Metabolic Reactions of Clams' Tissues to Change in Salinity. I. Ciliary Activity, Narcotic and Cyanide Effects, and Respiratory Quotient

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Abstract
The action of dilute sea water (S. W.) and of isotonic NaCl, upon the oxygen respiration of tissues from the clam (Venus mercenaria) was investigated with differential volumeters. The rate of O2-consumption of gill was inversely proportional to density in S. W. between 1.012 and 1.03. The rate was over 409? higher for gill, in S. W. 1.015, and 129? higher for mantle, but was 159? lower for muscle sections, than in S. W. 1.025. The effect of dilute S. W. upon gill and mantle respiration was probably independent of ciliary activity, which was retarded by dilution (gill). A 479? rise in O2-consumption of gill occurred in isotonic NaCl soln., which was mostly prevented by CaCl2 in the concn. found in S. W. In equal parts of isotonic NaCl and S. W. there was no increase in respiration, which may indicate an antagonism by some ion besides Ca (probably Mg). Cyanide ([image]/1000) markedly inhibited respiration in mantle and muscle; but it did not affect that of gill in summer, and only moderately during autumn. The inhibition was greater in gill and mantle tissues in diluted S. W. The respiratory quotient of the gill was 0.87 in sea water of density 1.025, and 0.94 in S. W. 1.015. From a consideration of these results, and from a review of the work of others upon the osmotic conditions in Lamellibranchs, it seems possible that in V. mercenaria osmoregulation may be involved in the respiratory responses of epithelial tissues (gill, mantle) in dilute sea water.
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