76 



at any rate, mechanically retained on, or in the body of 

 the Oyster, probably as a basic carbonate. 

 ' The analytical results were as follows : — 



* The total copper present is almost nine times the 

 normal quantity, and about half of this is easily removed 

 by dilute acid. It is quite likely that the remainder is 

 partially or wholly simply entangled in the food passages 

 of the Oyster, and that the green colour may be due to 

 some other cause than this mechanically retained copper, 

 as suggested by Herdman.* Mr. G. C. Bourne, indeed, 

 regards it as due, in some Falmouth Oysters, to a green 

 desmid upon which the Oysters feed in quantity. 



' The occurrence of copper under such conditions is due 

 to the locality, and may quite possibly attain injurious 

 proportions, for the Oysters were obtained from a creek 

 which is locally supposed to bring down copper, and the 

 mud of which was found by Thorpe to contain 0'148 per 

 cent, of copper. Normal sea-water contains such an 

 excessively small quantity of copper that it was not found 

 possible to detect its presence, even electrolytically, in a 

 litre of sea-water, after concentration. 



' The green leucocytosis already referred to was first 

 noticed by Herdman and Boyce in American Oysters 



* "Nature," 1897, p. 366. 



