Addendum

Wakabayashi & Hagiwara (1953) and Hagiwara & Watanabe (1954) have published a study of the physiology of the cicada tymbal muscle in Japanese species. They report that in Graptopsaltria nigrofuscata, Oncotympana maculati-collis, Tanna japonensis and Meimuna opalifera twitches accompany each impulse in the motor-nerve fibre, whose natural discharge during ‘shrilling ‘consists of a series of bursts of impulses of about 100/sec. (29o C.). Intracellular electrodes record the normal type of resting and action potential, with little overshoot except in Platypleura kaempferi. In a more recent paper (Hagiwara, Uchiyama & Watanabe, unpublished; I am grateful to Dr Hagiwara for showing me the manuscript) P. kaempferi is shown to have a myogenic rhythm in the tymbal muscle, and results are described which confirm many of the findings reported here and in Pringle (1954 a); on the other hand, Meimuna opalifera shows always a 1:1 relationship between nerve impulses and sound...