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of their bade doors for centuries on end. Roman emperors and 

 Aztec emperors had them rushed to their tables, packed in snow, 

 by relays of runners on horseback or on foot. The Romans placed 

 their major settlements in England by the best oyster beds, and 

 boasted of the fact. 



The oyster itself usually begins life as a male but then 

 changes to a female and usually back again, sometimes several 

 times. These bivalves breed, in this area, from April to October, 

 during which time they exude a milky fluid. This is either the 

 milt of the male or the countless millions of minute eggs of the 

 female, one of which can give rise at one time to up to sixty 

 million eggs. Both milt and eggs are merely let out into the sea. 

 where the sperms find the ova. After fertilization the usual 

 procedure of cell division goes on until in only a few hours there 

 is formed a minute spherical body covered with even minuter 

 hairlike processes called cilia. These thrash about fairly system- 

 atically and keep the little thing afloat so that it is moved away by 

 currents. Eventually it starts to grow two tiny shells; and when 

 these get heavy enough, they cause the animal to sink to the 

 bottom, where it immediately attadies itself to some firm object 

 for life. This stage is called "spat." and by that time the oyster 

 is pretty well organized internally for pumping water through 

 itself both for food and for oxygen; but it is very sensitive to fine 

 silt in the water and must be raised off the bottom. This is the 

 principal reason for returning the empty shells from our tables 

 to the sea — so that the little spat can perch up in clean water. 

 The cilia have by now retreated into the body of the animal, but 

 they continue to thrash, so driving a constant stream of water 



into the gut and around the gills — at the rate of about fifty gal- 

 lons a day for an average Bluepoint. incidentally! 



The animal itself is enclosed in a mantle, and it is the edge of 

 this that secretes the shell by a most complicated process, part 

 internal through the blood stream and part external by a sort of 

 "electrolysis" of the water in which many salts are dissolved. 

 The shell grows from the inside, layer upon layer, and if some 

 particle of grit or irresolute small creature gets under the mantle 

 and causes irritation, the oyster starts to build a little shell round 

 it to smooth off its rough edges. Thus are pearls bom. The oyster. 

 I fear me. is not necessarily a very clean feeder; in fact, it can 

 be an exceedingly filthy one from our point of view. Never- 

 theless we almost all eat it. Why this should be so is obvious, for 

 it undoubtedly has a very pleasing taste, full of saltiness. Oysters 

 are ready for the table in about two years, but they seem to be 

 able to live to a very great age. 



The oysters and the clams have, as a matter of fact, played 

 almost as great a part in the formation of this delta as the river 

 itself, and they are a somewhat prominent feature of its existence 

 today. They will continue to be so in the future unless man once 

 again plays havoc with ecology. So far. for once, he is doing the 

 right thing in cooperation with nature, but still the oysters are 

 diminishing drastically. This is partly due to pollution, mostly 

 by oil which, though it has not been proved to kill them, gives 

 them a taste that is just not acceptable to humans. Man has lived 

 with the oyster for endless millennia; and perhaps he can still 

 come to a mutually satisfactory accommodation here too. despite 

 his need for petroleum. 



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