72 FISH-CULTURAL ASSOCIATION. 
quotation, that it is not impossible for diatoms to be the cause 
of the green tint in oysters, which, let me remark, is very nearly 
that of some pale green forms of those organisms which I have 
observed in water from oyster coves where I have conducted 
microscopic studies. Besides, sections through the intestine of 
the oyster frequently reveal the fact that diatoms must have con- 
stituted a very large proportion of the food of the animal, judging 
from the profusion of the empty frustules of these minute plants, 
which are very often found together with the indigestible, earthy 
and silicious particles with which the alimentary canal is 
packed. 
I find the liver to be normally of a brownish red color in both 
the American and European oyster, sometimes verging toward 
green. When the flesh or gills of the animal is green, the liver 
almost invariably partakes of this color, but in an intensified 
degree. The green stain or tincture appears in some cases to 
have affected the internal ends of the cells which line the folli- 
cles or ultimate saccules of the liver. This color is able to sur- 
vive prolonged immersion in chromic acid and alcohol, and does 
not allow carmine to replace it in sections which have been 
stained with an ammoniacal solution of that color, the effect of 
which is to produce a result similar to double staining in green 
and red. The singular green element scattered through the 
connective tissue remain equally well defined, and do not take 
the carmine dye. I at first believed these to be parasitic vege- 
table organisms, and I also supposed I saw starch granules in 
them, which physical tests with an iodine solution failed to 
confirm. These large and small green granular bodies in the 
connective tissue and those close to the intestinal wall, as well 
as those in the heart, I find present in fewer numbers in white- 
fleshed oysters, but simply with this difference, that they are de- 
void of the green color. It is evident, therefore, that they can 
not be of the nature of parasites, though the color is limited to 
them, only the surrounding tissue, except in the region. of the 
heart, appearing .of the normal tint. This condition of the 
specimens observed by me does not, however, disprove the pos- 
sibility, of the occurrence of vegetable parasites in the oyster, 
where there is as much, or perhaps more, likelihood of their 
