0STBEAM3. 
327 
displayed, man, in his reckless and wasteful gluttony, has all hut 
Seated Nature. A tyro can compute how many individuals a hank 
oysters reckoned at twenty thousand would produce, at the rate of 
tw o millions, or eight hundred thousand as other authorities assert, 
; l '°m each one annually, and it will amount to an incredible number — 
1,1 fact, each would multiply itself by millions in three years ; and yet, 
flanks to our improvident management, they get scarcer every year. 
1'he spawning season is usually from the month of June to the end 
°f September : during this season the oysters deposit their eggs in the 
fol ds of the mantle. During the period of incubation the eggs remain 
Grounded by mucous matter, which is necessary to their develop- 
ment, the whole having the appearance of a thick cream— this milky 
a Ppearance being due to the accumulated mass of ova surrounded by 
mucus : this mass undergoes various changes of colour while losing 
lts fluidity, becoming successively yellowish, greyish, brown, and violet, 
a condition which indicates the near termination of the embryo state, 
^° r the oysters do not, like many other inhabitants of the sea, leave 
ova ; they incubate them in the folds of their mantle, and only 
^charge them when they can live without the maternal protection, 
^othhg is more curious to witness than a bank of oysters at the 
^Pawning season. Every adult individual of which it is composed 
tlu ’0Ws out its phalanx of progeny. A living dust is seen to exhale 
r °m the oyster hank, troubling the water and giving it a thick cloudy 
a Ppearance, which disseminates itself little by little in the liquid, until 
lt Adipates and loses itself far from its locus of production. The spat 
18 8 °ou scattered far and wide by the waves ; and unless the young 
°yster finds some solid body to which it can attach itself, it falls an 
| llev i table victim to the larger animals which prey upon them. In 
ds its infant state, when it has just left the protection of tho parent 
le U, the microscope reveals the young bivalve, with its shell perfect, 
av *ng an apparatus which is also a swimming pad, ready to 
■C-bere to the first solid body which the current drives it against. 
. 8 pad or cushion (which is represented in Fig. 129) is fur- 
|J ls Aed with vibratile cilias, disposed round the young shell. Aided 
y ffle powerful adductor muscles, with which it is also provided, this 
^fliion is projected through the water at the will of the young 
ll 'Mutant, which has every facility for the purpose : it is even said to 
about near the mother, before final dismissal from the maternal 
