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Journal of Experimental Biology 30,170-177 (1953)
Published by Company of Biologists 1953

On Certain Properties of the Flight Muscles of the Orthoptera

D. W. EWER ¹ and S. H. RIPLEY ¹

¹ Department of Zoology, University of Natal, Pietermaritzburg

1. Kymographic recordings have been made of the movements of the tergosternal muscles of Locusta migratoria when the motor nerve is stimulated at different frequencies and intensities.

2. At low intensities of stimulation the muscles respond with discrete twitches regardless of the frequency of stimulation. At high intensities and frequencies the muscles contract with a smooth tetanus. These findings confirm the earlier observations of Voskresenskaya (1947).

3. Electrical recordings from the tergo-sternal (muscle 113), dorsal longitudinal (muscle 112) and depressor extensor (muscle 129) of the locust wing, as well as from the muscle corresponding to the latter in the cockroach, show that the discrete twitches obtained at high-frequency and low-intensity stimulation arise from a long period of subnormal excitability of the nerve and are not to be attributed to any inherent rhythm of contraction in the muscles.