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1899 ] STUDIES ON REDUCTION IN PLANTS 25 
Fic. 14. Spindle with chromosomes approaching the nuclear plate. The poles of 
the pes show Sasa! lines of protoplasm indicating centers of force 
mosomes in the nuclear plate stage, but they are in this wigs 
tion so va ie fase it is impossible to see the way in which division takes plac : 
Fics. 16, 17. Chromosomes beginning to separate at the nuclear hae rings, 
paired rods, and tetrads can be seen. The rings and paired rods are lying with the 
long axis parallel with the axis of the spindle, pena aes division has taken place 
in some and is taking place in others, so that the halves of rings form crescent- 
shaped rods, the tetrads are indicated by oe staining portions of the rods or 
ings. 
Fics. 18, 19. A little later condition of the same (metaphase) stage; longitudinal 
division has taken place so that nearly all the rods or halves of the rings have sep- 
arated, and by the pulling of the spindle threads the tetrads are being drawn apart 
pert to the axis of the chromosome, to bring about the reducing division. 
. Polar view of the metaphase, showing that the chromosomes are 
snciines: al ‘aiciah the nuclear plate. Sixteen groups can be counted, bearing in 
mind that a pair of rods, or a tetrad, makes a group. Some of the sivonsiciaes are 
turned somewhat igi especially in fg. 20, which was an ee view of the 
plate, and in some cases the paired rods are seen only from the 
Fic, 22. The bees have nearly separated by transverse div is 
Fics. 23, 24. Tetrads, about 32 on each side, sEyrenenrer 7 ole during the 
anaphase of the first mitosi 
PLATES III-VI, Trillium grandifiorum, 
—_ 
Fic. 1. Portion of the spirem with partial longitudinal division, and a few chro- 
mosomes. 
2, 3, 4, 5. i. stage in the formation of the chromosomes just after the 
ee of the spirem, showing, in some, openings along the middle line, in 
others the ends a. saan the line of cngiteaiant division. Pairs of deeply 
Staining chromatin masses are evident in some of the chromosomes, frequently four 
ee or Meee masses in a single chromosom 
6, 7, 8,9, 10. The nuclear Sean has disappeared, and the chromo- 
Somes are being drawn up to the nuclear plate. 
Fics. 11-17. Various figures showing the metaphase stage, the orientation of the 
chromosomes in the nuclear plate ; in some, as in fg. 77 and 77, the four paired 
masses of denser chromatin are well seen; in fg. 77 the pull of the spindle ge is 
drawing out the middle portion on either side of the broad chromosome, the firs 
Step in the separation of the longit itiaatly divided seginent. 
Fics. 18, 19. Two different stages in the separation of the chromosomes in the V 
form as they are pulled toward the poles 
Fic. 20. Cell plate formed alter first mitosis, and U or horseshoe-shaped chromo- 
Somes lying in position as they approached the poles. 
Fics. 21, 22. Oblique view of two poles, to show the position of the chromo- 
Somes as they come to the poles; in fig. 27 t e group has already elongated some- 
what in the direction of the axis of the spindle for the second mitosis. 
