1. At temperatures above 25° C. small quick contractions of the sphincter of the sea anemone, Calliactis parasitica, occur in response to single electrical stimuli which are normally ineffective.
2. These contractions, though they never become large, increase in size as the temperature rises until they vanish, along with all other responses, between 30 and 35° C.
3. The effect is discussed in relation to the timing of the two processes, facilitation and excitation, involved in the quick response in this animal.