. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. I**"1. I-H FIGURE 10. Effect of transaction of the ventral nerve cord between the sixth and seventh abdominal segments of a female, Pliotnris sp. Except where noted otherwise the following conditions were maintained. Top trace: up, 21% oxygen; down, .05% oxygen. Middle and bottom traces: light intensity except where otherwise noted, amplification of bottom trace being 500 times middle trace. (A) Normal pseudoflash, both sixth and seventh abdominal segments give a total flash. Spontaneous flashing is seen in this figure,
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. I**"1. I-H FIGURE 10. Effect of transaction of the ventral nerve cord between the sixth and seventh abdominal segments of a female, Pliotnris sp. Except where noted otherwise the following conditions were maintained. Top trace: up, 21% oxygen; down, .05% oxygen. Middle and bottom traces: light intensity except where otherwise noted, amplification of bottom trace being 500 times middle trace. (A) Normal pseudoflash, both sixth and seventh abdominal segments give a total flash. Spontaneous flashing is seen in this figure, as well as in B, during onset of hypoxia. (B) Normal pseudoflash, sixth segment masked. Note the reduction in intensity of the pseudoflash since only the seventh segment is being recorded. (C) Inability to induce pseudoflash in segment 7, 8 minutes after transection, sixth segment masked. Top trace: up, oxygen; down, oxygen. Light leak from sixth segment appears as small flashes on left, bottom trace. (D) Pseudoflash 20 minutes after transection, seventh segment masked, showing response in sixth segment still normal. Amplification of light signal in bottom trace, 1000 times middle trace. (E) Pseudoflash 45 minutes after transection with stimulation, sixth segment masked. Stimulating electrode pair inserted laterally into the seventh segment dorsal to the light organ. Middle trace: stimulus signal. Bottom trace: light intensity with same amplification as before. Stimulation: 15 volts, 20-msec. duration, frequency 20 per second. In some instances, transection of nerves supplying the light organ of abdominal segment 7, at the level of the intersegmental membrane between segments 6 and 7, abolishes spontaneous flashing in the seventh segment and leaves unaffected the light organ of segment 6. Gradual reduction of hypoxic glow and pseudoflash intensity occurs in segment 7 until both are completely abolished after two hours, while the response in segment 6 can be maintain
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
