. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 336 C. W. MRTZ. TEXT FIGS. 1-6. Scliematic representation of the movements of the chromo- somes in the monoccntric first spermatocyte division in Sciara coprophila Lint. I >iagram 1. Prophase just before dissolution of the nuclear membrane. The chromosomes are scattered, apparently at random, about the periphery of the nucleus. Diagram 1. IVginning of migration of the chromosomes—six toward the pole and four directly away from it. Diagram 3. Slightly later stage, after the six chromosomes have reached the pole and the oth
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 336 C. W. MRTZ. TEXT FIGS. 1-6. Scliematic representation of the movements of the chromo- somes in the monoccntric first spermatocyte division in Sciara coprophila Lint. I >iagram 1. Prophase just before dissolution of the nuclear membrane. The chromosomes are scattered, apparently at random, about the periphery of the nucleus. Diagram 1. IVginning of migration of the chromosomes—six toward the pole and four directly away from it. Diagram 3. Slightly later stage, after the six chromosomes have reached the pole and the other four have progressed to the periphery of the cell. The two median "retreating" chromosomes are presumed to be at high and low levels, re- spectively, and at the periphery. I liagrams 4-6. Successively later stages showing the migration of the chromo- somes .doiig the periphery of the cell away from the pole, and the beginning of the extrusion process at the point farthest trom the pole. Actually the paths of the retreating chromosomes are only rarely equidistant from une another as shown in these diagrams (see text), and the chromosomes which pass to the pole do not ordinarily retain their polar orientation later than the shown in Diagram 3. The t\\o "limited" chromosomes are represented in black. These regularly pass to the pole and are retained. Among the other chromosomes precise segrega- tion of homoloL'- i- effected. The hook at the proximal end of the retreating chromosome at the right, due to sub-terminal fiber attachment, is presumably char- tii of its homolog also, but is not evident in the latter, probably because of 1, of stretching. As will be seen from the camera drawings (Plate I), the retn < hromosomes are comparatively more elongate than the diagrams incli- «at< - ilsi I igs. 14-18 in Met/. Moses, and Hoppe. loc. cit.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for r
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
