. The Biological bulletin. Biology; Zoology; Marine biology. LIGHT-INHIBITION OF FIREFLY FLASHING 479 possible to attain inhibition with a lead time of 120 msec. Lead times less than 80 msec, do not inhibit the immediately subsequent flash while they do inhibit the next and following flashes. These observations are not unexpected since Case and Buck (1963 ) have shown the minimum latency for excitation of luminescence by brain stimulation in Photuris to be 120-150 msec. 2. Effects of light intensity and duration on inhibition of spontaneous flashes These effects are most puzzling since there a
. The Biological bulletin. Biology; Zoology; Marine biology. LIGHT-INHIBITION OF FIREFLY FLASHING 479 possible to attain inhibition with a lead time of 120 msec. Lead times less than 80 msec, do not inhibit the immediately subsequent flash while they do inhibit the next and following flashes. These observations are not unexpected since Case and Buck (1963 ) have shown the minimum latency for excitation of luminescence by brain stimulation in Photuris to be 120-150 msec. 2. Effects of light intensity and duration on inhibition of spontaneous flashes These effects are most puzzling since there appears to be a triggering effect of light superimposed upon a graded response. Triggering is illustrated in Fig- ure 2 where an extremely brief illumination of not more than ith second with maximum intensity of 50 lux resulted in as much inhibition as continuous illumina- tion of 100 lux for six seconds. Light-dark transitions appear often to be more significant than the total illumination delivered because some Photuris can be maintained in the inhibited state for a longer period by a train of approximately. r(r^^^fc((^^ v^^cca^ Figure 3. Electrical stimulation with paired electrodes in anterior light organ. Flashes recorded as downward deflection of upper trace. Stimulus (5 msec, 5 volts, 1 per second) artifacts and light (1000 lux) on lower trace. Right hand record indicates excitation-flash latency of 136 msec. Time mark at lower right applies to both records: 5 seconds, left; 200 msec, right. one second on, one second off illuminations than by continuous illumination. Almost invariably, during all except the most intense illuminations, flashing is reestablished. Typically (Fig. lb) these escapes are of lower than normal intensity and at a slower frequency than prior to illumination. (The kinetics of the flashes are normal.) There is a marked tendency, however, for flashes sub- sequent to the first several escapes to occur at the same frequency as prior to illumination and
Size: 2600px × 961px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectb, booksubjectzoology
