Hypertonic Sodium Research Articles

ON THE REVERSIBILITY OF THE HELIOTROPISM OF ARENICOLA LARVÆ BY CHEMICALS

1. At room temperature nearly all Arenicola larvæ in the early swarming stage in normal sea-water are positively heliotropic. At a temperature 10° C. higher (30°-34°) about half of the larvæ become negative to light after about 5 minutes' exposure. At 10° C. lower than room temperature (ca. 12°), about 20 per cent. of the larvæ become negative after about 25 minutes exposure.2. In sea-water made hypertonic by addition of NaCl or KCl some larvæ (20-35 per cent.) become negative.3. In sea-water made hypertonic with CaCl2, MgCl2 or MgSO4, no reversal was observed.4. In hypotonic sea-water, about 90 per cent. of the larvæ reversed their heliotropism; reversal takes place more rapidly the higher the temperature (between 12° and 32°).5. Isotonic solutions of ammonium, potassium, lithium, sodium chlorides and sulphates made in sea-water reverse the positive heliotropism of the larvæ. But isotonic solutions of magnesium and calcium chlorides and sulphates in sea-water do not. The reversing effect of these salts seems, therefore, due to the cations. This suggests an action on the plasma membranes. (cf. the membrane theory of Ostwald-Bernstein).1 The effective order of these cations is Na+<Li+<K+<NH4+6. In artificial sea-water, the positive heliotropism of the larvæ is not noticeably different from that in natural sea-water. A trace of alkali makes apparently no difference.7. Hypertonic sodium and potassium chloride solutions added to the artificial sea-water reversed the positive heliotropism of the majority of the larvæ.8. In sodium-free artificial sea-water, the larvæ became motionless immediately after the treatment (effect of hypotony).9. In potassium-free artificial sea-water, many became negative to light, and remained at the bottom of the negative side of the beaker.10. In calcium-free artificial sea-water, the larvæ became motionless about 15 minutes after the exposure. Magnesium alone, therefore, cannot antagonize the toxic action of sodium and potassium salts.11. In the magnesium-free artificial sea-water, many remain positive to light. This fact may be explained as an antagonistic action of calcium toward sodium and potassium salts which acting by themselves are negativating agents.12. Alcohols (methyl, ethyl, n-propyl, n-butyl) as used by the writer are not favorable as negativating agents at room temperature, though they are good at higher temperature. The higher the alcohol in the series the greater negativating effect it has.13. Most of the larvæ treated with esters, methyl and ethyl acetate, became negative at higher than room temperature.14. Other compounds, chloroform, formalin, ether and saponin, produced little or no reversal while the larvæ were in the solutions, except saponin at higher temperatures.15. Monobasic fatty acids are the best of all chemicals used for this work. The higher the acid in the series the greater negativating effect it has.16. Some narcotics "antagonize" or retard the reversing action of butyric acid.17. The reversing effect of a very weak concentration of butyric acid (.00006 m.) in artificial sea-water is great.18. Hydrochloric and sulphuric acids produce negative heliotropism, almost as well as fatty acids do.19. In producing negative heliotropism, NH4OH is much more efficient than strong bases.20. Arenicola larvæ treated with narcotics become negative after returning into normal sea-water.