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Journal of Experimental Biology 46,571-583 (1967)
Published by Company of Biologists 1967

Slow Activity in the Nervous System of the Earthworm, Lumbricus Terrestris

M. B. V. ROBERTS ¹

¹ Biology Department, Marlborough College, Wiltshire

1. Three thresholds are demonstrated in the first segmental nerve and two (sometimes three) in the second and third segmental nerves together.

2. Slow potentials recorded from the ventral nerve cord consist of several peaks. The first peak is composed of three spikes which make their appearance at different thresholds. Transmission of at least some of the slow potentials is decremental.

3. Transmission speeds in the nerve cord and segmental nerves range from 0.4 to 0.6 m./sec.

4. Action potentials in the longitudinal muscle are recorded in response to slow potentials in the nerve cord.

5. Two slow reflexes, one involving elongation, the other longitudinal contraction, are described. The latter has the lower threshold with peripheral stimulation.

6. Slow activity in the nervous system is discussed in relation to reflex activity of the earthworm and the neurone anatomy of the nerve cord and segmental nerves.