. Biological lectures delivered at the Marine Biological Laboratory of Wood's Holl [sic]. Biology. Fig. 19. Fig. 20. Fig. 19. —Podarke. Cross formed by spiral divisions (after Treadwell). Fig. 20.— Chcetoptenis. Cross does not appear because of extreme spiral character of divisions which commonly give rise to it (after Mead). wish to mention here some of my own observations on Arcfii- cola without reference to other forms, for, where special at- tention has not been paid to this point, figures and general statements are usually too indefinite to serve in this connec- tion. The cross in Arenico
. Biological lectures delivered at the Marine Biological Laboratory of Wood's Holl [sic]. Biology. Fig. 19. Fig. 20. Fig. 19. —Podarke. Cross formed by spiral divisions (after Treadwell). Fig. 20.— Chcetoptenis. Cross does not appear because of extreme spiral character of divisions which commonly give rise to it (after Mead). wish to mention here some of my own observations on Arcfii- cola without reference to other forms, for, where special at- tention has not been paid to this point, figures and general statements are usually too indefinite to serve in this connec- tion. The cross in Arenicola is formed by radially symmetrical divisions (Fig. 7). In the division following this the four cells terminating the arms of the cross often show traces of spiral divisions. This is especially noticeable in the ventral arms of the cross (Fig. 8, i^a:"'", k^-""'), which often curve at the tip toward the right side of the Both the spindle and the position of the cells after division indicate in many cases the spiral nature of the cleavage. The direction is laeotropic, as it. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ). Boston, Ginn & Co
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectbiology
