122 SEA-SHORE LIFE 
of the body, as two sheets on each side, near the mid-dorsal line, 
and which lie free in the space between the mantle and the body 
of the oyster. The digestive tract is 
much coiled and twisted, and the mouth 
of the oyster is placed close to the 
hinge at the narrow apex of the shell, 
where it is surrounded by curtain-like 
lips. 
There is a well developed stomach 
which often contains a glistening, gela- 
tinoas, rod called the ‘“‘crystalline style.” 
The function of this is unknown, al- 
though it may possibly represent stored 
up nutrient material. 
The large green-colored liver sur- 
Fug. 80; AMERICAN ovstEér,  vounds the stomach into which it 
empties, while the reproductive organs 
surround the coiled intestine, and are very large during the 
warmer months when the oysters are spawning. 
A full-grown female oyster will produce about 9,000,000 eggs, 
each being about one-five-hundredth of an inch in diameter. The 
eggs are cast out into the water through the oviducts which open 
into the gill cavity on both sides of the body below the adductor 
muscle. They then develop into little free-swimming larve which 
swim rapidly through the water by means of their hair-like cilia. 
The shelts then appear upon the sides of the body, and when about 
one-eighth of an inch wide the creature settles to the bottom with 
its left side down, and there remains throughout life. 
The true heart of the oyster is bulb-like in shape, and lies 
within a delicate translucent sac close to the inner side of the great 

adductor muscle. It pulsates slowly, and pumps blood from the 
gills to other parts of the body. Growth is rapid at first, for 
under favorable conditions the little oyster, or “spat,” as it is 
called, may become an inch across its shell in seven weeks, and 
two inches in three months. 
The oysters feed upon a great variety of minute organisms, 
such as simple unicellular plants and animals, and small marine 
larve. The gills are covered with waving cilia, which create a 
