Induction of the thigmotaxis in Paramecium caudatum

Induction of thigmotaxis in Paramecium caudatum was examined. We succeeded in the induction by changing the ionic concentration and the Ja-value ([K+]/[Ca2+]1/2) of the surrounding medium. P. caudatum showed thigmotaxis stably in the solution containing a relatively high ionic concentration but a lower Ja-value. We found that the Paramecium cell touched the object with the tip of its oral groove and the cilia touching the object scarcely beat when the organism showed thigmotaxis.