EFFECTS ON NUCLEI AND NUCLEAR DIVISION 233 



a condition frequently observed, where some of the chromosomes ap- 

 pear to have been hindered in their advance to the poles, and project 

 out from the mass of the daughter-nuclei along the spindle, extending 

 almost to the equator. In figure 13 (plate 5) is shown a tend- 

 ency of the spindle to separate into two independent and parallel 

 portions, suggesting that, if the process had continued, two separate 

 nuclei would have formed in each daughter-cell. This figure should 

 be compared with figure i, plate 6. 



Frequently one or more of the chromosomes that failed to become 

 incorporated into the daughter-nuclei would organize smaller, second- 

 ary nuclei, thus giving the cell the appearance of being multi- 

 nucleate. As many as six of these secondary nuclei were observed 

 in some cells, in addition to the main nucleus (plate 6, figures 

 I, 3, and 6). 



One of the most interesting variations observed is illustrated in 

 PLATE 6, figure I. One nucleus had formed in one daughter-cell, 

 and two in the other, all three appearing abnormal ; but, in addition 

 to these, a group of chromosomes that failed to participate in the 

 major mitosis, has organized a secondary nucleus near one wall of 

 the mother-cell, and this nucleus has undergone an independent and 

 tardy karyokinesis, the late telophase of which is shown in the figure. 

 Possibly an early stage of this process is illustrated in figure 17, 

 PLATE 5, and FIGURES 7 and 9, plate 6. 



Such an instance as this is some evidence that a multinucleate 

 cell in material exposed to radium rays, may not always be correctly 

 explained as due to amitosis. This variation also suggests interest- 

 ing possibilities in connection with sectorial variation and bud-sport- 

 ing, and this will be referred to later in Chapter XVIII. 



A number of exposures were made of ovaries of Henierocallis 

 fulva and H. Ititea^ to rays from radium of various activities, but, 

 for some unexplained reason, none of these ovaries, nor indeed of 

 those on neighboring plants, set seed, and, as no other suitable plants 

 were at hand in flower when the radium preparations were available, 

 only negative results can be reported on these experiments. The 

 effect of the rays on vegetable cells, however, as just described, con- 

 firms Koernicke's* results with the pollen-mother-cells and embryo- 

 sac-mother-cells of Lilitim fuartagon, and indicates the ability of the 

 rays profoundly to modify indirect nuclear division. 



