ioio Gates.— Somatic Mitoses in Oenothera. 
Fig. 19. Equatorial plate, showing (exceptionally) sixteen chromosomes with some indications 
of pairing. 
Fig. 20. Equatorial plate, showing (exceptionally) only twelve chromosomes. They clearly 
form six pairs. The two outermost show the beginnings of a precocious split. 
Fig. 21. Equatorial plate showing (exceptionally) eighteen chromosomes. The whole number 
present was twenty or twenty-one. One chromosome shows the beginning of a precocious split. 
See text. 
Fig. 22. Early anaphase, showing the two daughter groups of chromosomes (fifteen each) in 
equatorial view, from different foci of the same cell. 
Fig. 23. Later anaphase, showing the chromosome loops being drawn to the poles. Spindle 
poles now broad, and spindle fibres nearly parallel. 
Fig. 24. Later stage than last. The chromosomes have reached the poles and the thickenings 
of the fibres in the median region of the spindle have already appeared. 
Fig. 25. Same stage as last. First indications of cell- wall. 
Fig. 26. Slightly later stage. The chromosomes have formed a compact group at each pole. 
Fig. 27. Telophase. The membrane has been formed around the daughter nuclei, and the 
chromosomes — now very small — have mostly taken on the shape of dumb-bells owing to a median 
constriction. The full fifteen chromosomes can be counted in the upper nucleus. 
Fig. 28. Same stage as last, showing the fifteen chromosomes, nearly all having a clear median 
constriction. 
Fig. 29. Later telophase than last. The nuclear cavity has increased in size, the chromosomes 
are larger and have mostly lost their constriction. Fifteen chromosomes present. 
Fig. 30. Later telophase, showing both daughter nuclei. The drawing-out and anastomosis of 
the chromosomes has begun. 
Figs. 31-33. Same stage as last. Not all the chromosomes represented. 
Figs. 3 4 a, 34 b. Two telophase nuclei from one cell. The centres of the chromosomes still 
remain condensed. In 34 b the full fifteen chromosomes are shown, several of them still showing the 
median constriction. 
Fig. 35. Later stage than Fig. 34. The reticulum is becoming better developed, but portions 
of the chromosomes still remain in the condensed form. 
Fig. 36. The completely resting condition, like Fig. 1 but smaller. A uniform, slightly 
moniliform reticulum fills the nuclear cavity. 
Fig. 37. An abnormal cell from the nucellus. The spindle is much larger than in an ordinary 
nucellar cell, being nearly as long — though not so broad — as the heterotype spindle (Fig. 38). The 
chromosomes are mostly in close pairs, lying side by side but irregularly oriented on the spindle. 
The members of these pairs are much more closely associated than in normal mitoses (cf. Figs. 
1 7-20), and it seems probable that this will be followed by a reduction of the chromosome pairs. 
In Fig. 37 a several of these chromosomes are drawn separately; a and b are two chromosome pairs, 
c a partly fused pair, d a single chromosome, and the other three represent partly fused pairs. 
Fig. 38. Megaspore mother-cell drawn on same scale, showing heterotype mitosis with fifteen 
chromosomes present. The chromosomes differ sharply in size and shape from those of the 
somatic cells. 
