OBSERVATIONS ON REPRODUCTION, PREMATURATION, AND FERTILIZATION IN SABELLARIA VULGARIS

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Abstract
This polychaete annelid occurs abundantly at Woods Hole and the gametes are available throughout the summer. They shed immediately after removal from their sand tubes. The eggs undergo at once peculiar prematuration changes. Reproduction, prematuration and fertilization processes in the living egg are discussed. The plane of the first cleavage bears no fixed relationship to sperm entrance point and passes to one side of the animal pole as determined by the position of the polar bodies. Eggs may be fertilized after 7 hrs. but the functional life of the sperm is shorter. Old unfertilized eggs may stratify into 3 zones. Increase of pH, shaking and standing may cause polar body formation.