iooo Gates . — Somatic Mitoses in Oenothera. 
Critical examination of these figures will show clear evidence of pairing 
between the chromosomes on the equatorial plate. The paired arrange- 
ment first begins to be seen in the late prophase (Fig. n) at the time of the 
precocious chromosome split. The pairing naturally becomes much more 
evident to an observer when the chromosomes arrange themselves in one 
plane on the equatorial plate. Figs. 17 , 18, and 20 show indisputable 
evidences of it. Nearly all the chromosomes in these figures are clearly 
arranged in pairs. It is often impossible, however, to determine any definite 
pairing at all. In Figs. 17 and 18 the chromosome number is odd, from 
which it follows of necessity that one chromosome is unpaired. In Fig. 18 
any observer would scarcely hesitate to decide that all the chromosomes 
are in pairs except the one marked a , while in Fig. 17 there are several 
equally clear pairs, and the chromosome marked a is probably the odd one. 
The twelve chromosomes in Fig. 20 are all evidently arranged in pairs. 
Anaphase and Telophase. 
The anaphases of mitosis are represented by Figs. 22-5. Figs. 22 a 
and 22 b are polar views of the two chromosome groups of the early anaphase 
from the same cell, just after the daughter chromosomes have separated. 
Each group contains 1 5 chromosomes, and the great apparent variation 
in size and shape of the chromosomes is a result of the varying positions 
they occupy in their movement towards the poles. Fig. 23 is a side view 
of a later stage of anaphase, in which the chromosomes, in the form of rods 
or loops, are just reaching the poles. The poles of the spindle have lost 
their sharp-pointed character, and have become broad with the fibres of the 
spindle nearly parallel throughout. 
In Fig. 24 a more compact group of the daughter chromosomes is being 
formed, the spindle is somewhat shortened and broadened, and the first 
indication of a cell-wall has appeared in the median plane of the spindle. 
In Fig. 25 are found the first indications of coalescence between parts of 
chromosomes which are in contact. The first thickening of the spindle 
fibres in the median region gives a shadowy appearance to this part of the 
spindle. In Fig. 2 6 the process of condensation of the chromosome group 
has proceeded farther, until a compact and apparently almost solid mass of 
chromatin is formed at each pole. The thickenings on the spindle fibres in 
the median plane are more definite and sharply localized than in the previous 
figure. The nuclear membrane has not yet begun to appear. 
In the telophase stages the chromosomes frequently change their shape 
in an important manner. The origin of the nuclear membrane has not been 
studied, but it doubtless agrees with the method already known for the 
nuclei of the pollen mother-cells of Oenothera and many earlier-described 
forms. Fig. 27 represents an early stage in the reconstruction of the two 
daughter nuclei. One of these nuclei shows clearly 15 chromosomes, 
