1883.| Zevilogy. 87 
way as O. edulis and O. angulata of the Tagus, which I have been 
able to learn from fresh material from Liverpool, obtained for me 
through the efforts of Professor Baird. Additional investigations 
recently made have served to convince me that the coloration -is 
unquestionably due to a tinction or staining of the blood cells of 
the animal, and that the coloring matter is either derived from 
without or else may be a hepatic coloring principle, which through 
some derangement of the normal metabolic processes of the ani- 
mal, has been dissolved in the lympho-haemal fluids and so been 
taken up by the blood cells or hamatoblasts and given them their 
peculiar color. The blood cell of the oyster measures about 
suo th of an inch in diameter, but varies somewhat in size. It is 
amcebal in behavior to a surprising degree, throwing out pseudo- 
podal prolongations which may even be branched. In a tempera- 
ture abnormal to them at this season, I have had them live ina 
-compressorium, bathed in their own serum, for four hours, during 
which time they exhibited the most surprising activity of move- 
ment, even becoming confluent with one another. The corpuscles 
which have been most deeply tinged appear to have lost their 
amcebal disposition, and when large quantities of green corpuscles 
have been freed from the meshes of the muscular trabeculz of the 
ventricle, they exhibit a rounded form with no disposition to throw 
out pseudopods or to migrate. To this may be due the fact that they 
accumulate in the trabecular meshes on the inner surface of the 
heart and in cyst-like spaces in the mantle. They differ in no re- 
spect from a quiescent, normal, colorless blood cell of the oyster, 
except in color. The hypothesis of tinction which I have pro- 
posed, in no way disposes me to assign a less value to the influ- 
ence of the food as the primary initiatory agency in effecting a 
staining of the internal ends of the cells which form the walls of 
the hepatic follicles. In fact, in certain lots of oysters most affected, 
the hepatic follicles are most deeply stained internally. I have 
aled to prove by spectroscopic research that this substance is 
chlorophyll, and my belief that it is chlorophyll at all, has 
recently been weakened by the fact that specimens which had 
the liver dyed deep green and were affected in other parts 
have shown no disposition to part with their coloring matter 
although immersed in strong alcohol for months, during which 
time it has been changed two or three times. Chlorophyll, 
So eminently soluble in alcohol during all this time, would also not 
be likely to retain its color, as its bright green tint slowly fades 
when in the form of an alcoholic solution. Wide differences are 
observable in the color of the liver of oysters; in some the folli- 
cles are reddish-brown, in others dark-brown, and in “ greened” 
oysters they may be of a brownish-green. In sections these dif- 
erences are very conspicuous. 
. The hypothesis of vegetable parasites, and a most airy one at 
that, seems to me in this case to have no foundation whatever. 
