MICRURGICAL STUDIES IN CELL PHYSIOLOGY. III. TgE ACTION Or C02 AND SOME SALTS OF NA, CA, AND K ON ~rHE PROTOPLASM OF AMEBA DUBIA.* BY PAUL REZNIKOFF AND ROBERT CHAMBERS

The first paper (1) of this series described the action of the chlorides of Na, K, Ca, and Mg on the protoplasm of Ameeba dubia as determined by mlcrurgical technique. A study of the effect of other salts of some of these cations forms the basis of this report. 1 Among those tested were a few which are often employed in preparing buffer solutions and some of general physiological interest, particularly solutions containing phosphate, borate, lactate, acetate, bicarbonate, carbonate, and CO~. The details of the apparatus, its manipulation, and the terminology used have been fully described in a previous publication (1) to which the reader is referred. Immersion Experiments.--When amebic are immersed in toxic concentrations of any of the Na salts used in these experiments, the same effect is obtained as that found with NaC1 (1), viz., rounding, quiescence, and sinking of the heavier granules. In general, the toxicity of the phosphates depends upon the relative amount of Na in the salt (Table I). The only exception to this is the marked toxicity of NaH2PO4 in concentrated solutions due to the acidity of this salt (1). Mkalinity alone, as has been shown previously (1), is not a factor in the production of toxic effects. The phosphate ion may be a factor in contributing to the toxicity of these salts, since even in