. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 360 C. D. DARLINGTON pends on size differences. The loops first meet, revealing the number and position of the chiasmata, in the shorter pairs. As the loops open the doubleness of the chromosomes becomes detectable (Fig. 2). The chromatids can then be followed separately through the chiasmata and sometimes throughout their length. Later they swell considerably and cease to be separately identifiable, except at the chiasmata (Fig. 9). This swelling is seen in many animals (perhaps Pristiurus may be re- garded as the extreme t

- Image ID: RHP5J0
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 360 C. D. DARLINGTON pends on size differences. The loops first meet, revealing the number and position of the chiasmata, in the shorter pairs. As the loops open the doubleness of the chromosomes becomes detectable (Fig. 2). The chromatids can then be followed separately through the chiasmata and sometimes throughout their length. Later they swell considerably and cease to be separately identifiable, except at the chiasmata (Fig. 9). This swelling is seen in many animals (perhaps Pristiurus may be re- garded as the extreme t
Library Book Collection / Alamy Stock Photo
Image ID: RHP5J0
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 360 C. D. DARLINGTON pends on size differences. The loops first meet, revealing the number and position of the chiasmata, in the shorter pairs. As the loops open the doubleness of the chromosomes becomes detectable (Fig. 2). The chromatids can then be followed separately through the chiasmata and sometimes throughout their length. Later they swell considerably and cease to be separately identifiable, except at the chiasmata (Fig. 9). This swelling is seen in many animals (perhaps Pristiurus may be re- garded as the extreme type) and also in a gymnosperm, Taxus baccata. 2/0 4/( 3/° '/° '/° y° '/• '/' 3/0 3/i 3/0 2/ 2/ l/o //. I/, 8 ft £*f in* 3/, 3/, 4/, 2/, 2/. I/. I/, I/, X 4/2 3/i 2A l/o l/o I/, l/o I/, X FIGS. 9 and 10. Diakinesis. FIG. 11. Pro-metaphase. FIG. 12. Metaphase, X chromosome lying to one side of the spindle. Note: the three long pairs of chromosomes have median spindle attachments, the rest terminal. (Dark, unpublished). It is characteristically different from the be- haviour in the angiosperms where the more swollen condition prevails throughout the post-pachytene stages and seems to prevent the chroma- tids being so clearly distinguished at diplotene as in some Orthoptera. The differences between angiosperm and orthopteran may, of course, be artefacts but it is impossible to say which is normal and which the artefact. Many would infer that the clearer observation is more true- to-life but such a conclusion does not necessarily follow. The increase in size has a curious effect. Owing to the differential but somewhat. 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 work.. Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Fran

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