460 BOTANICAL GAZETTE [june 



that the collection 'at first sight appears as a homogeneous mass 

 and a part of the chromosome (fig. 34). These wefts retain their 

 individuality for their full length and many times terminate in 

 a very blunt pole (fig. 34). 



During metakinesis, that is, just at the time when the paired 

 segments separate, the dissociation of the two approximated halves, 

 which originated in the resting stage (figs. 1-11), is finally com- 

 pleted (fig. 35), showing that the splitting or vacuolization of the 

 somatic chromosomes in early prophase was in preparation for the 

 homotypic division. There are now 16 chromosomes, for each half 

 becomes entirely separated from its partner and does not again 

 approximate (figs. 36-39). As the 16 members approach the poles, 

 they shorten considerably, and as they crowd together an end to 

 end formation results, thus forming an irregular spirem 16 chro- 

 mosomes in length (figs. 37, 38). The crowding together continues 

 until the entire chromatin mass is so closely associated that it is 

 very difficult to distinguish the individual members; although, 

 after the new nuclear membrane is formed, the looping spirem is 

 again easily recognizable (fig. 39). 



HOMOTYPIC MITOSIS 



After the new membrane has been formed and the chromatin 

 mass loosened up (fig. 39), anastomoses between portions of the 

 looping spirem are everywhere evident. A coarse reticulum is 

 formed as a result of the continual growth of the nucleus and the 

 chromatin (fig. 40) ; but a resting stage is never reached. The 

 spirem, which consists of 16 segments arranged end to end, will 

 come directly from this reticulum (figs. 41, 42). This continuous 

 spirem is quite regular in outline at first (fig. 41), but as the time 

 for segmentation and formation of the multipolar complex 

 approaches, the thread is more irregular and the outlines of the 

 segments evident (figs. 42, 43); although it is not until the bipolar 

 spindle is visible that the spirem separates into the 16 chromosomes 

 (fig. 44). Simultaneous with this separation there is a pairing; 

 so that 8 pairs of chromosomes come to he upon the spindle fibers 

 (figs. 44, 45). The paired chromosomes do not take the charac- 

 teristic forms of the heterotypic mitosis, for at this time, although 



