PLATE 60 



Crcpis aspera X bursifoUa, F,. 



Figures 31-34 from sectioned material, figure 31 from Carnoy fixation, the 

 others from Carnoy-Navashin, all stained in gentian violet-iodine-orange G. Fig- 

 ures 35-41 are from iron-acetocarmine smears, previously fixed in Carnoy and 

 preserved in 70 per cent alcohol. 



Fig. 31. Heterotypic anaphase; one chromosome eliminated, the short chromo- 

 some splitting in the equatorial plane. 



Figs. 32, 33. Homotypic anaphase. Figure 32 has five chromosomes at one 

 pole, two at the opposite pole, and one (the small one?) splitting outside both 

 daughter groups of chromosomes. 



Fig. 34. Homotypic anaphase in one section; the left picture represents the 

 upper cap of the pollen mother cell. The short chromosome is seen in this cap. 



Figs. 35-41. Polyads representing the tetrad stage. Figure 35 apparently 

 will form a diad with two and four nuclei respectively. Figure 36 probably rep- 

 resents a diad, but possibly it might belong to interphase (interkinesis) ; three 

 micronuclei are seen. Figures 37 and 39 are tetrads with .micronuclei. Figure 

 28 is a pentad, figure 40 a tetrad, but one of its cells is very small and one is 

 very large with three micronuclei. Figure 41 is a true triad. 



Crepis taraxacifolia X tectorum, F,. 



Smear preparations fixed previously in Carnoy and stained in iron-acetocar- 

 mine. 



Figs. 42-45. Heterotypic metaphases. In figure 42, 4ii; in figure 43, 3,i -+- 

 2i. Figures 44 and 45 have 2i, + 4, each, but in figure 44 the bivalents form 

 a cross and a rod, respectively, while in figure 45 they form two crosses. 



[430] 



