ELEVENTH ANNUAL MEETING. 75 
found in Spain, of others of a tawny hue in Ilyricum, and of 
black ones at Circeii, the latter being, he says, black both in 
meat and shell. Horace and other writers awarded these -the 
palm of excellence. However, the black appearance may only 
have been due to an abundance of the natural purple pigment 
in the mantles of the animal, which varies very much in different 
forms ; 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 European and Amer- 
ican species, as may often be noticed. 
The most important glandular appendage of the alimentary 
tract of the oyster is the liver. It communicates by means of a 
number of wide ducts with a very irregularly formed cavity, 
which we may designate as the stomach proper, in which the 
food of the animal comes into contact with the digestive juices 
poured out by the ultimate follicles of the liver, to undergo sol- 
ution preparatory to its absorption during its passage through 
the singularly formed intestine. 
If thin slices of the animal are examined under the micro- 
scope we find the walls of the stomach continuous with the walls 
of the great ducts of the liver. These great ducts divide and 
sub-divide until they break up into a great number of blind ovo- 
idal sacks, into which the biliary secretion is poured from the 
cells of their walls. A thick stratum of these follicles surrounds 
the stomach, except at its back or dorsal side. It is not correct 
to speak of the liver of the oyster as we speak of the liver of a 
higher animal. Its function in the oyster is the same as that of 
three different glands in us, viz., the gastric follicles, the pan- 
creas and liver, to which we may add the salivary, making a 
total of four in the higher animals which is represented by a sin- 
gle organ in the oyster. In fact, experiment has shown that the 
secretion of the liver of mollusks combines characters of at least 
two, if not three, of the glandular appendages of the intestine of 
vertebrated animals. There are absolutely no triturating organs 
in the oyster for the comminution of its food; it is simply ma- 
cerated in the glandular secretion of the liver and swept along 
through the intestine by the combined vibratory action of in- 
