THREE FIGURES
I n a preceding paper (Schneyer, '51) it was pointed out that low concentrations of calcium and phosphate salts together (Ca 10 mM. ; PO, 2.5 mM.), but not separately, increase the intensity of bacterial luminescence throughout the viable temperature range and that this effect may be au,grnented b j ~ tlie application of high hydrostatic pressure (400 atmospheres).
In the present study, the effects of potassium salts on bacterial luminescence intensity have been investigated. Johnson and Harvey ('38) have reported an inhibitory effect of potassium on this system a t temperatures near the optimum for luminescence. The present work corroborates the findings of .Johnson and Harvey for this temperature range. It is now found, however, that the inhibiting effect of potassium decreases with a reduction in temperature from any point above the optimum and, in fact, becomes a stimulating effect at still lower temperatures. This stimulating effect resemblcs the Ca-PO, effect in that it is pressure sensitive. Furthermore, This investigation was carried on as part of a project a t Xew York Univer-sit>-directed by Dr. Dugald Brown and aided by a grant from the Cinchona Products Institute, Inc.