Letter | Published:

Responses of Cerianthus to Stimulation

Naturevolume 180pages13691370 (1957) | Download Citation



Cerianthus responds to a single condenser shock by a rapid contraction of tentacles and column. The response is symmetrical no matter where the shock is applied, from aboral end to tentacle tips, is propagated with a velocity of 1–2 m.sec., and is independent of the strength of the stimulus above threshold. The response is followed by an absolute refractory period of 60–70 m.sec. at 22–23° C. and a relative refractory period up to 200 m.sec. after the stimulus. For stimulation of either tentacles or column a threshold at twice the rheobase was obtained by discharge of a 0.05 µF. condenser through a total electrode-plus-preparation resistance of 3,000 ohms, thus giving a capacitance-resistance value of 0.15 m.sec. and chronaxie of 0.05 m.sec. Non-polarizable zinc–sulphate–zinc–agar glass tube electrodes of 0.5 mm. orifice diameter were used. With the same apparatus the chronaxie of the column through-conducting system of Naples specimens of Calliactis was 1.0 m.sec. Hill's1 equation for the excitation of nerve fits the strength-duration curve for Calliactis but does not approximate closely to that for Cerianthus. Complete curves of the strength-duration relation and the relative refractory period will be published elsewhere.

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  1. 1

    Hill, A. V., Proc. Roy. Soc., B, 119, 305 (1936).

  2. 2

    Pantin, C. F. A., J. Exp. Biol., 12, 119 (1935).

  3. 3

    Torelli, B., Pubbl. Stat. Zool. Nap., 23, 141 (1952).

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  1. Gatty Marine Laboratory, St. Andrews

    • G. A. HORRIDGE


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