@article{oai:ir.kagoshima-u.ac.jp:00004845,
 author = {WADA, Seiji},
 issue = {2},
 journal = {鹿児島大学水産学部紀要=Memoirs of Faculty of Fisheries Kagoshima University},
 month = {2016-10-28},
 note = {Two species of pearl oysters, Pinctada maxima and P.fucala, were mainly used as materials. When gametes obtained from the excised gonads are employed, fertilization is never achieved in the former and usually fails in the latter form. If, however, the eggs which had been kept for a while in an ammoniacal sea water with around 0.5×10^{-3}NNH_3, were inseminated in the hyperalkaline sea water, fertilization was readily accomplished, and a normal development ensued if the eggs were transferred to plain sea water shortly after the fertilization. In the case of P. maxima an exposure for about half an hour to ammoniacal sea water was necessary to make the eggs fertilizable, while P. fucala eggs could become fertilizable in a few minutes' exposure to the hyperalkaline medium. The sperm, which were very slightly moving when released in sea water, became intensely active and obtained fertilizing capacity when suspended in ammoniacal sea water. It is concluded that ammonia induces an increase in physiological maturity in both eggs and sperm and thus facilitates the fertilization. Hyperalkaline sea water with NaOH or KOH in some cases showed an improving effect on the fertilization of P. fucata eggs. This effect, however, is barely recognizable in P. maxima. Ammonium chloride-sea water, not only with a hyperalkaline but also with a normal pH value, induced the nuclear breakdown of eggs and a marked increase in sperm motility just as ammoniacal sea water does, resulting in an improvement in the rate of fertilization. These facts suggest that the facilitation of fertilization by ammoniacal sea water is mainly caused by a specific action of ammonia which is known to very readily penetrate a cell. The use of ammoniacal sea water is applicable to other forms of pelecypods where an ordinary method of artificial fertilization will fail. The method, which was first developed by the present writer some twenty years ago, is now being adopted in a practical propagation of two forms of economically import ant pearl oysters, Pteria penguin and Pinctada maxima.},
 pages = {92--108},
 title = {Studies on the Fertilization of Pelecypod Gametes I : Increase on Maturity and Accomplishment of Fertilization of Pearl Oyster Gametes in Ammoniacal Sea Water},
 volume = {12},
 year = {}
}