. The Biological bulletin. Biology; Zoology; Marine biology. 524 M. YOSHIDA AND H. OHTSUKI Shadows cast on eyeless animals in the same way affected the locomotory direction only in few cases, where they moved mostly sideways (Fig. 6D upper row). The return action may have come into play also in this case, for per- centages of the arm I taking the lead were much higher at 35 and 55 seconds (middle and lower rows) than at 15 seconds after shading. These results strongly suggest that the ocelli do function as photoreceptive sites. (c) Effects of transection of the circumoral nerve ring. The oral
. The Biological bulletin. Biology; Zoology; Marine biology. 524 M. YOSHIDA AND H. OHTSUKI Shadows cast on eyeless animals in the same way affected the locomotory direction only in few cases, where they moved mostly sideways (Fig. 6D upper row). The return action may have come into play also in this case, for per- centages of the arm I taking the lead were much higher at 35 and 55 seconds (middle and lower rows) than at 15 seconds after shading. These results strongly suggest that the ocelli do function as photoreceptive sites. (c) Effects of transection of the circumoral nerve ring. The oral nerve ring may be considered to be a possible route through which the information concerning environmental changes could pass in order to induce coordinated movements in 15 sec 35 sec 55 sec. A B C D Figure 6. Comparison of the effect of shading three arms of moving specimens between intact and eyeless animals. The way of presentation is the same as in Figure 4. A and C: intact animals. B and D: eyeless animals. Number of experiments: A, 49; B, 29; C, 45; D, 29. tube feet. This was studied by transecting the oral nerve ring at an interradius. Experiments were made by casting a shadow (1) on arm I (the same as Fig. 4A) with a cut between I and II, II and III or III and IV, (2) on arm II (the same as Fig. 4B) with a cut between II and III, III and IV or IV and V, (3) on arms I and II (the same as Fig. 5A) with a cut between I and II, II and III, III and IV, IV and V or V and I, (4) on arms I, IV and V (the same as Fig. 6C) with a cut between II and III, and (5) on arms I, II and V (the same as Fig. 6A) with a cut between I and II, III and IV or IV and V. The number of experiments in each case was 23-42. To avoid undue complica- tion, only the results obtained with the last combination are presented in Figure 7. I I. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illust
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