19091 SCHAFFNER— REDUCTION DIVISION IN AGAVE 207 



ance very much like the figures usually given to represent multipolar 

 spindles. The writer believes that these connecting fibers have 

 caused much trouble in the interpretation of spindle sections. Fig. 

 6j might be taken for a tripolar spindle. The few projecting fibers 

 were probably disturbed in the cutting. Fig. 68 is a spindle broken 

 and distorted by the knife. Fig. 6g is another torn spindle, the fibers 

 at one end being spread out by the knife. Fig. 70 has the fibers of one 

 pole cut diagonally. In fig. 71 one pole is perfect, with a well- 

 developed aster, while the other pole is cut away. In figs. 72, 73 

 both poles have been cut off. Such figures are common, as is neces- 

 sarily the case with cells in which the spindles lie in all directions. 



The division of the bivalent chromosomes— -The chromosomes are 

 ananged symmetrically in the mother star (fig. 61), with the closed 

 end of the loop extending outward, at least in the long chromosomes 

 (k- 61, a, b t c, d, e). The spindle fibers are attached very near or at 

 the free ends. In the following division the general appearance is 



entirely different. The larger chromosomes are V-shaped and are 

 attached to the spindle fibers at the head of the V, the two free ends 

 projecting outward (fig. 62). The individual character of the 

 chromosomes may occasionally be seen from the polar view, even 

 35 late as the mother-star stage (fig. 63) . The chromosomes are 

 P u Ued apart very rapidly and are considerably scattered before they 

 r each their new positions in the daughter stars (figs. 74-77)- In some 

 one can see large nucleoli in the cytoplasm along with micro- 

 nucleoli (ft,. 57 _ 5p , ^ ^ 



1 hc daughter chromosomes are arranged in a loose ring or plate 



cell 



P 



and then begin to contract, until they form a compact dark-staining 

 "!** {figs. 78-82). In the earlier stages of the daughter star, con 

 "ions are again favorable for counting the chromosomes (fig- 79) » 

 an d their smaller size is quite evident when compared with the bivalent 

 chromosomes of the mother star. Delicate radiations are usually 

 *»* in all of these stages (figs. 7 5~77, 81, 82). 



^ter the contraction stage of the incipient daughter nuclei, tne 

 r.° matin begins to expand, the chromosomes putting out pseudo- 

 P°*a-like branches which become more extended until a coarse net 

 formed (fi gs . g^ . but eyen in the oWest daught er nuclei dis- 

 enable before the beginning of the following division, a con- 



e) lllulll 6 



