974 
Davis,—Reduction Divisions of Oenothera . 
PLATE LXIII. 
Figs. 64-79, Oenothera gigas. 
Fig. 64. Early prophase of the heterotypic mitosis. Nineteen chromosomes are shown, some 
of them evidently paired; the remaining nine chromosomes were present in the adjacent section. 
The nuclear membrane has disappeared and fibrillae have entered the nuclear cavity. 
Fig* 65. A multipolar spindle. Some of the chromosomes are still arranged end to end. 
Fig. 66. Metaphase of the heterotypic mitosis. Fourteen chromosomes were present in each 
group at the equatorial plate. Compare with Fig. 27. 
Fig. 67. Anaphase of the heterotypic mitosis. Fourteen chromosomes in each of the two sets 
which pass to the poles of the spindle, some of the chromosomes showing the fission in preparation 
for the homotypic mitosis. Compare with Fig. 28. 
Fig. 68. Anaphase with split chromosomes at the poles of the spindle. 
Fig. 69. An irregularity in the heterotypic mitosis. Two chromosomes have become separated 
from each of the main groups at the poles of the spindle. 
Fig. 70. A condition following such an irregularity in the heterotypic mitosis as that shown in 
Fig. 69. The appearance of the chromatin indicates that such nuclei pass into a resting condition. 
Figs. 71 and 72. Resting nuclei of the interkinesis between the heterotypic and homotypic 
mitoses. The fourteen pairs of chromosomes are shown, mostly in the form of U’s joined in the 
bent middle region. Compare with Fig. 33. 
Fig. 73. Early prophase of the homotypic mitosis; fourteen pairs of chromosomes. The 
nuclear membrane has disappeared. 
Fig. 74. Metaphase of the homotypic mitosis. The chromosomes are now in a much more 
condensed form than during the interkinesis. 
Fig. 75. Early anaphase of the homotypic mitosis. Compare with Fig. 37. 
Fig. 76. Late anaphase of the homotypic mitosis. 
Fig. 77. Telophase of the homotypic mitosis, the fourteen chromosomes beginning to show 
irregularities of form. 
Fig. 78. Pollen mother-cell in telophase of the homotypic mitosis. Compare with Fig. 40. 
Fig. 79. Nucleus of a young pollen-grain, showing the open reticulum. 
