Show marvelous arv elous life li fe Is I 1 s led by the oyster changes from male to female and back again london the curator of the aqua reum at the london zoo Is astonished to find how little people know about that luscious bivalve the oyster so with the aid of doctor orton head of the british government survey at ply month mouth he writes a romantic biography la to the observer of london the ouster cister starts its life as a free swimming organism keep ng itself afloat and moving in the water tor for about a fortnight by means of the cilia its fairy I 1 11 I 1 e paddles in energetic motion gradually its developing shell becomes heavier the weight becomes too much even for its most strenuous efforts and it sinks to the bottom or imell it touches some solid object on its luck for one can describe it la in no other fashion at this stage de rends its future existence landing on mud or soft sand its doom Is sealed and many millions of oysters in this fashion perish annually amer can experts ways for cheapness and for ease of de tach ment of the developing oysters the american experts have lately used the rectangular cardboard egg holders from egg boxes similarly coated with lime and sand once settled the oyster has literal ly nothing to do but eat and grow its one occupation in life Is to strain gallon callon after gallon of water through its filtering mechanism which retains the minute food organisms and passes them on into the mouth of the animal its one protection against its en amies Is its hard shell and the ability to keep the two halves firmly closed by the adductor muscle crabs how ever can break it open starfish may either pull the shell apart or by means of a convenient arrangement when the eyster oyster Is too big and strong tor for this operation and equally too big to low they may evert the stomach and engulf the unfortunate oyster until at last compelled to open its shells for fresh supplies of oxygen it Is attached attacked weakened and finally destroyed by the alg algest estIve lve juices in its second summer the oyster reaches maturity and it Is with the investigation of this period of its life that doctor orton has been chiefly as soc the oyster Is not a berma herma ph nor Is it propagated by di dl vision vl Ion it Is bisexual but any one oyster does not belong to one sex throughout its life transformation of sex at first maturity the oyster functions as a male 11 within athin six weeks of that time it may be a female car lying a full complement of developing embryos when these last are ready tor for the free swimming stage they are discharged into the water and the par ent its duty done again becomes a male and goes into a resting stage from which it will not emerge until the following summer or possibly a year later than that when the cycle Is again repeated I 1 unlike the eggs of most fish the eggs of the oyster are fertilized within the body of the parent where they are retained until the develop ng embryos of which there may be a milli million on or more have actually reached the form of small oysters they are not however im mediately extruded into the water but first spend an intermediate existence in the mantle cavity of the parent where they may continue to develop actually in water but under fully pro conditions at first unless examined under the microscope they resemble a milky fluid and to those in the trade the oyster Is then known as white sick As the shell develops the mass becomes gray and then dark when the parent oyster Is described as black sick at the end of this stage the young oysters are literally blown into the water thereafter to fend for them selves |