Electrical responses were recorded intracellularly from the compound eyes of a fly (Lucilia) and of several dragonflies (Copera, Agriocnemis, and Lestes). An ommatidium of the dragonflies is made up of four retinula cells and a rhabdom composed of three rhabdomeres while the Lucilia has an ommatidium of seven independent retinula cells and rhabdomeres. The intracellular responses presumably recorded from the retinula cell had the same wave form in the two groups of insects: The responses were composed of two components or phases, a transient spike-like potential and a slow one maintained during illumination. The membrane potential, in the range of -25 to -70 mv., was influenced by the level of adaptation, and it was transiently depolarized to zero by high levels of illumination.

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