. The Biological bulletin. Biology; Zoology; Marine biology. 478 JAMES CASE AND M. S. TRINKLE sources were calibrated against a Gamma Instruments standard lamp using a Reeder Thermopile and Keithley millimicrovoltmeter. Nor-epinephrine was injected with a Hamilton microliter syringe. The saline of Brunelli cf al. (1968a) was used for preparing nor-epinephrine solutions and in the saline bridge experiments. Results 1. Inhibition of spontaneous fiasJiing Interruption of spontaneous flashing by electrical stimulation of the eye (Case and Buck, 1963) or by illumination of the eye (Magni, 1967) was
. The Biological bulletin. Biology; Zoology; Marine biology. 478 JAMES CASE AND M. S. TRINKLE sources were calibrated against a Gamma Instruments standard lamp using a Reeder Thermopile and Keithley millimicrovoltmeter. Nor-epinephrine was injected with a Hamilton microliter syringe. The saline of Brunelli cf al. (1968a) was used for preparing nor-epinephrine solutions and in the saline bridge experiments. Results 1. Inhibition of spontaneous fiasJiing Interruption of spontaneous flashing by electrical stimulation of the eye (Case and Buck, 1963) or by illumination of the eye (Magni, 1967) was readily confirmed in Photuris missouriensis. In this species the specificity of the interruption appears to be sufficient to permit use of the term inhibition in regard to the. y I A 1 1 1^+ B Figure 2. Two sequential photic inhibitions showing that a very brief ^-second, 50-lux flash (2B) can be as effective as a much longer, 100-lux illumination. Upper trace, light organ with some registration of stimulating lamp, which is recorded on lower trace. Time mark, 1 second. phenomenon. Certainly, the effect is not simply an alarm reaction since Photuris responds to injury or disturbance with rapid flashing. The latency of inhibition is nearly the same for electrical and photic stimulation of the eye. Our most extensive latency measurements were made with light stimuli from either an incandescent or xenon arc lamp. Light stimuli were delivered at random during episodes of regular spontaneous flashing. Latency was estimated as the time from initiation of illumination to the time of the next succeeding modified flash (usually reduced in magnitude) or completely suppressed flash (time of ex- pected occurrence was estimated from the average interflash interval of the preced- ing series). Results appear in Table I and an example of the records from which the Table was constructed appears as Figure 1. Clearly, illumination at intervals as brief as 160 msec, prior to an expected flash is
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