LIST OF FIGURES. 



Page 



1. Line 695. Reproductive vigor 42 



A. Average number in first brood 42 



B. Average age of mother at production of first brood 42 



C. Reproductive indices, actual values 42 



2. Line 695 43 



A. Relative rates of descent of the two strains 43 



B. Reproductive indices, superiority 43 



C. Reaction-time curves 43 



3. Line 689 48 



A. Reproductive indices, actual values 48 



B. Reproductive indices, superiority 48 



C. Reaction-time curves 48 



4. Line 691. Reaction-time curves 51 



5. Line 711. Reaction-time curves 53 



6. Line 713. Reaction-time curves 55 



7. Line 714 58 



A. Reproductive indices, actual values 58 



B. Reproductive indices, superiority 58 



C. Reaction-time curves 58 



8. Line 719 64 



A. Reproductive indices, actual values 64 



B. Reproductive indices, superiority 64 



C. Reaction-time curves 64 



9. Line 751. Reaction-time curves 67 



10. Reaction-time curves for lines of Daphnia longispina and composite curves for 



all D. pulex lines 69 



A. Line 762. Reaction-time curves 69 



B. Line 766. Reaction-time curves 69 



C. Line 768. Reaction-time curves 69 



D. Composite curves for all D. pulex lines with curves for Line 751 super- 



imposed 69 



11. Line 794 



A. Reproductive indices, actual values 



B. Reproductive indices, superiority 77 



C. Reaction-time curves 77 



12. Line 795 79 



A. Reproductive indices, actual values 79 



B. Reproductive indices, superiority 79 



C. Reaction-time curves 79 



13. Line 796 82 



A. Reproductive indices, actual values 82 



B. Reproductive indices, superiority 



C. Reaction-time curves 82 



14. Line 740 87 



A. Reproductive indices, actual values 



B. Reproductive indices, superiority 87 



15. Line 740. Reaction-time curves with reaction-time curves for Line 757 super- 



imposed 



16. Line 757. Relative rates of descent of the two strains 97 



17. Line 757. Reproductive vigor 101 



A. Average number in first brood 101 



B. Average age of mother at production of first brood 101 



C. Reproductive indices, actual values 101 



18. Line 757 102 



A. Reproductive indices, superiority 102 



B. Reaction-time curves, with composite curves for all other Simocephalus 



exspinosus lines superimposed 102 



19. Line 757. Reaction-time curves by six-month periods with similar curves for 



Line 740 superimposed 103 



