THE OVSTER. 199 
the mouth and tentacles, the second enters the liver, and the other 
distributes the blood to the rest of the body. The heart is closely 
beset—embarrassed, we might almost say—by the terminal portion 
of the intestinal canal, the rectum; so much so, indeed, that it 
appears to pass without ceremony into the very midst of the noble 
organ. So do extremes sometimes meet—the spring of life and 
issue of the useless material are close together. 
The é/0od is a colourless, limpid fluid ; it enters the auricle to 
be purified; thence it is driven into the ventricle. This cavity, in 
its turn, contracts, and propels the fluid through the channels 
already described. 
Oysters breathe at the bottom of the sea. The Creator has 
given them organs, by which they are enabled to separate from 
the water the small quantity of air which it contains. They can- 
not live in water which is not aerated, for the oxygen vivifies, 
and renews the active power of the blood. The respiratory organs 
are two pairs of gills, or dranchtie; they are curved, and are 
formed by a double series of very delicate canals, placed close 
together; their appearance is not unlike the teeth of a fine 
comb. This apparatus, like the mouth, is hidden under the fold 
of the mantle. 
Having no head, the oyster can have no dvaiz,; in its place 
there is a ganglion of nerves—a whitish substance, situated near 
the mouth. Out of this originate two nerves, which branch off 
to the regions of the liver and stomach; they again reunite in a 
second similar ganglion, which is placed behind the liver. The 
first ganglion furnishes nerves to the mouth and its tentacles, and 
the second to the respiratory branchiz. The oyster has no power 
of seeing or hearing. The sense of touch appears to be the only 
sensation it enjoys, and that resides in the tentacles of the 
mouth. Its taste, if it have any at all, must be very faint. 
Of all the shelled mollusks oysters seem to have the most 
limited powers. Condemned to a sedentary life, imprisoned for 
ever in their shell, and even without a distinction of sex, they 
cannot have many wants or desires. They must be well-nigh 
apathetic, living in a calm and quiet indifference; and yet these 
mollusks are sociable, and gather themselves together in vast 
numbers; so that, in spite of their feeble intelligence, we cannot 
