LIST OF ILLUSTRATIONS 



PLATE FACING PAGE 



1. Mitosis and Meiosis 34 



2. Trisomies of Datura 84 



3. Salivary and Lampbnish Chromosomes 100 



4. Dosage in Datura 172 



5. Chromosome spirals 365 



FIG. PAGE 



1. Tall and short peas 31 



2. Independent assortment 32 



3. Meiosis 36 



4. Triaster and tetraster eggs 39 



5. Vesicular nuclei 40 



6. Nucleoli and chromocentres 41 



7. Constancy of chromosome shape 41 



8. Persistence of chromosomes through interphase 42 



9. Chromosome structure 43 



10. Persistence of spiral structure 43 



11. Zygotene pairing 45 



12. Mendelizing chromosomes 46 



13. Random assortment of chromosomes 47 



14. Linkage 47 



15. Theories of linkage 48 



16. Chromosomes and linkage groups 49 



17. Recombination and chromosome breakage 50 



18. Life cycles 53 



19. Germination of a spore tetrad 54 



20. Pollen lethals in stocks 56 



21. Formation of endosperm 57 

 23. Parthenogenesis 59 

 23. Segregation in diploid parthenogenesis 60 



