Methods are described for the continuous culturing ofNostoc muscorumand for the manometric measurement of its photosynthesis.N.muscorumrequired a more dilute and more alkaline medium for growth and for measurement of its photosynthesis thanChlorella pyrenoidosa. Although lacking organized chloroplasts,N.muscorumexhibited higher photosynthetic capacity at 25 deg;C. in terms of cell numbers and chlorophyll content thanC.pyrenoidosa. The photosynthetic capacities ofN.muscorumandC.pyrenoidosawere not significantly different on a solids basis. Saturating light intensities, optimum and maximum temperatures, activation energies, induction periods, and inhibition by phenylurethane were similar for photosynthesis inNostocandChlorella. Aerobic induction was not abolished by an atmosphere of pure oxygen, or by glucose feeding.Photosynthesis inNostocwas abolished by exposing the filaments to weakly acidic media, and usually was injured by washing them with neutral or mildly alkaline potassium-free media. The lyotropic series for the prevention of washing injury inNostocwas K Rb NH4, Li, Na. This washing effect is discussed in relation to the chloride effect on the Hill reaction, the magnesium effect onAzotobacterrespiration, as well as the effect of potassium on the bioelectric properties ofNitella, to which it appears related.
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