PLATE VI 



Meiosis in Interchange Hybrids 



Figs, i and 2. — First metaphase in Campanula persicifolia {2n = 16). 

 Fig. I. Ring of four and six pairs. Fig. 2. Ring of six and five 

 pairs. (Gairdner and D., 1931.) 



Figs. 3 and 4. — Metaphase in Rhceo discolor, rings of twelve chromo- 

 somes, showing non-disjunction in side and polar view. (La Cour : 

 medium Flemming — gentian-violet smear, x 2500.) 



Fig. 5. — Normally segregating ring of chromosomes at beginning of 

 first anaphase in (Enothera muricaia, five chromosomes shown. 



Figs. 6-8. — The exceptional occurrence of interstitial chiasmata in 

 (Enothera biennis at metaphase and anaphase. 



Fig. 7. The critical " figure-of-eight " configuration. Fig. 8. 

 The interstitial chiasma leads to lagging at anaphase [v. Chap. 

 IX). (From D., 1931 d.) x 6000. 



Figs. 9-11. — The same in Pisum sativum with a ring of six. 

 Note the critical chiasma in Fig. 10. (C/. Text-Figure. From E. R. 

 Sansome, 1932.) x ca. 3000. 



