 Fig. 9. — Small Dutch oyster (C>. edulis), to show green spots scattered over the mantle and adductor 



muscle (July 26, 1897). 



PLATE VII. 

 ILLUSTRATING THE COPPER REACTIONS IN GREEN OYSTERS. 



Fig. I. — Part of the mantle of a green American oyster (May 27, 1897) showing the engorged blood 



channels and smaller blood spaces in the connective tissue, coloured red-brown after treatment 



with potassium ferrocyanide (Zeiss, 35 mm.). 

 Fig. 2. — Two ventricles of American oysters, one {B) green and one {A) colourless, shown fresh and 



also after treatment with potassium ferrocyanide. 

 Fig. 3. — Preparation of blood of green oyster, after treatment with potassium ferrocyanide, to show 



some of the leucocytes coloured red (Zeiss, obj. D). 



