Spermatocytes
Explanation of Plate VIII.
Explanation of Plate VIII.
Explanation of Plate VIII.
Fig. 17.Two cells in metaphase—a pole view of one and an oblique view of the other. The accessory chromosome does not show in the former, the cell being such a one as is represented in figures 14 and 15.
Fig. 18.Pole view of another cell, showing but sixteen chromosomes.
Fig. 19.Early anaphase of the first spermatocyte, with the accessory chromosome already at one pole.
Fig. 20.Mid-anaphase, with the giant chromosome still undivided.
Fig. 21.Later anaphase, in which the accessory chromosome is seen at the lower pole. This figure shows, also, the character and extent of the intercellular material.
Fig. 22.Later anaphase. The accessory chromosome at the upper pole. An undivided chromosome lying between the groups of daughter chromosomes.
Fig. 23.About the stage of figure 22, but the lagging chromosome has divided.
Fig. 24.Very late anaphase. Here, again, the lagging chromosome is divided.
Fig. 25.Pole view of first spermatocyte telophase, showing the accessory chromosome at one side of the daughter chromosomes.
Fig. 26.Pole view of a cell in the same stage as that represented in figure 25. Here, however, the accessory chromosome is not present.
Fig. 27.Lateral view of telophase, with the accessory chromosome in the lower daughter-cell.
Fig. 28.Fragment of second spermatocyte, showing the chromosomes in metaphase. The relative sizes of the accessory chromosome and the remaining chromosomes is well shown.
Fig. 29.Metaphase of a second spermatocyte, in which the accessory chromosome is not present.
Fig. 30.Anaphase of second spermatocyte, in which there is no accessory chromosome.
Fig. 31.Anaphase of second spermatocyte, where the accessory chromosome is present—x1andx2.
Fig. 32.Telophase of the same class of second spermatocytes. The accessory chromosome extends out from the mass of chromosomes at each pole—x1andx2.
Fig. 33.Telophase of the class of second spermatocytes from which the accessory chromosome is absent.
Spermatocytes
Explanation of Plate IX.
Explanation of Plate IX.
Explanation of Plate IX.
Fig. 34.Photomicrograph of early spireme stage of first spermatocyte, showing peripheral position of the accessory chromosomex. At the left, secondary spermatogonia, last generation. × 1300.
Fig. 35.A late prophase, showing accessory chromosomex, and spindle remainss(cf.figs. 3 and 4). × 1300.
Fig. 36.Coarse spireme of first spermatocyte. × 1300.
Fig. 37.Prophase, with chromosomes in the form of long segments. Ata, the cell drawn in figure 9. In the cyst at the left are spermatocytes in a later stage, with the chromosomes homogeneous. × 1000.
Fig. 38.Prophase with segments divided longitudinally and across. Atais one shownen face. Accessory chromosome at x. × 1000.
Fig. 39.Metaphase and anaphase of first spermatocyte. The accessory chromosomexat one pole of the spindle. Lagging chromosome atc. × 1300.
Spermatocytes
Explanation of Plate X.
Explanation of Plate X.
Explanation of Plate X.
Fig. 40.Anaphase of first spermatocyte. Accessory chromosomexat one pole. The form of chromosome in the anaphase well shown. The lagging chromosomecseen in two cells. × 1300.
Fig. 41.Anaphase of the first spermatocyte, showing the longitudinally divided condition of the accessory chromosomexin the cell near the center. Compare with the accessory chromosome in the metaphase of second spermatocyte, figure 43. × 1300.
Fig. 42.Second spermatocyte in metaphase. In most of the cells the focus is upon the ends of the chromosomes, but in one a side view is obtainable. Compare with the chromosome of the upper cell in figure 40. No accessory chromosome in most of the cells in focus. × 1300.
Fig. 43.Second spermatocyte metaphase and spermatids. Note the relative sizes of the accessory chromosome and the other chromosomes. In the spermatids the accessory chromosome has taken its place on the periphery of the nucleus in the same way that it does in the prophase of the first spermatocyte. × 1300.
Fig. 44.Anaphase of the second spermatocyte, showing the accessory chromosomexseparated. Other cells in metaphase. × 1300.
Fig. 45.Telophase of the second spermatocyte. Two daughter-cells with persisting spindle between, showing the accessory chromosomexin each. Other nuclei in focus show no accessory chromosomes. × 1300.
Spermatocytes
TRANSCRIBER’S NOTESSilently corrected obvious typographical errors and variations in spelling.Retained archaic, non-standard, and uncertain spellings as printed.
TRANSCRIBER’S NOTES
TRANSCRIBER’S NOTES
TRANSCRIBER’S NOTES
TRANSCRIBER’S NOTES