Abstract
In Mytilus edulis spermatozoa taken from its testis are active in sea water and powerful in fertilization, while eggs taken out of its ovary would not be fertilized by any spermatozoon.
The ovarian eggs of non-spawning mussel are always inmature and still in germinal vesicle stage, whereas those of spawning one lose already their germinal vesicle and are fertilizable in high percentage.
The eggs spawned naturally are all mature in stage, and those taken from oviduct of spawning mussel are also sinilar in nature as the spawned eggs. A mussel with inmature eggs is stimulated electrically and discharged abundantly the mature eggs in an hour, on an average. Then the maturation must be taken place in the ovary in short time.
