The effect of certain inorganic chloride solutions upon the movement of a soil nematode (Rhabditis terrestris Stephenson), and upon its bodily size

Abstract

1. Worms which had been cultured in media of different osmotic pressures were immersed in concentrated solutions of NaCl, KC1, CaCl2 and MgCl2, and the times of cessation of spontaneous movement noted.2. Worms from ‘normal’ cultures were immersed in a single concentration of each of the above solutions (all osmotically equivalent to 0·51 M NaCl) and the shrinkage curves were determined.3. Worms from ‘normal’ cultures were placed in NaCN and KCN solutions and the subsequent shrinkage on immersion in a concentrated balanced salt solution was measured. From these results it is concluded that cyanide decreases the permeability of the body to water, and also that NaCN enters the body more rapidly than KCN.4. It has been shown that the chloride solutions which produce the greatest effect on the movement of the worms produce the least shrinkage and vice versa. From this it is concluded that the substances investigated can be arranged in order of their rates of penetration approximately as follows: NaCl> CaCl2> MgCl2, KCl.5. It is suggested that the results obtained are more easily explained on the assumption that the rates of penetration of the substances used are controlled by the activities of living protoplasm than by the properties of non-living cuticle.