PLATE 59 



Crepis bursifolia. 



Fig. 16, heterotypic anaphase; fig. 17, homotypic metaphase; fig. 18, homo- 

 typic anaphase; note the short chromosome in all four groups of chromosomes. 



Crepis aspera X bursifolia, Fj. 



Sectioned material. Fixation: Figure 30, Carnoy; all the others Carnoy- 

 Navashin and all stained in gentian violet-iodine-orange G. 



Figs. 19-22. Selected diaphases in which four bivalents occur. Note the con- 

 jugation of the unequal pair and the chiasmas in figures 19-21; in figure 20 it 

 has been necessary to draw one bivalent outside the nucleus. 



Figs. 23-29. Heterotypic metaphases. Figure 23 has 4ii, figures 24-25 3ii + 

 2i, figure 26 has 2ii + 4i; in figure 27 there is In + 6i and in figure 28, finally, 

 all 8 chromosomes are unpaired (non-reduction). In figure 23 probably the left 

 bivalent is the unequal one; in figure 24 the two unpaired chromosomes are the 

 unequal ones, in figure 25 these are conjugated, resembling a pair of X¥ chromo- 

 somes, while two equal chromosomes here are unpaired. In figure 29 (not com- 

 plete) an unequal pair very clearly shows. 



Fig. 30. Heterotypic anaphase giving 4 long chromosomes in one of the 

 daughter nuclei and 3 long and one short in the other. 



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