Abstract
FOURTEEN papers, forming vol. xi. (1917, pp. 360), are issued from the Department of Marine Biology of the Carnegie Institution of Washington. Three papers record observations on the scyphomedusa, Cassiopea xamachana, which is common in shallow water near the laboratory at Tortugas, Florida. This medusa, which thrives well in aquaria, is accustomed in nature to a considerable range in salinity and in temperature, and, having commensal algal cells, is in some measure independent of the oxygen supply of the surrounding water. On removing, by means of two circular cuts, the peripheral region, including the sense-organs, and the central stomach, an annular piece of- tissue is obtained which is paralysed (owing to removal of the sense-organs), but is capable of stimulation by an induction shock until a contraction wave going in one direction is entrapped in it. Such a wave may maintain itself for days with little change of rate provided the temperature, CO3, salinity, and H-ion concentration of the sea-water remain constant. Such rings of tissue provide extremely favourable material for the study of variations in the rate of nerve-conduction in natural sea-water and in artificial sea-water solutions. Dr. A. G. Mayer concludes, after many experiments on these rings, that nerve-conduction is due to a chemical action involving the cations sodium, calcium, and potassium (magnesium is non-j essential), the sodium and calcium combining with some proteid. The high temperature-coefficient of ionisation of this ion-proteid may account for the high temperature-coefficient of the rate of nerve-conduction.
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Marine Biology. Nature 100, 253–254 (1917). https://doi.org/10.1038/100253b0
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DOI: https://doi.org/10.1038/100253b0