470 BOTANICAL GAZETTE [December 



chromosomes, each derived from one of the loops (fig. 170). These 



% 



24 bivalent chromosomes gather near the center of the nucleus 

 (fig. 171), and then are arranged at the equatorial plate (fig. 172), 

 when the number is clearly counted in the polar view (fig. 173). 

 Then each of the chromosomes splits longitudinally (fig. 174) and 

 half of each proceeds to each pole of the spindle and there again the 

 polar view of the anaphase clearly shows 24 chromosomes 

 175). The chromosomes grouped at the poles now become closely 

 applied to one another (figs. 176, 177) and finally there are organized 

 two daughter nuclei (fig. 178). Up to this phase a kinoplasmic 



or 



mass persists, either surrounding the nucleus or near the pole of 

 the spindle, but centrosome-like structures are recognizable only 

 at metaphase. 



The two newly formed daughter nuclei now increase in size. 

 Their relative position within the cell is variable; sometimes they 

 are wide apart (fig. 180), and often they lie for a while in close 

 contact (fig. 182). The centrosome-like structure with radiations 

 is present, associated with the two resting nuclei (fig. 180). These 

 two nuclei may divide simultaneously or in succession (figs. 183- 

 185). The number of chromosomes present during this division 

 is also 24, and with this reduced number the nuclei pass into telo- 

 phase (figs. 186-188). The third division follows the second after 

 a short rest, 24 chromosomes being present at metaphase (fig. 189)- 

 As a result of the third division there are produced eight nuclei 

 within the mother cell (fig. 190). 



It is interesting to note the relative position of the axes of the 

 mitoses that occurred within the mother cell. Only a few of the 

 cases are represented in fig. 13. As the figures clearly show, the 

 axis of the first mitotic figure is either in the direction of the long 

 axis of the mother cell, or slightly oblique to the axis; in some cases 

 the axis is still more oblique, until finally the axis of the figure is 

 perpendicular to the long axis of the cell. In the second mitosis, 

 considering the cases where the two mitotic figures occur at the same 

 time, the relative position, as shown in figures, shows all possible 

 directions of the axes. The same is true of the third nuclear divi- 

 sion. All of these zoospore mother cells show no polarity in regard 

 to the axis of the mitotic figures. 



