BOT.— Vol. I.] WILLIAMS— PASSIFLORA CCERULEA. 193 



the reticulum. The entire network stains uniformly (fig. 

 12), although the fibers inside of the granular zone differ 

 in appearance from those outside of it. They are delicate 

 and clear cut, while those outside are much thicker, more 

 granular and less fibrous in structure. This difference 

 between the parts of the reticulum inside and outside of the 

 granular zone is more marked in the later stages. 



The first indication of the formation of the spindle poles 

 is a decided change in the portion of the reticulum sur- 

 rounded by the granular zone. At various points this part 

 of the reticulum is drawn out into cones, which become the 

 poles of the multipolar spindle (fig. 13). Each cone is 

 composed of a reticulum whose meshes become stretched in 

 the direction of the long axis of the cone and finally become 

 fibers, many of which end free. A little later all traces 

 of a reticulum inside of the granular zone disappear. The 

 whole space limited by the zone is filled with free fibers 

 which cross each other in all directions. Many of them 

 converge at their extremities to form the poles of the 

 multipolar spindle (fig. 14). At first the poles point in all 

 directions, but soon they show a tendency to assemble in 

 two groups (fig. 15), which are probably destined to form 

 the poles of the bipolar spindle. The chromosomes assume 

 a more central position than they have had heretofore and 

 are more crowded together. The poles of these two groups 

 gradually fuse (figs. 16 and 17) until finally a sharp-pointed, 

 bipolar spindle results (fig. 18). In the equatorial plate 

 stage, the spindle is usually long, very narrow, sharply 

 pointed, and without mantle-fibers. Sometimes, however, 

 there are long mantle-fibers which extend from the poles 

 and pass obliquely to the cell-wall, the fibers from each 

 pole crossing those from the opposite pole in their course. 

 Often the poles extend to the cell-wall. In the meta- 

 phase, also, the poles may extend to the cell-wall; man- 

 tle-fibers are more often seen in this stage than in the 

 equatorial plate stage. At this time, too, the spindle is 

 usually broader than in earlier stages and its outline is 

 more nearly elliptical. Often, in this stage, the groups 



