ON THE MECHANISM OF THE ACTIVITY RHYTHM OF THE SEA-PEN, CAVERNULARIA OBESA VALENCIENNES

Abstract

Efforts have been paid in the present experiments to clarify the mechanism of the expansion-contraction rhythm of the sea-pen. Results are summarized as follows: (1) The hydrogen ion concentration of the body fluid at the beginning of expansion was slightly lower at higher temperatures in the regular rhythm as well as in the case of omission of an expansion. (2) Injection of alkalized, acidified or natural sea water or saline solution induced the contracted colony to expand to a certain extent. (3) Injection of alkalized sea water did not make the expanded colony contract. (4) The expansion-contraction rhythm was affected by both the injection of alkalized sea water and the mechanical stimulation. As far as the results obtained are concerned, it is concluded that the rhythmic behavior of the sea-pen is under the control of a time-keeping mechanism independent of the rhythmic behavior itself, and that the mechanism is susceptible in this sea-pen to influences from the inside and outside.