Toxicity of Mercury Ion and Cypermethrin Pesticide to Tetrahymena Pyri-formis
汞和农药安绿宝对四膜虫的毒性

The toxicity of mercury ion and pesticide cy-permethrin to tetrahymena pyriformis was observed in this study according to the method of aquatic toxicology. Results show that the rate of cell division multiplication of tetrahymena pyriformis decreases obviously with the increase of concentrations of mercury ion and the pesticide. The lowest effective concentrations for an observation period of 24h were 0.0001mg/L for mecury ion and 0.01 mg/L for cypermethrin, respectively. The lowest effective concentrations for a 48 h observation were identical to those for the 24 h observation. High concentrations of the chemicals caused deformation, shrinkage, obnormal movement and even death of the cell. The results of individual counting method was tantamount to these of transmis-sivity method for judging toxicity of mecury ion and cypermethrin.