BULLETIN OF THE UNITED STATES FISH COMMISSION. 415 



indicate that the color was probably absorbed from the food of the ani- 

 mal, which, as we know, consists largely of vegetable matter. The 

 green coloration of the kver, I am convinced, is not due in such in- 

 stances to a hepatic secretion, which, by the way, is not normally of 

 this color in the oyster. It is not im})robable that the blood-cells im- 

 bibing the color from the tinged nutritive juices transuded through 

 the walls of the alimentary canal acquired the color of the food which 

 has been dissolved by the digestive fluids. How to account for the 

 accumulation of the green cells in the heart and in cysts in the mantle 

 is also a difficult question, unless one be permitted to supr)ose that the 

 acquisition of the green color by the blood-cells is in reality a more or 

 less decidedly diseased condition, for which we again have no ground 

 in fact, since the green oysters are apijarently in as good health as the 

 white ones. They are found "fat" or "poor," just as it may have hap- 

 pened that their food was abundant or the reverse. 



If it be objected that the green color indicates an unhealthful condi- 

 tion of the animal, it may be stated that still other color variations of 

 the flesh have fallen under my observation recently. What I allude 

 to now is the yellowish, verging towards a reddish cast, which is some- 

 times noticed in the gills and mantle. This, in all probability, like the 

 green color, is due to the reddish-brown matter which is contained in 

 much of the diatomaceous food of the animal. Mr. J. M. Carley has 

 also called my attention to these variations, and was inclined to attrib- 

 ute it to the soil in the vicinity of the beds. But if the classical writers 

 are to be trusted, to the green, yellow, and white fleshed sorts, we must 

 add red, tawny, and black fleshed ones. Pliny tells us of red oysters 

 in Spain, of others of a tawny hue in Illyricum, and of black ones at 

 Circeii, the latter being, he says, black both in meat and shell. Horace 

 and other writers awarded these black oysters the i^alm of excellence 

 (O'Shaughnessy). However, the black api^earauce may have been due 

 to an abundance of the natural purple pigment in the mantles of the 

 animal, which varies very much in different species ; some, judging 

 from the dark purple color of the whole inside of the shell, must have 

 the whole of the mantle of the same tint. The amount of color in the 

 mantle, especially at its border, varies in local varieties of both the 

 American and European species, as may often be observed. 



As to the culinary value of green oysters my own experience has 

 indicated that as far as their taste is concerned they are not perceptibly 

 inferior to the white-fleshed ones. While in Islew York recently I was 

 enabled, through the kindness of Mr. J. M. Carley, to test the com- 

 parative eating qualities of the two sorts pretty satisfactorily. When 

 stewed, no difierence was perceptible to the taste, and not the slight- 

 est suspicion of an acrid metallic flavor could be detected, such as 

 would have undoubtedly been perceptible had copper been present in 

 poisonous quantities. Professor Leidy about the same time tried a sim- 

 ilar experiment with the same result, concluding that the difl'erence in 



