Abstract
It is always able to induce Mactra veneriformis to discharge the reproductive substances by the injection of the isotonic aqueous solution of KC1 into ist visceral cavity. Mactra discharges the reproductive substances immediately or in a few minutes after the injection. It reaches the maximum discharge soon after the beginning of its reaction, and afterwards decreases gradually the quantity. In some cases the duration of discharge lasted more than 2 hours. Less than 1.5cc of the isotonic solution of KC1 is sufficient to induce the discharge. No distinct relation can be found between the size of bivalve and the least amount of KC1 solution necessary for the induction of the discharge. The female, however, has the tendency of the discharge by the injection of less amounf of KC1 solution than the male reacts.
The neutral K-salts such as KBr, KNO3, K2SO4 are all effective to induce the discharge, while CaCl2, MgSO4 and sea water are not so much effective as K-salts. The results of my experiment suggest that the K-contracture of gonad muscle fibres, caused by the injection of K-salt solutions, seems to induce in the main to discharge the reproductive substances of Mactra.
