LIST OF ILLUSTRATIONS 



FIG. P^GE 



1. Inheritance of tall versus short peas 2 



2. Hybrid pea back-crossed to recessive parent 3 



3. Inheritance of brown versus blue eyes 4 



4. Back-cross of hybrid to recessive blue-eyed individual . . 5 



5. Inheritance of flower color of four-o'clock (Mirabilis) . . 6 



6. Distribution of genes in cross shown in figure 5 . . . . 7 



7. Inheritance of yellow round and green wrinkled peas . . 8 



8. Distribution of genes for three pairs of characters ... 9 



9. Inheritance of two linked characters in sweet peas ... 11 



10. Inheritance of four linked characters in Drosophila ... 13 



11. Inheritance of two sex -linked characters in Drosophila . . 15 



12. Inheritance of the same characters as in figure 11 in recipro- 

 cal combination 16 



13. Inheritance of white eyes and miniature wings of Droso- 

 phila (back-cross) 18 



14. Inheritance of white eyes and forked bristles of Drosophila 19 



15. The location of nine sex-linked recessive genes .... 21 



16. Crossing-over between garnet and vermilion in the series of 

 genes shown in figure 15 21 



17. Crossing-over between echinus and cross-veinless in the series 



of genes shown in figure 15 21 



18. Double crossing-over 21 



19. Chart of the linked genes of Drosophila 23 



20. The order of the genes, yellow, white, bifid, of Drosophila . 24 



21. Maturation of sperm-cell 33 



22. Maturation of the egg 34 



23. Independent assortment of X and a pair of autosomes . . 35 



24. Haploid chromosome groups of edible pea, sAveet pea, and 

 Indian corn 37 



25. Nuclei of daughter cells of Ascaris 39 



26. Conjugation of chromosomes of Batrachoseps 41 



27. Twisted chromosomes of Batrachoseps 42 



28. Conjugation of chromosomes of a planarian, Dendrocoelum 43 



29. Normal and haplo-IV female of Drosophila 47 



