. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. II I 100- 80- 60 40 20 c. 01234567 DAYS 1 2345 DAYS 12 24 36 48 60 HOURS FIGURE 4. Recruitment of contralateral pathways. Each graph represents the performance of a single individual animal. In these experiments the cut was not allowed to heal. Each straight arrow represents the time when the cut was reopened. Closed circles are from the experimental side of the worm and the open circles are from the control side, (a) The most common pattern obtained. Here the animal does not achieve 100% turning during the length of the
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. II I 100- 80- 60 40 20 c. 01234567 DAYS 1 2345 DAYS 12 24 36 48 60 HOURS FIGURE 4. Recruitment of contralateral pathways. Each graph represents the performance of a single individual animal. In these experiments the cut was not allowed to heal. Each straight arrow represents the time when the cut was reopened. Closed circles are from the experimental side of the worm and the open circles are from the control side, (a) The most common pattern obtained. Here the animal does not achieve 100% turning during the length of the experiment, (b) A gradual improvement of performance was seen in a number of worms, (c) Abrupt acquisition of normal behavior was only seen in one preparation. The dashed portion of the line represents time during which the animal was not responsive. turning approximately 48 hr after the original cut had been made. Characteristi- cally these flatworms only respond with ipsilateral turns part of the time. Where acquisition of 100% turning occurs there is a gradual buildup of the effect so that it may take four or five days before this percentage is reached (Fig. 4b). In one unusual case (Fig. 4c), the animal turned 100% of the time as soon as it had re- covered the behavior. Anatomical considerations A series of worms were examined, histologically, to see if severed nerves had rejoined. Animals were cut on one side and as soon as ipsilateral turning in re- sponse to food was reestablished the animals \vere fixed and sectioned. Examina- tion of healed cuts at the light-microscope level clearly reveal nerve trunks which course across the scarred zone (Fig. 5a). Although the severed nerves realign themselves, the contents, especially of the larger trunks, tend to take on a 'bubbly' appearance (Fig. 5b). Samuel's silver stain (1953) tends to stain the outer edge of nerve axons in flatworms, and the vacuolated appearance of the trunks in the region of the scar may represent swollen
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
